/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software  Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2006 Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Ben Batt <benbatt@gmail.com>
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 * Implementation of CustomData.
 *
 * BKE_customdata.h contains the function prototypes for this file.
 *
 */

/** \file blender/blenkernel/intern/customdata.c
 *  \ingroup bke
 */
 

#include <math.h>
#include <string.h>
#include <assert.h>

#include "MEM_guardedalloc.h"

#include "DNA_meshdata_types.h"
#include "DNA_ID.h"

#include "BLI_utildefines.h"
#include "BLI_string.h"
#include "BLI_path_util.h"
#include "BLI_math.h"
#include "BLI_math_color_blend.h"
#include "BLI_mempool.h"

#include "BLT_translation.h"

#include "BKE_customdata.h"
#include "BKE_customdata_file.h"
#include "BKE_global.h"
#include "BKE_main.h"
#include "BKE_mesh_mapping.h"
#include "BKE_mesh_remap.h"
#include "BKE_multires.h"

#include "bmesh.h"

#include <math.h>
#include <string.h>

/* number of layers to add when growing a CustomData object */
#define CUSTOMDATA_GROW 5

/* ensure typemap size is ok */
BLI_STATIC_ASSERT(sizeof(((CustomData *)NULL)->typemap) /
                  sizeof(((CustomData *)NULL)->typemap[0]) == CD_NUMTYPES,
                  "size mismatch");


/********************* Layer type information **********************/
typedef struct LayerTypeInfo {
	int size;          /* the memory size of one element of this layer's data */

	/** name of the struct used, for file writing */
	const char *structname;
	/** number of structs per element, for file writing */
	int structnum;

	/**
	 * default layer name.
	 * note! when NULL this is a way to ensure there is only ever one item
	 * see: CustomData_layertype_is_singleton() */
	const char *defaultname;

	/**
	 * a function to copy count elements of this layer's data
	 * (deep copy if appropriate)
	 * if NULL, memcpy is used
	 */
	cd_copy copy;

	/**
	 * a function to free any dynamically allocated components of this
	 * layer's data (note the data pointer itself should not be freed)
	 * size should be the size of one element of this layer's data (e.g.
	 * LayerTypeInfo.size)
	 */
	void (*free)(void *data, int count, int size);

	/**
	 * a function to interpolate between count source elements of this
	 * layer's data and store the result in dest
	 * if weights == NULL or sub_weights == NULL, they should default to 1
	 *
	 * weights gives the weight for each element in sources
	 * sub_weights gives the sub-element weights for each element in sources
	 *    (there should be (sub element count)^2 weights per element)
	 * count gives the number of elements in sources
	 *
	 * \note in some cases \a dest pointer is in \a sources
	 *       so all functions have to take this into account and delay
	 *       applying changes while reading from sources.
	 *       See bug [#32395] - Campbell.
	 */
	cd_interp interp;

	/** a function to swap the data in corners of the element */
	void (*swap)(void *data, const int *corner_indices);

	/**
	 * a function to set a layer's data to default values. if NULL, the
	 * default is assumed to be all zeros */
	void (*set_default)(void *data, int count);

	/** functions necessary for geometry collapse */
	bool (*equal)(const void *data1, const void *data2);
	void (*multiply)(void *data, float fac);
	void (*initminmax)(void *min, void *max);
	void (*add)(void *data1, const void *data2);
	void (*dominmax)(const void *data1, void *min, void *max);
	void (*copyvalue)(const void *source, void *dest, const int mixmode, const float mixfactor);

	/** a function to read data from a cdf file */
	int (*read)(CDataFile *cdf, void *data, int count);

	/** a function to write data to a cdf file */
	int (*write)(CDataFile *cdf, const void *data, int count);

	/** a function to determine file size */
	size_t (*filesize)(CDataFile *cdf, const void *data, int count);

	/** a function to determine max allowed number of layers, should be NULL or return -1 if no limit */
	int (*layers_max)(void);
} LayerTypeInfo;

static void layerCopy_mdeformvert(const void *source, void *dest,
                                  int count)
{
	int i, size = sizeof(MDeformVert);

	memcpy(dest, source, count * size);

	for (i = 0; i < count; ++i) {
		MDeformVert *dvert = POINTER_OFFSET(dest, i * size);

		if (dvert->totweight) {
			MDeformWeight *dw = MEM_mallocN(dvert->totweight * sizeof(*dw),
			                                "layerCopy_mdeformvert dw");

			memcpy(dw, dvert->dw, dvert->totweight * sizeof(*dw));
			dvert->dw = dw;
		}
		else
			dvert->dw = NULL;
	}
}

static void layerFree_mdeformvert(void *data, int count, int size)
{
	int i;

	for (i = 0; i < count; ++i) {
		MDeformVert *dvert = POINTER_OFFSET(data, i * size);

		if (dvert->dw) {
			MEM_freeN(dvert->dw);
			dvert->dw = NULL;
			dvert->totweight = 0;
		}
	}
}

/* copy just zeros in this case */
static void layerCopy_bmesh_elem_py_ptr(const void *UNUSED(source), void *dest,
                                        int count)
{
	int i, size = sizeof(void *);

	for (i = 0; i < count; ++i) {
		void **ptr = POINTER_OFFSET(dest, i * size);
		*ptr = NULL;
	}
}

#ifndef WITH_PYTHON
void bpy_bm_generic_invalidate(struct BPy_BMGeneric *UNUSED(self))
{
	/* dummy */
}
#endif

static void layerFree_bmesh_elem_py_ptr(void *data, int count, int size)
{
	int i;

	for (i = 0; i < count; ++i) {
		void **ptr = POINTER_OFFSET(data, i * size);
		if (*ptr) {
			bpy_bm_generic_invalidate(*ptr);
		}
	}
}

static void layerInterp_mdeformvert(
        const void **sources, const float *weights,
        const float *UNUSED(sub_weights), int count, void *dest)
{
	/* a single linked list of MDeformWeight's
	 * use this to avoid double allocs (which LinkNode would do) */
	struct MDeformWeight_Link {
		struct MDeformWeight_Link *next;
		MDeformWeight dw;
	};

	MDeformVert *dvert = dest;
	struct MDeformWeight_Link *dest_dwlink = NULL;
	struct MDeformWeight_Link *node;
	int i, j, totweight;

	if (count <= 0) return;

	/* build a list of unique def_nrs for dest */
	totweight = 0;
	for (i = 0; i < count; ++i) {
		const MDeformVert *source = sources[i];
		float interp_weight = weights ? weights[i] : 1.0f;

		for (j = 0; j < source->totweight; ++j) {
			MDeformWeight *dw = &source->dw[j];
			float weight = dw->weight * interp_weight;

			if (weight == 0.0f)
				continue;

			for (node = dest_dwlink; node; node = node->next) {
				MDeformWeight *tmp_dw = &node->dw;

				if (tmp_dw->def_nr == dw->def_nr) {
					tmp_dw->weight += weight;
					break;
				}
			}

			/* if this def_nr is not in the list, add it */
			if (!node) {
				struct MDeformWeight_Link *tmp_dwlink = alloca(sizeof(*tmp_dwlink));
				tmp_dwlink->dw.def_nr = dw->def_nr;
				tmp_dwlink->dw.weight = weight;

				/* inline linklist */
				tmp_dwlink->next = dest_dwlink;
				dest_dwlink = tmp_dwlink;

				totweight++;
			}
		}
	}

	/* delay writing to the destination incase dest is in sources */

	/* now we know how many unique deform weights there are, so realloc */
	if (dvert->dw && (dvert->totweight == totweight)) {
		/* pass (fastpath if we don't need to realloc) */
	}
	else {
		if (dvert->dw) {
			MEM_freeN(dvert->dw);
		}

		if (totweight) {
			dvert->dw = MEM_mallocN(sizeof(*dvert->dw) * totweight, __func__);
		}
	}

	if (totweight) {
		dvert->totweight = totweight;
		for (i = 0, node = dest_dwlink; node; node = node->next, i++) {
			dvert->dw[i] = node->dw;
		}
	}
	else {
		memset(dvert, 0, sizeof(*dvert));
	}
}

static void layerInterp_normal(
        const void **sources, const float *weights,
        const float *UNUSED(sub_weights), int count, void *dest)
{
	float no[3] = {0.0f};

	while (count--) {
		madd_v3_v3fl(no, (const float *)sources[count], weights[count]);
	}

	copy_v3_v3((float *)dest, no);
}

static void layerCopyValue_normal(const void *source, void *dest, const int mixmode, const float mixfactor)
{
	const float *no_src = source;
	float *no_dst = dest;
	float no_tmp[3];

	if (ELEM(mixmode, CDT_MIX_NOMIX, CDT_MIX_REPLACE_ABOVE_THRESHOLD, CDT_MIX_REPLACE_BELOW_THRESHOLD)) {
		/* Above/below threshold modes are not supported here, fallback to nomix (just in case). */
		copy_v3_v3(no_dst, no_src);
	}
	else {  /* Modes that support 'real' mix factor. */
		/* Since we normalize in the end, MIX and ADD are the same op here. */
		if (ELEM(mixmode, CDT_MIX_MIX, CDT_MIX_ADD)) {
			add_v3_v3v3(no_tmp, no_dst, no_src);
			normalize_v3(no_tmp);
		}
		else if (mixmode == CDT_MIX_SUB) {
			sub_v3_v3v3(no_tmp, no_dst, no_src);
			normalize_v3(no_tmp);
		}
		else if (mixmode == CDT_MIX_MUL) {
			mul_v3_v3v3(no_tmp, no_dst, no_src);
			normalize_v3(no_tmp);
		}
		else {
			copy_v3_v3(no_tmp, no_src);
		}
		interp_v3_v3v3_slerp_safe(no_dst, no_dst, no_tmp, mixfactor);
	}
}

static void layerCopy_tface(const void *source, void *dest, int count)
{
	const MTFace *source_tf = (const MTFace *)source;
	MTFace *dest_tf = (MTFace *)dest;
	int i;

	for (i = 0; i < count; ++i)
		dest_tf[i] = source_tf[i];
}

static void layerInterp_tface(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	MTFace *tf = dest;
	int i, j, k;
	float uv[4][2] = {{0.0f}};
	const float *sub_weight;

	if (count <= 0) return;

	sub_weight = sub_weights;
	for (i = 0; i < count; ++i) {
		float weight = weights ? weights[i] : 1;
		const MTFace *src = sources[i];

		for (j = 0; j < 4; ++j) {
			if (sub_weights) {
				for (k = 0; k < 4; ++k, ++sub_weight) {
					madd_v2_v2fl(uv[j], src->uv[k], (*sub_weight) * weight);
				}
			}
			else {
				madd_v2_v2fl(uv[j], src->uv[j], weight);
			}
		}
	}

	/* delay writing to the destination incase dest is in sources */
	*tf = *(MTFace *)(*sources);
	memcpy(tf->uv, uv, sizeof(tf->uv));
}

static void layerSwap_tface(void *data, const int *corner_indices)
{
	MTFace *tf = data;
	float uv[4][2];
	static const short pin_flags[4] = { TF_PIN1, TF_PIN2, TF_PIN3, TF_PIN4 };
	static const char sel_flags[4] = { TF_SEL1, TF_SEL2, TF_SEL3, TF_SEL4 };
	short unwrap = tf->unwrap & ~(TF_PIN1 | TF_PIN2 | TF_PIN3 | TF_PIN4);
	char flag = tf->flag & ~(TF_SEL1 | TF_SEL2 | TF_SEL3 | TF_SEL4);
	int j;

	for (j = 0; j < 4; ++j) {
		const int source_index = corner_indices[j];

		copy_v2_v2(uv[j], tf->uv[source_index]);

		/* swap pinning flags around */
		if (tf->unwrap & pin_flags[source_index]) {
			unwrap |= pin_flags[j];
		}

		/* swap selection flags around */
		if (tf->flag & sel_flags[source_index]) {
			flag |= sel_flags[j];
		}
	}

	memcpy(tf->uv, uv, sizeof(tf->uv));
	tf->unwrap = unwrap;
	tf->flag = flag;
}

static void layerDefault_tface(void *data, int count)
{
	static MTFace default_tf = {{{0, 0}, {1, 0}, {1, 1}, {0, 1}}, NULL,
		                        0, 0, TF_DYNAMIC | TF_CONVERTED, 0, 0};
	MTFace *tf = (MTFace *)data;
	int i;

	for (i = 0; i < count; i++)
		tf[i] = default_tf;
}

static int layerMaxNum_tface(void)
{
	return MAX_MTFACE;
}

static void layerCopy_propFloat(const void *source, void *dest,
                                int count)
{
	memcpy(dest, source, sizeof(MFloatProperty) * count);
}

static void layerCopy_propInt(const void *source, void *dest,
                              int count)
{
	memcpy(dest, source, sizeof(MIntProperty) * count);
}

static void layerCopy_propString(const void *source, void *dest,
                                 int count)
{
	memcpy(dest, source, sizeof(MStringProperty) * count);
}

static void layerCopy_origspace_face(const void *source, void *dest, int count)
{
	const OrigSpaceFace *source_tf = (const OrigSpaceFace *)source;
	OrigSpaceFace *dest_tf = (OrigSpaceFace *)dest;
	int i;

	for (i = 0; i < count; ++i)
		dest_tf[i] = source_tf[i];
}

static void layerInterp_origspace_face(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	OrigSpaceFace *osf = dest;
	int i, j, k;
	float uv[4][2] = {{0.0f}};
	const float *sub_weight;

	if (count <= 0) return;

	sub_weight = sub_weights;
	for (i = 0; i < count; ++i) {
		float weight = weights ? weights[i] : 1;
		const OrigSpaceFace *src = sources[i];

		for (j = 0; j < 4; ++j) {
			if (sub_weights) {
				for (k = 0; k < 4; ++k, ++sub_weight) {
					madd_v2_v2fl(uv[j], src->uv[k], (*sub_weight) * weight);
				}
			}
			else {
				madd_v2_v2fl(uv[j], src->uv[j], weight);
			}
		}
	}

	/* delay writing to the destination incase dest is in sources */

#if 0 /* no need, this ONLY contains UV's */
	*osf = *(OrigSpaceFace *)(*sources);
#endif
	memcpy(osf->uv, uv, sizeof(osf->uv));
}

static void layerSwap_origspace_face(void *data, const int *corner_indices)
{
	OrigSpaceFace *osf = data;
	float uv[4][2];
	int j;

	for (j = 0; j < 4; ++j) {
		copy_v2_v2(uv[j], osf->uv[corner_indices[j]]);
	}
	memcpy(osf->uv, uv, sizeof(osf->uv));
}

static void layerDefault_origspace_face(void *data, int count)
{
	static OrigSpaceFace default_osf = {{{0, 0}, {1, 0}, {1, 1}, {0, 1}}};
	OrigSpaceFace *osf = (OrigSpaceFace *)data;
	int i;

	for (i = 0; i < count; i++)
		osf[i] = default_osf;
}

static void layerSwap_mdisps(void *data, const int *ci)
{
	MDisps *s = data;
	float (*d)[3] = NULL;
	int corners, cornersize, S;

	if (s->disps) {
		int nverts = (ci[1] == 3) ? 4 : 3; /* silly way to know vertex count of face */
		corners = multires_mdisp_corners(s);
		cornersize = s->totdisp / corners;

		if (corners != nverts) {
			/* happens when face changed vertex count in edit mode
			 * if it happened, just forgot displacement */

			MEM_freeN(s->disps);
			s->totdisp = (s->totdisp / corners) * nverts;
			s->disps = MEM_callocN(s->totdisp * sizeof(float) * 3, "mdisp swap");
			return;
		}

		d = MEM_callocN(sizeof(float) * 3 * s->totdisp, "mdisps swap");

		for (S = 0; S < corners; S++)
			memcpy(d + cornersize * S, s->disps + cornersize * ci[S], cornersize * 3 * sizeof(float));
		
		MEM_freeN(s->disps);
		s->disps = d;
	}
}

static void layerCopy_mdisps(const void *source, void *dest, int count)
{
	int i;
	const MDisps *s = source;
	MDisps *d = dest;

	for (i = 0; i < count; ++i) {
		if (s[i].disps) {
			d[i].disps = MEM_dupallocN(s[i].disps);
			d[i].hidden = MEM_dupallocN(s[i].hidden);
		}
		else {
			d[i].disps = NULL;
			d[i].hidden = NULL;
		}

		/* still copy even if not in memory, displacement can be external */
		d[i].totdisp = s[i].totdisp;
		d[i].level = s[i].level;
	}
}

static void layerFree_mdisps(void *data, int count, int UNUSED(size))
{
	int i;
	MDisps *d = data;

	for (i = 0; i < count; ++i) {
		if (d[i].disps)
			MEM_freeN(d[i].disps);
		if (d[i].hidden)
			MEM_freeN(d[i].hidden);
		d[i].disps = NULL;
		d[i].hidden = NULL;
		d[i].totdisp = 0;
		d[i].level = 0;
	}
}

static int layerRead_mdisps(CDataFile *cdf, void *data, int count)
{
	MDisps *d = data;
	int i;

	for (i = 0; i < count; ++i) {
		if (!d[i].disps)
			d[i].disps = MEM_callocN(sizeof(float) * 3 * d[i].totdisp, "mdisps read");

		if (!cdf_read_data(cdf, d[i].totdisp * 3 * sizeof(float), d[i].disps)) {
			printf("failed to read multires displacement %d/%d %d\n", i, count, d[i].totdisp);
			return 0;
		}
	}

	return 1;
}

static int layerWrite_mdisps(CDataFile *cdf, const void *data, int count)
{
	const MDisps *d = data;
	int i;

	for (i = 0; i < count; ++i) {
		if (!cdf_write_data(cdf, d[i].totdisp * 3 * sizeof(float), d[i].disps)) {
			printf("failed to write multires displacement %d/%d %d\n", i, count, d[i].totdisp);
			return 0;
		}
	}

	return 1;
}

static size_t layerFilesize_mdisps(CDataFile *UNUSED(cdf), const void *data, int count)
{
	const MDisps *d = data;
	size_t size = 0;
	int i;

	for (i = 0; i < count; ++i)
		size += d[i].totdisp * 3 * sizeof(float);

	return size;
}

static void layerCopy_grid_paint_mask(const void *source, void *dest, int count)
{
	int i;
	const GridPaintMask *s = source;
	GridPaintMask *d = dest;

	for (i = 0; i < count; ++i) {
		if (s[i].data) {
			d[i].data = MEM_dupallocN(s[i].data);
			d[i].level = s[i].level;
		}
		else {
			d[i].data = NULL;
			d[i].level = 0;
		}
		
	}
}

static void layerFree_grid_paint_mask(void *data, int count, int UNUSED(size))
{
	int i;
	GridPaintMask *gpm = data;

	for (i = 0; i < count; ++i) {
		if (gpm[i].data)
			MEM_freeN(gpm[i].data);
		gpm[i].data = NULL;
		gpm[i].level = 0;
	}
}

/* --------- */
static void layerCopyValue_mloopcol(const void *source, void *dest, const int mixmode, const float mixfactor)
{
	const MLoopCol *m1 = source;
	MLoopCol *m2 = dest;
	unsigned char tmp_col[4];

	if (ELEM(mixmode, CDT_MIX_NOMIX, CDT_MIX_REPLACE_ABOVE_THRESHOLD, CDT_MIX_REPLACE_BELOW_THRESHOLD)) {
		/* Modes that do a full copy or nothing. */
		if (ELEM(mixmode, CDT_MIX_REPLACE_ABOVE_THRESHOLD, CDT_MIX_REPLACE_BELOW_THRESHOLD)) {
			/* TODO: Check for a real valid way to get 'factor' value of our dest color? */
			const float f = ((float)m2->r + (float)m2->g + (float)m2->b) / 3.0f;
			if (mixmode == CDT_MIX_REPLACE_ABOVE_THRESHOLD && f < mixfactor) {
				return;  /* Do Nothing! */
			}
			else if (mixmode == CDT_MIX_REPLACE_BELOW_THRESHOLD && f > mixfactor) {
				return;  /* Do Nothing! */
			}
		}
		m2->r = m1->r;
		m2->g = m1->g;
		m2->b = m1->b;
	}
	else {  /* Modes that support 'real' mix factor. */
		unsigned char src[4] = {m1->r, m1->g, m1->b, m1->a};
		unsigned char dst[4] = {m2->r, m2->g, m2->b, m2->a};

		if (mixmode == CDT_MIX_MIX) {
			blend_color_mix_byte(tmp_col, dst, src);
		}
		else if (mixmode == CDT_MIX_ADD) {
			blend_color_add_byte(tmp_col, dst, src);
		}
		else if (mixmode == CDT_MIX_SUB) {
			blend_color_sub_byte(tmp_col, dst, src);
		}
		else if (mixmode == CDT_MIX_MUL) {
			blend_color_mul_byte(tmp_col, dst, src);
		}
		else {
			memcpy(tmp_col, src, sizeof(tmp_col));
		}
		blend_color_interpolate_byte(dst, dst, tmp_col, mixfactor);

		m2->r = (char)dst[0];
		m2->g = (char)dst[1];
		m2->b = (char)dst[2];
	}
	m2->a = m1->a;
}

static bool layerEqual_mloopcol(const void *data1, const void *data2)
{
	const MLoopCol *m1 = data1, *m2 = data2;
	float r, g, b, a;

	r = m1->r - m2->r;
	g = m1->g - m2->g;
	b = m1->b - m2->b;
	a = m1->a - m2->a;

	return r * r + g * g + b * b + a * a < 0.001f;
}

static void layerMultiply_mloopcol(void *data, float fac)
{
	MLoopCol *m = data;

	m->r = (float)m->r * fac;
	m->g = (float)m->g * fac;
	m->b = (float)m->b * fac;
	m->a = (float)m->a * fac;
}

static void layerAdd_mloopcol(void *data1, const void *data2)
{
	MLoopCol *m = data1;
	const MLoopCol *m2 = data2;

	m->r += m2->r;
	m->g += m2->g;
	m->b += m2->b;
	m->a += m2->a;
}

static void layerDoMinMax_mloopcol(const void *data, void *vmin, void *vmax)
{
	const MLoopCol *m = data;
	MLoopCol *min = vmin, *max = vmax;

	if (m->r < min->r) min->r = m->r;
	if (m->g < min->g) min->g = m->g;
	if (m->b < min->b) min->b = m->b;
	if (m->a < min->a) min->a = m->a;
	
	if (m->r > max->r) max->r = m->r;
	if (m->g > max->g) max->g = m->g;
	if (m->b > max->b) max->b = m->b;
	if (m->a > max->a) max->a = m->a;
}

static void layerInitMinMax_mloopcol(void *vmin, void *vmax)
{
	MLoopCol *min = vmin, *max = vmax;

	min->r = 255;
	min->g = 255;
	min->b = 255;
	min->a = 255;

	max->r = 0;
	max->g = 0;
	max->b = 0;
	max->a = 0;
}

static void layerDefault_mloopcol(void *data, int count)
{
	MLoopCol default_mloopcol = {255, 255, 255, 255};
	MLoopCol *mlcol = (MLoopCol *)data;
	int i;
	for (i = 0; i < count; i++)
		mlcol[i] = default_mloopcol;

}

static void layerInterp_mloopcol(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	MLoopCol *mc = dest;
	int i;
	const float *sub_weight;
	struct {
		float a;
		float r;
		float g;
		float b;
	} col;
	col.a = col.r = col.g = col.b = 0;

	sub_weight = sub_weights;
	for (i = 0; i < count; ++i) {
		float weight = weights ? weights[i] : 1;
		const MLoopCol *src = sources[i];
		if (sub_weights) {
			col.r += src->r * (*sub_weight) * weight;
			col.g += src->g * (*sub_weight) * weight;
			col.b += src->b * (*sub_weight) * weight;
			col.a += src->a * (*sub_weight) * weight;
			sub_weight++;
		}
		else {
			col.r += src->r * weight;
			col.g += src->g * weight;
			col.b += src->b * weight;
			col.a += src->a * weight;
		}
	}
	
	/* Subdivide smooth or fractal can cause problems without clamping
	 * although weights should also not cause this situation */
	CLAMP(col.a, 0.0f, 255.0f);
	CLAMP(col.r, 0.0f, 255.0f);
	CLAMP(col.g, 0.0f, 255.0f);
	CLAMP(col.b, 0.0f, 255.0f);

	/* delay writing to the destination incase dest is in sources */
	mc->r = (int)col.r;
	mc->g = (int)col.g;
	mc->b = (int)col.b;
	mc->a = (int)col.a;
}

static int layerMaxNum_mloopcol(void)
{
	return MAX_MCOL;
}

static void layerCopyValue_mloopuv(const void *source, void *dest, const int mixmode, const float mixfactor)
{
	const MLoopUV *luv1 = source;
	MLoopUV *luv2 = dest;

	/* We only support a limited subset of advanced mixing here - namely the mixfactor interpolation. */

	if (mixmode == CDT_MIX_NOMIX) {
		copy_v2_v2(luv2->uv, luv1->uv);
	}
	else {
		interp_v2_v2v2(luv2->uv, luv2->uv, luv1->uv, mixfactor);
	}
}

static bool layerEqual_mloopuv(const void *data1, const void *data2)
{
	const MLoopUV *luv1 = data1, *luv2 = data2;

	return len_squared_v2v2(luv1->uv, luv2->uv) < 0.00001f;
}

static void layerMultiply_mloopuv(void *data, float fac)
{
	MLoopUV *luv = data;

	mul_v2_fl(luv->uv, fac);
}

static void layerInitMinMax_mloopuv(void *vmin, void *vmax)
{
	MLoopUV *min = vmin, *max = vmax;

	INIT_MINMAX2(min->uv, max->uv);
}

static void layerDoMinMax_mloopuv(const void *data, void *vmin, void *vmax)
{
	const MLoopUV *luv = data;
	MLoopUV *min = vmin, *max = vmax;

	minmax_v2v2_v2(min->uv, max->uv, luv->uv);
}

static void layerAdd_mloopuv(void *data1, const void *data2)
{
	MLoopUV *l1 = data1;
	const MLoopUV *l2 = data2;

	add_v2_v2(l1->uv, l2->uv);
}

static void layerInterp_mloopuv(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	float uv[2];
	int i;

	zero_v2(uv);

	if (sub_weights) {
		const float *sub_weight = sub_weights;
		for (i = 0; i < count; i++) {
			float weight = weights ? weights[i] : 1.0f;
			const MLoopUV *src = sources[i];
			madd_v2_v2fl(uv, src->uv, (*sub_weight) * weight);
			sub_weight++;
		}
	}
	else {
		for (i = 0; i < count; i++) {
			float weight = weights ? weights[i] : 1;
			const MLoopUV *src = sources[i];
			madd_v2_v2fl(uv, src->uv, weight);
		}
	}

	/* delay writing to the destination incase dest is in sources */
	copy_v2_v2(((MLoopUV *)dest)->uv, uv);
}

/* origspace is almost exact copy of mloopuv's, keep in sync */
static void layerCopyValue_mloop_origspace(const void *source, void *dest,
                                           const int UNUSED(mixmode), const float UNUSED(mixfactor))
{
	const OrigSpaceLoop *luv1 = source;
	OrigSpaceLoop *luv2 = dest;

	copy_v2_v2(luv2->uv, luv1->uv);
}

static bool layerEqual_mloop_origspace(const void *data1, const void *data2)
{
	const OrigSpaceLoop *luv1 = data1, *luv2 = data2;

	return len_squared_v2v2(luv1->uv, luv2->uv) < 0.00001f;
}

static void layerMultiply_mloop_origspace(void *data, float fac)
{
	OrigSpaceLoop *luv = data;

	mul_v2_fl(luv->uv, fac);
}

static void layerInitMinMax_mloop_origspace(void *vmin, void *vmax)
{
	OrigSpaceLoop *min = vmin, *max = vmax;

	INIT_MINMAX2(min->uv, max->uv);
}

static void layerDoMinMax_mloop_origspace(const void *data, void *vmin, void *vmax)
{
	const OrigSpaceLoop *luv = data;
	OrigSpaceLoop *min = vmin, *max = vmax;

	minmax_v2v2_v2(min->uv, max->uv, luv->uv);
}

static void layerAdd_mloop_origspace(void *data1, const void *data2)
{
	OrigSpaceLoop *l1 = data1;
	const OrigSpaceLoop *l2 = data2;

	add_v2_v2(l1->uv, l2->uv);
}

static void layerInterp_mloop_origspace(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	float uv[2];
	int i;

	zero_v2(uv);

	if (sub_weights) {
		const float *sub_weight = sub_weights;
		for (i = 0; i < count; i++) {
			float weight = weights ? weights[i] : 1.0f;
			const OrigSpaceLoop *src = sources[i];
			madd_v2_v2fl(uv, src->uv, (*sub_weight) * weight);
			sub_weight++;
		}
	}
	else {
		for (i = 0; i < count; i++) {
			float weight = weights ? weights[i] : 1.0f;
			const OrigSpaceLoop *src = sources[i];
			madd_v2_v2fl(uv, src->uv, weight);
		}
	}

	/* delay writing to the destination incase dest is in sources */
	copy_v2_v2(((OrigSpaceLoop *)dest)->uv, uv);
}
/* --- end copy */

static void layerInterp_mcol(
        const void **sources, const float *weights,
        const float *sub_weights, int count, void *dest)
{
	MCol *mc = dest;
	int i, j, k;
	struct {
		float a;
		float r;
		float g;
		float b;
	} col[4] = {{0.0f}};

	const float *sub_weight;

	if (count <= 0) return;
	
	sub_weight = sub_weights;
	for (i = 0; i < count; ++i) {
		float weight = weights ? weights[i] : 1;

		for (j = 0; j < 4; ++j) {
			if (sub_weights) {
				const MCol *src = sources[i];
				for (k = 0; k < 4; ++k, ++sub_weight, ++src) {
					const float w = (*sub_weight) * weight;
					col[j].a += src->a * w;
					col[j].r += src->r * w;
					col[j].g += src->g * w;
					col[j].b += src->b * w;
				}
			}
			else {
				const MCol *src = sources[i];
				col[j].a += src[j].a * weight;
				col[j].r += src[j].r * weight;
				col[j].g += src[j].g * weight;
				col[j].b += src[j].b * weight;
			}
		}
	}

	/* delay writing to the destination incase dest is in sources */
	for (j = 0; j < 4; ++j) {
		
		/* Subdivide smooth or fractal can cause problems without clamping
		 * although weights should also not cause this situation */
		CLAMP(col[j].a, 0.0f, 255.0f);
		CLAMP(col[j].r, 0.0f, 255.0f);
		CLAMP(col[j].g, 0.0f, 255.0f);
		CLAMP(col[j].b, 0.0f, 255.0f);
		
		mc[j].a = (int)col[j].a;
		mc[j].r = (int)col[j].r;
		mc[j].g = (int)col[j].g;
		mc[j].b = (int)col[j].b;
	}
}

static void layerSwap_mcol(void *data, const int *corner_indices)
{
	MCol *mcol = data;
	MCol col[4];
	int j;

	for (j = 0; j < 4; ++j)
		col[j] = mcol[corner_indices[j]];

	memcpy(mcol, col, sizeof(col));
}

static void layerDefault_mcol(void *data, int count)
{
	static MCol default_mcol = {255, 255, 255, 255};
	MCol *mcol = (MCol *)data;
	int i;

	for (i = 0; i < 4 * count; i++) {
		mcol[i] = default_mcol;
	}
}

static void layerDefault_origindex(void *data, int count)
{
	copy_vn_i((int *)data, count, ORIGINDEX_NONE);
}

static void layerInterp_bweight(
        const void **sources, const float *weights,
        const float *UNUSED(sub_weights), int count, void *dest)
{
	float f;
	float **in = (float **)sources;
	int i;
	
	if (count <= 0) return;

	f = 0.0f;

	if (weights) {
		for (i = 0; i < count; ++i) {
			f += *in[i] * weights[i];
		}
	}
	else {
		for (i = 0; i < count; ++i) {
			f += *in[i];
		}
	}

	/* delay writing to the destination incase dest is in sources */
	*((float *)dest) = f;
}

static void layerInterp_shapekey(
        const void **sources, const float *weights,
        const float *UNUSED(sub_weights), int count, void *dest)
{
	float co[3];
	float **in = (float **)sources;
	int i;

	if (count <= 0) return;

	zero_v3(co);

	if (weights) {
		for (i = 0; i < count; ++i) {
			madd_v3_v3fl(co, in[i], weights[i]);
		}
	}
	else {
		for (i = 0; i < count; ++i) {
			add_v3_v3(co, in[i]);
		}
	}

	/* delay writing to the destination incase dest is in sources */
	copy_v3_v3((float *)dest, co);
}

static void layerDefault_mvert_skin(void *data, int count)
{
	MVertSkin *vs = data;
	int i;
	
	for (i = 0; i < count; i++) {
		copy_v3_fl(vs[i].radius, 0.25f);
		vs[i].flag = 0;
	}
}

static void layerInterp_mvert_skin(
        const void **sources, const float *weights,
        const float *UNUSED(sub_weights),
        int count, void *dest)
{
	MVertSkin *vs_dst = dest;
	float radius[3], w;
	int i;

	zero_v3(radius);
	for (i = 0; i < count; i++) {
		const MVertSkin *vs_src = sources[i];
		w = weights ? weights[i] : 1.0f;

		madd_v3_v3fl(radius, vs_src->radius, w);
	}

	/* delay writing to the destination incase dest is in sources */
	vs_dst = dest;
	copy_v3_v3(vs_dst->radius, radius);
	vs_dst->flag &= ~MVERT_SKIN_ROOT;
}

static void layerSwap_flnor(void *data, const int *corner_indices)
{
	short (*flnors)[4][3] = data;
	short nors[4][3];
	int i = 4;

	while (i--) {
		copy_v3_v3_short(nors[i], (*flnors)[corner_indices[i]]);
	}

	memcpy(flnors, nors, sizeof(nors));
}

static const LayerTypeInfo LAYERTYPEINFO[CD_NUMTYPES] = {
	/* 0: CD_MVERT */
	{sizeof(MVert), "MVert", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 1: CD_MSTICKY */  /* DEPRECATED */
	{sizeof(float) * 2, "", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 2: CD_MDEFORMVERT */
	{sizeof(MDeformVert), "MDeformVert", 1, NULL, layerCopy_mdeformvert,
	 layerFree_mdeformvert, layerInterp_mdeformvert, NULL, NULL},
	/* 3: CD_MEDGE */
	{sizeof(MEdge), "MEdge", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 4: CD_MFACE */
	{sizeof(MFace), "MFace", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 5: CD_MTFACE */
	{sizeof(MTFace), "MTFace", 1, N_("UVMap"), layerCopy_tface, NULL, layerInterp_tface, layerSwap_tface,
	 layerDefault_tface, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, layerMaxNum_tface},
	/* 6: CD_MCOL */
	/* 4 MCol structs per face */
	{sizeof(MCol) * 4, "MCol", 4, N_("Col"), NULL, NULL, layerInterp_mcol,
	 layerSwap_mcol, layerDefault_mcol, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, layerMaxNum_mloopcol},
	/* 7: CD_ORIGINDEX */
	{sizeof(int), "", 0, NULL, NULL, NULL, NULL, NULL, layerDefault_origindex},
	/* 8: CD_NORMAL */
	/* 3 floats per normal vector */
	{sizeof(float) * 3, "vec3f", 1, NULL, NULL, NULL, layerInterp_normal, NULL, NULL,
	 NULL, NULL, NULL, NULL, NULL, layerCopyValue_normal},
	/* 9: CD_POLYINDEX */  /* DEPRECATED */
	{sizeof(int), "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 10: CD_PROP_FLT */
	{sizeof(MFloatProperty), "MFloatProperty", 1, N_("Float"), layerCopy_propFloat, NULL, NULL, NULL},
	/* 11: CD_PROP_INT */
	{sizeof(MIntProperty), "MIntProperty", 1, N_("Int"), layerCopy_propInt, NULL, NULL, NULL},
	/* 12: CD_PROP_STR */
	{sizeof(MStringProperty), "MStringProperty", 1, N_("String"), layerCopy_propString, NULL, NULL, NULL},
	/* 13: CD_ORIGSPACE */
	{sizeof(OrigSpaceFace), "OrigSpaceFace", 1, N_("UVMap"), layerCopy_origspace_face, NULL,
	 layerInterp_origspace_face, layerSwap_origspace_face, layerDefault_origspace_face},
	/* 14: CD_ORCO */
	{sizeof(float) * 3, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 15: CD_MTEXPOLY */
	/* note, when we expose the UV Map / TexFace split to the user, change this back to face Texture */
	{sizeof(MTexPoly), "MTexPoly", 1, N_("UVMap") /* "Face Texture" */, NULL, NULL, NULL, NULL, NULL,
	 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, layerMaxNum_tface},
	/* 16: CD_MLOOPUV */
	{sizeof(MLoopUV), "MLoopUV", 1, N_("UVMap"), NULL, NULL, layerInterp_mloopuv, NULL, NULL,
	 layerEqual_mloopuv, layerMultiply_mloopuv, layerInitMinMax_mloopuv, 
	 layerAdd_mloopuv, layerDoMinMax_mloopuv, layerCopyValue_mloopuv, NULL, NULL, NULL, layerMaxNum_tface},
	/* 17: CD_MLOOPCOL */
	{sizeof(MLoopCol), "MLoopCol", 1, N_("Col"), NULL, NULL, layerInterp_mloopcol, NULL,
	 layerDefault_mloopcol, layerEqual_mloopcol, layerMultiply_mloopcol, layerInitMinMax_mloopcol, 
	 layerAdd_mloopcol, layerDoMinMax_mloopcol, layerCopyValue_mloopcol, NULL, NULL, NULL, layerMaxNum_mloopcol},
	/* 18: CD_TANGENT */
	{sizeof(float) * 4 * 4, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 19: CD_MDISPS */
	{sizeof(MDisps), "MDisps", 1, NULL, layerCopy_mdisps,
	 layerFree_mdisps, NULL, layerSwap_mdisps, NULL,
	 NULL, NULL, NULL, NULL, NULL, NULL, 
	 layerRead_mdisps, layerWrite_mdisps, layerFilesize_mdisps},
	/* 20: CD_PREVIEW_MCOL */
	{sizeof(MCol) * 4, "MCol", 4, N_("PreviewCol"), NULL, NULL, layerInterp_mcol,
	 layerSwap_mcol, layerDefault_mcol},
	/* 21: CD_ID_MCOL */  /* DEPRECATED */
	{sizeof(MCol) * 4, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 22: CD_TEXTURE_MCOL */
	{sizeof(MCol) * 4, "MCol", 4, N_("TexturedCol"), NULL, NULL, layerInterp_mcol,
	 layerSwap_mcol, layerDefault_mcol},
	/* 23: CD_CLOTH_ORCO */
	{sizeof(float) * 3, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 24: CD_RECAST */
	{sizeof(MRecast), "MRecast", 1, N_("Recast"), NULL, NULL, NULL, NULL},

/* BMESH ONLY */
	/* 25: CD_MPOLY */
	{sizeof(MPoly), "MPoly", 1, N_("NGon Face"), NULL, NULL, NULL, NULL, NULL},
	/* 26: CD_MLOOP */
	{sizeof(MLoop), "MLoop", 1, N_("NGon Face-Vertex"), NULL, NULL, NULL, NULL, NULL},
	/* 27: CD_SHAPE_KEYINDEX */
	{sizeof(int), "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 28: CD_SHAPEKEY */
	{sizeof(float) * 3, "", 0, N_("ShapeKey"), NULL, NULL, layerInterp_shapekey},
	/* 29: CD_BWEIGHT */
	{sizeof(float), "", 0, N_("BevelWeight"), NULL, NULL, layerInterp_bweight},
	/* 30: CD_CREASE */
	{sizeof(float), "", 0, N_("SubSurfCrease"), NULL, NULL, layerInterp_bweight},
	/* 31: CD_ORIGSPACE_MLOOP */
	{sizeof(OrigSpaceLoop), "OrigSpaceLoop", 1, N_("OS Loop"), NULL, NULL, layerInterp_mloop_origspace, NULL, NULL,
	 layerEqual_mloop_origspace, layerMultiply_mloop_origspace, layerInitMinMax_mloop_origspace,
	 layerAdd_mloop_origspace, layerDoMinMax_mloop_origspace, layerCopyValue_mloop_origspace},
	/* 32: CD_PREVIEW_MLOOPCOL */
	{sizeof(MLoopCol), "MLoopCol", 1, N_("PreviewLoopCol"), NULL, NULL, layerInterp_mloopcol, NULL,
	 layerDefault_mloopcol, layerEqual_mloopcol, layerMultiply_mloopcol, layerInitMinMax_mloopcol,
	 layerAdd_mloopcol, layerDoMinMax_mloopcol, layerCopyValue_mloopcol},
	/* 33: CD_BM_ELEM_PYPTR */
	{sizeof(void *), "", 1, NULL, layerCopy_bmesh_elem_py_ptr,
	 layerFree_bmesh_elem_py_ptr, NULL, NULL, NULL},

/* END BMESH ONLY */

	/* 34: CD_PAINT_MASK */
	{sizeof(float), "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 35: CD_GRID_PAINT_MASK */
	{sizeof(GridPaintMask), "GridPaintMask", 1, NULL, layerCopy_grid_paint_mask,
	 layerFree_grid_paint_mask, NULL, NULL, NULL},
	/* 36: CD_SKIN_NODE */
	{sizeof(MVertSkin), "MVertSkin", 1, NULL, NULL, NULL,
	 layerInterp_mvert_skin, NULL, layerDefault_mvert_skin},
	/* 37: CD_FREESTYLE_EDGE */
	{sizeof(FreestyleEdge), "FreestyleEdge", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 38: CD_FREESTYLE_FACE */
	{sizeof(FreestyleFace), "FreestyleFace", 1, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 39: CD_MLOOPTANGENT */
	{sizeof(float[4]), "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
	/* 40: CD_TESSLOOPNORMAL */
	{sizeof(short[4][3]), "", 0, NULL, NULL, NULL, NULL, layerSwap_flnor, NULL},
	/* 41: CD_CUSTOMLOOPNORMAL */
	{sizeof(short[2]), "vec2s", 1, NULL, NULL, NULL, NULL, NULL, NULL},
};

/* note, numbers are from trunk and need updating for bmesh */

static const char *LAYERTYPENAMES[CD_NUMTYPES] = {
	/*   0-4 */ "CDMVert", "CDMSticky", "CDMDeformVert", "CDMEdge", "CDMFace",
	/*   5-9 */ "CDMTFace", "CDMCol", "CDOrigIndex", "CDNormal", "CDFlags",
	/* 10-14 */ "CDMFloatProperty", "CDMIntProperty", "CDMStringProperty", "CDOrigSpace", "CDOrco",
	/* 15-19 */ "CDMTexPoly", "CDMLoopUV", "CDMloopCol", "CDTangent", "CDMDisps",
	/* 20-24 */ "CDPreviewMCol", "CDIDMCol", "CDTextureMCol", "CDClothOrco", "CDMRecast",

/* BMESH ONLY */
	/* 25-29 */ "CDMPoly", "CDMLoop", "CDShapeKeyIndex", "CDShapeKey", "CDBevelWeight",
	/* 30-34 */ "CDSubSurfCrease", "CDOrigSpaceLoop", "CDPreviewLoopCol", "CDBMElemPyPtr", "CDPaintMask",
	/* 35-36 */ "CDGridPaintMask", "CDMVertSkin",
	/* 37-38 */ "CDFreestyleEdge", "CDFreestyleFace",
	/* 39-41 */ "CDMLoopTangent", "CDTessLoopNormal", "CDCustomLoopNormal",
};


const CustomDataMask CD_MASK_BAREMESH =
    CD_MASK_MVERT | CD_MASK_MEDGE | CD_MASK_MLOOP | CD_MASK_MPOLY | CD_MASK_BWEIGHT;
const CustomDataMask CD_MASK_MESH =
    CD_MASK_MVERT | CD_MASK_MEDGE |
    CD_MASK_MDEFORMVERT |
    CD_MASK_PROP_FLT | CD_MASK_PROP_INT | CD_MASK_PROP_STR | CD_MASK_MDISPS |
    CD_MASK_MLOOPUV | CD_MASK_MLOOPCOL | CD_MASK_MPOLY | CD_MASK_MLOOP |
    CD_MASK_MTEXPOLY | CD_MASK_RECAST | CD_MASK_PAINT_MASK |
    CD_MASK_GRID_PAINT_MASK | CD_MASK_MVERT_SKIN | CD_MASK_FREESTYLE_EDGE | CD_MASK_FREESTYLE_FACE |
    CD_MASK_CUSTOMLOOPNORMAL;
const CustomDataMask CD_MASK_EDITMESH =
    CD_MASK_MDEFORMVERT | CD_MASK_MLOOPUV |
    CD_MASK_MLOOPCOL | CD_MASK_MTEXPOLY | CD_MASK_SHAPE_KEYINDEX |
    CD_MASK_PROP_FLT | CD_MASK_PROP_INT | CD_MASK_PROP_STR |
    CD_MASK_MDISPS | CD_MASK_SHAPEKEY | CD_MASK_RECAST | CD_MASK_PAINT_MASK |
    CD_MASK_GRID_PAINT_MASK | CD_MASK_MVERT_SKIN | CD_MASK_CUSTOMLOOPNORMAL;
const CustomDataMask CD_MASK_DERIVEDMESH =
    CD_MASK_MDEFORMVERT |
    CD_MASK_PROP_FLT | CD_MASK_PROP_INT | CD_MASK_CLOTH_ORCO |
    CD_MASK_MLOOPUV | CD_MASK_MLOOPCOL | CD_MASK_MTEXPOLY | CD_MASK_PREVIEW_MLOOPCOL |
    CD_MASK_PROP_STR | CD_MASK_ORIGSPACE | CD_MASK_ORIGSPACE_MLOOP | CD_MASK_ORCO | CD_MASK_TANGENT |
    CD_MASK_PREVIEW_MCOL | CD_MASK_SHAPEKEY | CD_MASK_RECAST |
    CD_MASK_ORIGINDEX | CD_MASK_MVERT_SKIN | CD_MASK_FREESTYLE_EDGE | CD_MASK_FREESTYLE_FACE |
    CD_MASK_CUSTOMLOOPNORMAL;
const CustomDataMask CD_MASK_BMESH =
    CD_MASK_MLOOPUV | CD_MASK_MLOOPCOL | CD_MASK_MTEXPOLY |
    CD_MASK_MDEFORMVERT | CD_MASK_PROP_FLT | CD_MASK_PROP_INT |
    CD_MASK_PROP_STR | CD_MASK_SHAPEKEY | CD_MASK_SHAPE_KEYINDEX | CD_MASK_MDISPS |
    CD_MASK_CREASE | CD_MASK_BWEIGHT | CD_MASK_RECAST | CD_MASK_PAINT_MASK |
    CD_MASK_GRID_PAINT_MASK | CD_MASK_MVERT_SKIN | CD_MASK_FREESTYLE_EDGE | CD_MASK_FREESTYLE_FACE |
    CD_MASK_CUSTOMLOOPNORMAL;
const CustomDataMask CD_MASK_FACECORNERS =  /* XXX Not used anywhere! */
    CD_MASK_MTFACE | CD_MASK_MCOL | CD_MASK_MTEXPOLY | CD_MASK_MLOOPUV |
    CD_MASK_MLOOPCOL | CD_MASK_NORMAL | CD_MASK_MLOOPTANGENT;
const CustomDataMask CD_MASK_EVERYTHING =
    CD_MASK_MVERT | CD_MASK_MDEFORMVERT | CD_MASK_MEDGE | CD_MASK_MFACE |
    CD_MASK_MTFACE | CD_MASK_MCOL | CD_MASK_ORIGINDEX | CD_MASK_NORMAL /* | CD_MASK_POLYINDEX */ | CD_MASK_PROP_FLT |
    CD_MASK_PROP_INT | CD_MASK_PROP_STR | CD_MASK_ORIGSPACE | CD_MASK_ORCO | CD_MASK_MTEXPOLY | CD_MASK_MLOOPUV |
    CD_MASK_MLOOPCOL | CD_MASK_TANGENT | CD_MASK_MDISPS | CD_MASK_PREVIEW_MCOL | CD_MASK_CLOTH_ORCO | CD_MASK_RECAST |
    /* BMESH ONLY START */
    CD_MASK_MPOLY | CD_MASK_MLOOP | CD_MASK_SHAPE_KEYINDEX | CD_MASK_SHAPEKEY | CD_MASK_BWEIGHT | CD_MASK_CREASE |
    CD_MASK_ORIGSPACE_MLOOP | CD_MASK_PREVIEW_MLOOPCOL | CD_MASK_BM_ELEM_PYPTR |
    /* BMESH ONLY END */
    CD_MASK_PAINT_MASK | CD_MASK_GRID_PAINT_MASK | CD_MASK_MVERT_SKIN |
    CD_MASK_FREESTYLE_EDGE | CD_MASK_FREESTYLE_FACE |
    CD_MASK_MLOOPTANGENT | CD_MASK_TESSLOOPNORMAL | CD_MASK_CUSTOMLOOPNORMAL;

static const LayerTypeInfo *layerType_getInfo(int type)
{
	if (type < 0 || type >= CD_NUMTYPES) return NULL;

	return &LAYERTYPEINFO[type];
}

static const char *layerType_getName(int type)
{
	if (type < 0 || type >= CD_NUMTYPES) return NULL;

	return LAYERTYPENAMES[type];
}

void customData_mask_layers__print(CustomDataMask mask)
{
	int i;

	printf("mask=0x%lx:\n", (long unsigned int)mask);
	for (i = 0; i < CD_NUMTYPES; i++) {
		if (mask & CD_TYPE_AS_MASK(i)) {
			printf("  %s\n", layerType_getName(i));
		}
	}
}

/********************* CustomData functions *********************/
static void customData_update_offsets(CustomData *data);

static CustomDataLayer *customData_add_layer__internal(CustomData *data, int type, int alloctype, void *layerdata,
                                                       int totelem, const char *name);

void CustomData_update_typemap(CustomData *data)
{
	int i, lasttype = -1;

	for (i = 0; i < CD_NUMTYPES; i++) {
		data->typemap[i] = -1;
	}

	for (i = 0; i < data->totlayer; i++) {
		const int type = data->layers[i].type;
		if (type != lasttype) {
			data->typemap[type] = i;
			lasttype = type;
		}
	}
}

/* currently only used in BLI_assert */
#ifndef NDEBUG
static bool customdata_typemap_is_valid(const CustomData *data)
{
	CustomData data_copy = *data;
	CustomData_update_typemap(&data_copy);
	return (memcmp(data->typemap, data_copy.typemap, sizeof(data->typemap)) == 0);
}
#endif

bool CustomData_merge(const struct CustomData *source, struct CustomData *dest,
                      CustomDataMask mask, int alloctype, int totelem)
{
	/*const LayerTypeInfo *typeInfo;*/
	CustomDataLayer *layer, *newlayer;
	void *data;
	int i, type, lasttype = -1, lastactive = 0, lastrender = 0, lastclone = 0, lastmask = 0, flag = 0;
	int number = 0, maxnumber = -1;
	bool changed = false;

	for (i = 0; i < source->totlayer; ++i) {
		layer = &source->layers[i];
		/*typeInfo = layerType_getInfo(layer->type);*/ /*UNUSED*/

		type = layer->type;
		flag = layer->flag;

		if (type != lasttype) {
			number = 0;
			maxnumber = CustomData_layertype_layers_max(type);
			lastactive = layer->active;
			lastrender = layer->active_rnd;
			lastclone = layer->active_clone;
			lastmask = layer->active_mask;
			lasttype = type;
		}
		else
			number++;

		if (flag & CD_FLAG_NOCOPY) continue;
		else if (!(mask & CD_TYPE_AS_MASK(type))) continue;
		else if ((maxnumber != -1) && (number >= maxnumber)) continue;
		else if (CustomData_get_layer_named(dest, type, layer->name)) continue;

		switch (alloctype) {
			case CD_ASSIGN:
			case CD_REFERENCE:
			case CD_DUPLICATE:
				data = layer->data;
				break;
			default:
				data = NULL;
				break;
		}

		if ((alloctype == CD_ASSIGN) && (flag & CD_FLAG_NOFREE)) {
			newlayer = customData_add_layer__internal(dest, type, CD_REFERENCE, data, totelem, layer->name);
		}
		else {
			newlayer = customData_add_layer__internal(dest, type, alloctype, data, totelem, layer->name);
		}
		
		if (newlayer) {
			newlayer->uid = layer->uid;
			
			newlayer->active = lastactive;
			newlayer->active_rnd = lastrender;
			newlayer->active_clone = lastclone;
			newlayer->active_mask = lastmask;
			newlayer->flag |= flag & (CD_FLAG_EXTERNAL | CD_FLAG_IN_MEMORY);
			changed = true;
		}
	}

	CustomData_update_typemap(dest);
	return changed;
}

/* NOTE: Take care of referenced layers by yourself! */
void CustomData_realloc(CustomData *data, int totelem)
{
	int i;
	for (i = 0; i < data->totlayer; ++i) {
		CustomDataLayer *layer = &data->layers[i];
		const LayerTypeInfo *typeInfo;
		int size;
		if (layer->flag & CD_FLAG_NOFREE) {
			continue;
		}
		typeInfo = layerType_getInfo(layer->type);
		size = totelem * typeInfo->size;
		layer->data = MEM_reallocN(layer->data, size);
	}
}

void CustomData_copy(const struct CustomData *source, struct CustomData *dest,
                     CustomDataMask mask, int alloctype, int totelem)
{
	CustomData_reset(dest);

	if (source->external)
		dest->external = MEM_dupallocN(source->external);

	CustomData_merge(source, dest, mask, alloctype, totelem);
}

static void customData_free_layer__internal(CustomDataLayer *layer, int totelem)
{
	const LayerTypeInfo *typeInfo;

	if (!(layer->flag & CD_FLAG_NOFREE) && layer->data) {
		typeInfo = layerType_getInfo(layer->type);

		if (typeInfo->free)
			typeInfo->free(layer->data, totelem, typeInfo->size);

		if (layer->data)
			MEM_freeN(layer->data);
	}
}

static void CustomData_external_free(CustomData *data)
{
	if (data->external) {
		MEM_freeN(data->external);
		data->external = NULL;
	}
}

void CustomData_reset(CustomData *data)
{
	memset(data, 0, sizeof(*data));
	copy_vn_i(data->typemap, CD_NUMTYPES, -1);
}

void CustomData_free(CustomData *data, int totelem)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		customData_free_layer__internal(&data->layers[i], totelem);

	if (data->layers)
		MEM_freeN(data->layers);
	
	CustomData_external_free(data);
	CustomData_reset(data);
}

void CustomData_free_typemask(struct CustomData *data, int totelem, CustomDataMask mask)
{
	int i;

	for (i = 0; i < data->totlayer; ++i) {
		CustomDataLayer *layer = &data->layers[i];
		if (!(mask & CD_TYPE_AS_MASK(layer->type))) {
			continue;
		}
		customData_free_layer__internal(layer, totelem);
	}

	if (data->layers)
		MEM_freeN(data->layers);

	CustomData_external_free(data);
	CustomData_reset(data);
}

static void customData_update_offsets(CustomData *data)
{
	const LayerTypeInfo *typeInfo;
	int i, offset = 0;

	for (i = 0; i < data->totlayer; ++i) {
		typeInfo = layerType_getInfo(data->layers[i].type);

		data->layers[i].offset = offset;
		offset += typeInfo->size;
	}

	data->totsize = offset;
	CustomData_update_typemap(data);
}

/* to use when we're in the middle of modifying layers */
static int CustomData_get_layer_index__notypemap(const CustomData *data, int type)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			return i;

	return -1;
}

/* -------------------------------------------------------------------- */
/* index values to access the layers (offset from the layer start) */

int CustomData_get_layer_index(const CustomData *data, int type)
{
	BLI_assert(customdata_typemap_is_valid(data));
	return data->typemap[type];
}

int CustomData_get_layer_index_n(const struct CustomData *data, int type, int n)
{
	int i = CustomData_get_layer_index(data, type);

	if (i != -1) {
		BLI_assert(i + n < data->totlayer);
		i = (data->layers[i + n].type == type) ? (i + n) : (-1);
	}

	return i;
}

int CustomData_get_named_layer_index(const CustomData *data, int type, const char *name)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			if (STREQ(data->layers[i].name, name))
				return i;

	return -1;
}

int CustomData_get_active_layer_index(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? layer_index + data->layers[layer_index].active : -1;
}

int CustomData_get_render_layer_index(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? layer_index + data->layers[layer_index].active_rnd : -1;
}

int CustomData_get_clone_layer_index(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? layer_index + data->layers[layer_index].active_clone : -1;
}

int CustomData_get_stencil_layer_index(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? layer_index + data->layers[layer_index].active_mask : -1;
}


/* -------------------------------------------------------------------- */
/* index values per layer type */

int CustomData_get_named_layer(const struct CustomData *data, int type, const char *name)
{
	const int named_index = CustomData_get_named_layer_index(data, type, name);
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (named_index != -1) ? named_index - layer_index : -1;
}

int CustomData_get_active_layer(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? data->layers[layer_index].active : -1;
}

int CustomData_get_render_layer(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? data->layers[layer_index].active_rnd : -1;
}

int CustomData_get_clone_layer(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? data->layers[layer_index].active_clone : -1;
}

int CustomData_get_stencil_layer(const CustomData *data, int type)
{
	const int layer_index = data->typemap[type];
	BLI_assert(customdata_typemap_is_valid(data));
	return (layer_index != -1) ? data->layers[layer_index].active_mask : -1;
}

void CustomData_set_layer_active(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active = n;
}

void CustomData_set_layer_render(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_rnd = n;
}

void CustomData_set_layer_clone(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_clone = n;
}

void CustomData_set_layer_stencil(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_mask = n;
}

/* for using with an index from CustomData_get_active_layer_index and CustomData_get_render_layer_index */
void CustomData_set_layer_active_index(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active = n - i;
}

void CustomData_set_layer_render_index(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_rnd = n - i;
}

void CustomData_set_layer_clone_index(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_clone = n - i;
}

void CustomData_set_layer_stencil_index(CustomData *data, int type, int n)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].active_mask = n - i;
}

void CustomData_set_layer_flag(struct CustomData *data, int type, int flag)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (data->layers[i].type == type)
			data->layers[i].flag |= flag;
}

static int customData_resize(CustomData *data, int amount)
{
	CustomDataLayer *tmp = MEM_callocN(sizeof(*tmp) * (data->maxlayer + amount),
	                                   "CustomData->layers");
	if (!tmp) return 0;

	data->maxlayer += amount;
	if (data->layers) {
		memcpy(tmp, data->layers, sizeof(*tmp) * data->totlayer);
		MEM_freeN(data->layers);
	}
	data->layers = tmp;

	return 1;
}

static CustomDataLayer *customData_add_layer__internal(CustomData *data, int type, int alloctype, void *layerdata,
                                                       int totelem, const char *name)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);
	const int size = totelem * typeInfo->size;
	int flag = 0, index = data->totlayer;
	void *newlayerdata = NULL;

	/* Passing a layerdata to copy from with an alloctype that won't copy is
	 * most likely a bug */
	BLI_assert(!layerdata ||
	           (alloctype == CD_ASSIGN) ||
	           (alloctype == CD_DUPLICATE) ||
	           (alloctype == CD_REFERENCE));

	BLI_assert(size >= 0);

	if (!typeInfo->defaultname && CustomData_has_layer(data, type))
		return &data->layers[CustomData_get_layer_index(data, type)];

	if ((alloctype == CD_ASSIGN) || (alloctype == CD_REFERENCE)) {
		newlayerdata = layerdata;
	}
	else if (size > 0) {
		if (alloctype == CD_DUPLICATE && layerdata) {
			newlayerdata = MEM_mallocN(size, layerType_getName(type));
		}
		else {
			newlayerdata = MEM_callocN(size, layerType_getName(type));
		}

		if (!newlayerdata)
			return NULL;
	}

	if (alloctype == CD_DUPLICATE && layerdata) {
		if (typeInfo->copy)
			typeInfo->copy(layerdata, newlayerdata, totelem);
		else
			memcpy(newlayerdata, layerdata, size);
	}
	else if (alloctype == CD_DEFAULT) {
		if (typeInfo->set_default)
			typeInfo->set_default(newlayerdata, totelem);
	}
	else if (alloctype == CD_REFERENCE)
		flag |= CD_FLAG_NOFREE;

	if (index >= data->maxlayer) {
		if (!customData_resize(data, CUSTOMDATA_GROW)) {
			if (newlayerdata != layerdata)
				MEM_freeN(newlayerdata);
			return NULL;
		}
	}
	
	data->totlayer++;

	/* keep layers ordered by type */
	for (; index > 0 && data->layers[index - 1].type > type; --index)
		data->layers[index] = data->layers[index - 1];

	data->layers[index].type = type;
	data->layers[index].flag = flag;
	data->layers[index].data = newlayerdata;

	if (name || (name = DATA_(typeInfo->defaultname))) {
		BLI_strncpy(data->layers[index].name, name, sizeof(data->layers[index].name));
		CustomData_set_layer_unique_name(data, index);
	}
	else
		data->layers[index].name[0] = '\0';

	if (index > 0 && data->layers[index - 1].type == type) {
		data->layers[index].active = data->layers[index - 1].active;
		data->layers[index].active_rnd = data->layers[index - 1].active_rnd;
		data->layers[index].active_clone = data->layers[index - 1].active_clone;
		data->layers[index].active_mask = data->layers[index - 1].active_mask;
	}
	else {
		data->layers[index].active = 0;
		data->layers[index].active_rnd = 0;
		data->layers[index].active_clone = 0;
		data->layers[index].active_mask = 0;
	}
	
	customData_update_offsets(data);

	return &data->layers[index];
}

void *CustomData_add_layer(CustomData *data, int type, int alloctype,
                           void *layerdata, int totelem)
{
	CustomDataLayer *layer;
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);
	
	layer = customData_add_layer__internal(data, type, alloctype, layerdata,
	                                       totelem, typeInfo->defaultname);
	CustomData_update_typemap(data);

	if (layer)
		return layer->data;

	return NULL;
}

/*same as above but accepts a name*/
void *CustomData_add_layer_named(CustomData *data, int type, int alloctype,
                                 void *layerdata, int totelem, const char *name)
{
	CustomDataLayer *layer;
	
	layer = customData_add_layer__internal(data, type, alloctype, layerdata,
	                                       totelem, name);
	CustomData_update_typemap(data);

	if (layer)
		return layer->data;

	return NULL;
}


bool CustomData_free_layer(CustomData *data, int type, int totelem, int index)
{
	const int n = index - CustomData_get_layer_index(data, type);
	int i;
	
	if (index < 0)
		return false;

	customData_free_layer__internal(&data->layers[index], totelem);

	for (i = index + 1; i < data->totlayer; ++i)
		data->layers[i - 1] = data->layers[i];

	data->totlayer--;

	/* if layer was last of type in array, set new active layer */
	i = CustomData_get_layer_index__notypemap(data, type);

	if (i != -1) {
		/* don't decrement zero index */
		const int index_nonzero = n ? n : 1;
		CustomDataLayer *layer;

		for (layer = &data->layers[i]; i < data->totlayer && layer->type == type; i++, layer++) {
			if (layer->active       >= index_nonzero) layer->active--;
			if (layer->active_rnd   >= index_nonzero) layer->active_rnd--;
			if (layer->active_clone >= index_nonzero) layer->active_clone--;
			if (layer->active_mask  >= index_nonzero) layer->active_mask--;
		}
	}

	if (data->totlayer <= data->maxlayer - CUSTOMDATA_GROW)
		customData_resize(data, -CUSTOMDATA_GROW);

	customData_update_offsets(data);

	return true;
}

bool CustomData_free_layer_active(CustomData *data, int type, int totelem)
{
	int index = 0;
	index = CustomData_get_active_layer_index(data, type);
	if (index == -1)
		return false;
	return CustomData_free_layer(data, type, totelem, index);
}


void CustomData_free_layers(CustomData *data, int type, int totelem)
{
	while (CustomData_has_layer(data, type))
		CustomData_free_layer_active(data, type, totelem);
}

bool CustomData_has_layer(const CustomData *data, int type)
{
	return (CustomData_get_layer_index(data, type) != -1);
}

int CustomData_number_of_layers(const CustomData *data, int type)
{
	int i, number = 0;

	for (i = 0; i < data->totlayer; i++)
		if (data->layers[i].type == type)
			number++;
	
	return number;
}

int CustomData_number_of_layers_typemask(const CustomData *data, CustomDataMask mask)
{
	int i, number = 0;

	for (i = 0; i < data->totlayer; i++)
		if (mask & CD_TYPE_AS_MASK(data->layers[i].type))
			number++;

	return number;
}

static void *customData_duplicate_referenced_layer_index(CustomData *data, const int layer_index, const int totelem)
{
	CustomDataLayer *layer;

	if (layer_index == -1) {
		return NULL;
	}

	layer = &data->layers[layer_index];

	if (layer->flag & CD_FLAG_NOFREE) {
		/* MEM_dupallocN won't work in case of complex layers, like e.g.
		 * CD_MDEFORMVERT, which has pointers to allocated data...
		 * So in case a custom copy function is defined, use it!
		 */
		const LayerTypeInfo *typeInfo = layerType_getInfo(layer->type);

		if (typeInfo->copy) {
			void *dst_data = MEM_mallocN(totelem * typeInfo->size, "CD duplicate ref layer");
			typeInfo->copy(layer->data, dst_data, totelem);
			layer->data = dst_data;
		}
		else {
			layer->data = MEM_dupallocN(layer->data);
		}

		layer->flag &= ~CD_FLAG_NOFREE;
	}

	return layer->data;
}

void *CustomData_duplicate_referenced_layer(CustomData *data, const int type, const int totelem)
{
	int layer_index;

	/* get the layer index of the first layer of type */
	layer_index = CustomData_get_active_layer_index(data, type);

	return customData_duplicate_referenced_layer_index(data, layer_index, totelem);
}

void *CustomData_duplicate_referenced_layer_n(CustomData *data, const int type, const int n, const int totelem)
{
	int layer_index;

	/* get the layer index of the desired layer */
	layer_index = CustomData_get_layer_index_n(data, type, n);

	return customData_duplicate_referenced_layer_index(data, layer_index, totelem);
}

void *CustomData_duplicate_referenced_layer_named(CustomData *data, const int type, const char *name, const int totelem)
{
	int layer_index;

	/* get the layer index of the desired layer */
	layer_index = CustomData_get_named_layer_index(data, type, name);

	return customData_duplicate_referenced_layer_index(data, layer_index, totelem);
}

bool CustomData_is_referenced_layer(struct CustomData *data, int type)
{
	CustomDataLayer *layer;
	int layer_index;

	/* get the layer index of the first layer of type */
	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1)
		return false;

	layer = &data->layers[layer_index];

	return (layer->flag & CD_FLAG_NOFREE) != 0;
}

void CustomData_free_temporary(CustomData *data, int totelem)
{
	CustomDataLayer *layer;
	int i, j;
	bool changed = false;

	for (i = 0, j = 0; i < data->totlayer; ++i) {
		layer = &data->layers[i];

		if (i != j)
			data->layers[j] = data->layers[i];

		if ((layer->flag & CD_FLAG_TEMPORARY) == CD_FLAG_TEMPORARY) {
			customData_free_layer__internal(layer, totelem);
			changed = true;
		}
		else
			j++;
	}

	data->totlayer = j;

	if (data->totlayer <= data->maxlayer - CUSTOMDATA_GROW) {
		customData_resize(data, -CUSTOMDATA_GROW);
		changed = true;
	}

	if (changed) {
		customData_update_offsets(data);
	}
}

void CustomData_set_only_copy(const struct CustomData *data,
                              CustomDataMask mask)
{
	int i;

	for (i = 0; i < data->totlayer; ++i)
		if (!(mask & CD_TYPE_AS_MASK(data->layers[i].type)))
			data->layers[i].flag |= CD_FLAG_NOCOPY;
}

void CustomData_copy_elements(int type, void *src_data_ofs, void *dst_data_ofs, int count)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->copy)
		typeInfo->copy(src_data_ofs, dst_data_ofs, count);
	else
		memcpy(dst_data_ofs, src_data_ofs, count * typeInfo->size);
}

static void CustomData_copy_data_layer(
        const CustomData *source, CustomData *dest,
        int src_i, int dst_i,
        int src_index, int dst_index, int count)
{
	const LayerTypeInfo *typeInfo;
	int src_offset;
	int dst_offset;

	const void *src_data = source->layers[src_i].data;
	void *dst_data = dest->layers[dst_i].data;

	typeInfo = layerType_getInfo(source->layers[src_i].type);

	src_offset = src_index * typeInfo->size;
	dst_offset = dst_index * typeInfo->size;

	if (!count || !src_data || !dst_data) {
		if (count && !(src_data == NULL && dst_data == NULL)) {
			printf("%s: warning null data for %s type (%p --> %p), skipping\n",
				   __func__, layerType_getName(source->layers[src_i].type),
				   (void *)src_data, (void *)dst_data);
		}
		return;
	}

	if (typeInfo->copy)
		typeInfo->copy(POINTER_OFFSET(src_data, src_offset),
		               POINTER_OFFSET(dst_data, dst_offset),
		               count);
	else
		memcpy(POINTER_OFFSET(dst_data, dst_offset),
		       POINTER_OFFSET(src_data, src_offset),
		       count * typeInfo->size);
}

void CustomData_copy_data_named(const CustomData *source, CustomData *dest,
                                int source_index, int dest_index, int count)
{
	int src_i, dest_i;

	/* copies a layer at a time */
	for (src_i = 0; src_i < source->totlayer; ++src_i) {

		dest_i = CustomData_get_named_layer_index(dest, source->layers[src_i].type, source->layers[src_i].name);

		/* if we found a matching layer, copy the data */
		if (dest_i != -1) {
			CustomData_copy_data_layer(source, dest, src_i, dest_i, source_index, dest_index, count);
		}
	}
}

void CustomData_copy_data(const CustomData *source, CustomData *dest,
                          int source_index, int dest_index, int count)
{
	int src_i, dest_i;

	/* copies a layer at a time */
	dest_i = 0;
	for (src_i = 0; src_i < source->totlayer; ++src_i) {

		/* find the first dest layer with type >= the source type
		 * (this should work because layers are ordered by type)
		 */
		while (dest_i < dest->totlayer && dest->layers[dest_i].type < source->layers[src_i].type) {
			dest_i++;
		}

		/* if there are no more dest layers, we're done */
		if (dest_i >= dest->totlayer) return;

		/* if we found a matching layer, copy the data */
		if (dest->layers[dest_i].type == source->layers[src_i].type) {
			CustomData_copy_data_layer(source, dest, src_i, dest_i, source_index, dest_index, count);
			
			/* if there are multiple source & dest layers of the same type,
			 * we don't want to copy all source layers to the same dest, so
			 * increment dest_i
			 */
			dest_i++;
		}
	}
}

void CustomData_free_elem(CustomData *data, int index, int count)
{
	int i;
	const LayerTypeInfo *typeInfo;

	for (i = 0; i < data->totlayer; ++i) {
		if (!(data->layers[i].flag & CD_FLAG_NOFREE)) {
			typeInfo = layerType_getInfo(data->layers[i].type);

			if (typeInfo->free) {
				int offset = index * typeInfo->size;

				typeInfo->free(POINTER_OFFSET(data->layers[i].data, offset), count, typeInfo->size);
			}
		}
	}
}

#define SOURCE_BUF_SIZE 100

void CustomData_interp(const CustomData *source, CustomData *dest,
                       int *src_indices, float *weights, float *sub_weights,
                       int count, int dest_index)
{
	int src_i, dest_i;
	int j;
	const void *source_buf[SOURCE_BUF_SIZE];
	const void **sources = source_buf;

	/* slow fallback in case we're interpolating a ridiculous number of
	 * elements
	 */
	if (count > SOURCE_BUF_SIZE)
		sources = MEM_mallocN(sizeof(*sources) * count, __func__);

	/* interpolates a layer at a time */
	dest_i = 0;
	for (src_i = 0; src_i < source->totlayer; ++src_i) {
		const LayerTypeInfo *typeInfo = layerType_getInfo(source->layers[src_i].type);
		if (!typeInfo->interp) continue;

		/* find the first dest layer with type >= the source type
		 * (this should work because layers are ordered by type)
		 */
		while (dest_i < dest->totlayer && dest->layers[dest_i].type < source->layers[src_i].type) {
			dest_i++;
		}

		/* if there are no more dest layers, we're done */
		if (dest_i >= dest->totlayer) break;

		/* if we found a matching layer, copy the data */
		if (dest->layers[dest_i].type == source->layers[src_i].type) {
			void *src_data = source->layers[src_i].data;

			for (j = 0; j < count; ++j) {
				sources[j] = POINTER_OFFSET(src_data, src_indices[j] * typeInfo->size);
			}

			typeInfo->interp(sources, weights, sub_weights, count,
			                 POINTER_OFFSET(dest->layers[dest_i].data, dest_index * typeInfo->size));

			/* if there are multiple source & dest layers of the same type,
			 * we don't want to copy all source layers to the same dest, so
			 * increment dest_i
			 */
			dest_i++;
		}
	}

	if (count > SOURCE_BUF_SIZE) MEM_freeN((void *)sources);
}

void CustomData_swap(struct CustomData *data, int index, const int *corner_indices)
{
	const LayerTypeInfo *typeInfo;
	int i;

	for (i = 0; i < data->totlayer; ++i) {
		typeInfo = layerType_getInfo(data->layers[i].type);

		if (typeInfo->swap) {
			const int offset = index * typeInfo->size;

			typeInfo->swap(POINTER_OFFSET(data->layers[i].data, offset), corner_indices);
		}
	}
}

void *CustomData_get(const CustomData *data, int index, int type)
{
	int offset;
	int layer_index;
	
	BLI_assert(index >= 0);

	/* get the layer index of the active layer of type */
	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return NULL;

	/* get the offset of the desired element */
	offset = layerType_getInfo(type)->size * index;

	return POINTER_OFFSET(data->layers[layer_index].data, offset);
}

void *CustomData_get_n(const CustomData *data, int type, int index, int n)
{
	int layer_index;
	int offset;

	BLI_assert(index >= 0 && n >= 0);

	/* get the layer index of the first layer of type */
	layer_index = data->typemap[type];
	if (layer_index == -1) return NULL;

	offset = layerType_getInfo(type)->size * index;
	return POINTER_OFFSET(data->layers[layer_index + n].data, offset);
}

void *CustomData_get_layer(const CustomData *data, int type)
{
	/* get the layer index of the active layer of type */
	int layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return NULL;

	return data->layers[layer_index].data;
}

void *CustomData_get_layer_n(const CustomData *data, int type, int n)
{
	/* get the layer index of the active layer of type */
	int layer_index = CustomData_get_layer_index_n(data, type, n);
	if (layer_index == -1) return NULL;

	return data->layers[layer_index].data;
}

void *CustomData_get_layer_named(const struct CustomData *data, int type,
                                 const char *name)
{
	int layer_index = CustomData_get_named_layer_index(data, type, name);
	if (layer_index == -1) return NULL;

	return data->layers[layer_index].data;
}

int CustomData_get_offset(const CustomData *data, int type)
{
	/* get the layer index of the active layer of type */
	int layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return -1;

	return data->layers[layer_index].offset;
}

int CustomData_get_n_offset(const CustomData *data, int type, int n)
{
	/* get the layer index of the active layer of type */
	int layer_index = CustomData_get_layer_index_n(data, type, n);
	if (layer_index == -1) return -1;

	return data->layers[layer_index].offset;
}

bool CustomData_set_layer_name(const CustomData *data, int type, int n, const char *name)
{
	/* get the layer index of the first layer of type */
	const int layer_index = CustomData_get_layer_index_n(data, type, n);

	if ((layer_index == -1) || !name)
		return false;
	
	BLI_strncpy(data->layers[layer_index].name, name, sizeof(data->layers[layer_index].name));
	
	return true;
}

const char *CustomData_get_layer_name(const CustomData *data, int type, int n)
{
	const int layer_index = CustomData_get_layer_index_n(data, type, n);

	return (layer_index == -1) ? NULL : data->layers[layer_index].name;
}

void *CustomData_set_layer(const CustomData *data, int type, void *ptr)
{
	/* get the layer index of the first layer of type */
	int layer_index = CustomData_get_active_layer_index(data, type);

	if (layer_index == -1) return NULL;

	data->layers[layer_index].data = ptr;

	return ptr;
}

void *CustomData_set_layer_n(const struct CustomData *data, int type, int n, void *ptr)
{
	/* get the layer index of the first layer of type */
	int layer_index = CustomData_get_layer_index_n(data, type, n);
	if (layer_index == -1) return NULL;

	data->layers[layer_index].data = ptr;

	return ptr;
}

void CustomData_set(const CustomData *data, int index, int type, const void *source)
{
	void *dest = CustomData_get(data, index, type);
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (!dest) return;

	if (typeInfo->copy)
		typeInfo->copy(source, dest, 1);
	else
		memcpy(dest, source, typeInfo->size);
}

/* BMesh functions */
/* needed to convert to/from different face reps */
void CustomData_to_bmeshpoly(CustomData *fdata, CustomData *pdata, CustomData *ldata,
                             int totloop, int totpoly)
{
	int i;
	for (i = 0; i < fdata->totlayer; i++) {
		if (fdata->layers[i].type == CD_MTFACE) {
			CustomData_add_layer_named(pdata, CD_MTEXPOLY, CD_CALLOC, NULL, totpoly, fdata->layers[i].name);
			CustomData_add_layer_named(ldata, CD_MLOOPUV, CD_CALLOC, NULL, totloop, fdata->layers[i].name);
		}
		else if (fdata->layers[i].type == CD_MCOL) {
			CustomData_add_layer_named(ldata, CD_MLOOPCOL, CD_CALLOC, NULL, totloop, fdata->layers[i].name);
		}
		else if (fdata->layers[i].type == CD_MDISPS) {
			CustomData_add_layer_named(ldata, CD_MDISPS, CD_CALLOC, NULL, totloop, fdata->layers[i].name);
		}
		else if (fdata->layers[i].type == CD_TESSLOOPNORMAL) {
			CustomData_add_layer_named(ldata, CD_NORMAL, CD_CALLOC, NULL, totloop, fdata->layers[i].name);
		}
	}
}

void CustomData_from_bmeshpoly(CustomData *fdata, CustomData *pdata, CustomData *ldata, int total)
{
	int i;

	/* avoid accumulating extra layers */
	BLI_assert(!CustomData_from_bmeshpoly_test(fdata, pdata, ldata, false));

	for (i = 0; i < pdata->totlayer; i++) {
		if (pdata->layers[i].type == CD_MTEXPOLY) {
			CustomData_add_layer_named(fdata, CD_MTFACE, CD_CALLOC, NULL, total, pdata->layers[i].name);
		}
	}
	for (i = 0; i < ldata->totlayer; i++) {
		if (ldata->layers[i].type == CD_MLOOPCOL) {
			CustomData_add_layer_named(fdata, CD_MCOL, CD_CALLOC, NULL, total, ldata->layers[i].name);
		}
		else if (ldata->layers[i].type == CD_PREVIEW_MLOOPCOL) {
			CustomData_add_layer_named(fdata, CD_PREVIEW_MCOL, CD_CALLOC, NULL, total, ldata->layers[i].name);
		}
		else if (ldata->layers[i].type == CD_ORIGSPACE_MLOOP) {
			CustomData_add_layer_named(fdata, CD_ORIGSPACE, CD_CALLOC, NULL, total, ldata->layers[i].name);
		}
		else if (ldata->layers[i].type == CD_NORMAL) {
			CustomData_add_layer_named(fdata, CD_TESSLOOPNORMAL, CD_CALLOC, NULL, total, ldata->layers[i].name);
		}
		else if (ldata->layers[i].type == CD_TANGENT) {
			CustomData_add_layer_named(fdata, CD_TANGENT, CD_CALLOC, NULL, total, ldata->layers[i].name);
		}
	}

	CustomData_bmesh_update_active_layers(fdata, pdata, ldata);
}

#ifndef NDEBUG
/**
 * Debug check, used to assert when we expect layers to be in/out of sync.
 *
 * \param fallback: Use when there are no layers to handle,
 * since callers may expect success or failure.
 */
bool CustomData_from_bmeshpoly_test(CustomData *fdata, CustomData *pdata, CustomData *ldata, bool fallback)
{
	int a_num = 0, b_num = 0;
#define LAYER_CMP(l_a, t_a, l_b, t_b) \
	((a_num += CustomData_number_of_layers(l_a, t_a)) == (b_num += CustomData_number_of_layers(l_b, t_b)))

	if (!LAYER_CMP(pdata, CD_MTEXPOLY, fdata, CD_MTFACE))
		return false;
	if (!LAYER_CMP(ldata, CD_MLOOPCOL, fdata, CD_MCOL))
		return false;
	if (!LAYER_CMP(ldata, CD_PREVIEW_MLOOPCOL, fdata, CD_PREVIEW_MCOL))
		return false;
	if (!LAYER_CMP(ldata, CD_ORIGSPACE_MLOOP, fdata, CD_ORIGSPACE))
		return false;
	if (!LAYER_CMP(ldata, CD_NORMAL, fdata, CD_TESSLOOPNORMAL))
		return false;
	if (!LAYER_CMP(ldata, CD_TANGENT, fdata, CD_TANGENT))
		return false;

#undef TEST_RET

	/* if no layers are on either CustomData's,
	 * then there was nothing to do... */
	return a_num ? true : fallback;
}
#endif


void CustomData_bmesh_update_active_layers(CustomData *fdata, CustomData *pdata, CustomData *ldata)
{
	int act;

	if (CustomData_has_layer(pdata, CD_MTEXPOLY)) {
		act = CustomData_get_active_layer(pdata, CD_MTEXPOLY);
		CustomData_set_layer_active(ldata, CD_MLOOPUV, act);
		CustomData_set_layer_active(fdata, CD_MTFACE, act);

		act = CustomData_get_render_layer(pdata, CD_MTEXPOLY);
		CustomData_set_layer_render(ldata, CD_MLOOPUV, act);
		CustomData_set_layer_render(fdata, CD_MTFACE, act);

		act = CustomData_get_clone_layer(pdata, CD_MTEXPOLY);
		CustomData_set_layer_clone(ldata, CD_MLOOPUV, act);
		CustomData_set_layer_clone(fdata, CD_MTFACE, act);

		act = CustomData_get_stencil_layer(pdata, CD_MTEXPOLY);
		CustomData_set_layer_stencil(ldata, CD_MLOOPUV, act);
		CustomData_set_layer_stencil(fdata, CD_MTFACE, act);
	}

	if (CustomData_has_layer(ldata, CD_MLOOPCOL)) {
		act = CustomData_get_active_layer(ldata, CD_MLOOPCOL);
		CustomData_set_layer_active(fdata, CD_MCOL, act);

		act = CustomData_get_render_layer(ldata, CD_MLOOPCOL);
		CustomData_set_layer_render(fdata, CD_MCOL, act);

		act = CustomData_get_clone_layer(ldata, CD_MLOOPCOL);
		CustomData_set_layer_clone(fdata, CD_MCOL, act);

		act = CustomData_get_stencil_layer(ldata, CD_MLOOPCOL);
		CustomData_set_layer_stencil(fdata, CD_MCOL, act);
	}
}

/* update active indices for active/render/clone/stencil custom data layers
 * based on indices from fdata layers
 * used by do_versions in readfile.c when creating pdata and ldata for pre-bmesh
 * meshes and needed to preserve active/render/clone/stencil flags set in pre-bmesh files
 */
void CustomData_bmesh_do_versions_update_active_layers(CustomData *fdata, CustomData *pdata, CustomData *ldata)
{
	int act;

	if (CustomData_has_layer(fdata, CD_MTFACE)) {
		act = CustomData_get_active_layer(fdata, CD_MTFACE);
		CustomData_set_layer_active(pdata, CD_MTEXPOLY, act);
		CustomData_set_layer_active(ldata, CD_MLOOPUV, act);

		act = CustomData_get_render_layer(fdata, CD_MTFACE);
		CustomData_set_layer_render(pdata, CD_MTEXPOLY, act);
		CustomData_set_layer_render(ldata, CD_MLOOPUV, act);

		act = CustomData_get_clone_layer(fdata, CD_MTFACE);
		CustomData_set_layer_clone(pdata, CD_MTEXPOLY, act);
		CustomData_set_layer_clone(ldata, CD_MLOOPUV, act);

		act = CustomData_get_stencil_layer(fdata, CD_MTFACE);
		CustomData_set_layer_stencil(pdata, CD_MTEXPOLY, act);
		CustomData_set_layer_stencil(ldata, CD_MLOOPUV, act);
	}

	if (CustomData_has_layer(fdata, CD_MCOL)) {
		act = CustomData_get_active_layer(fdata, CD_MCOL);
		CustomData_set_layer_active(ldata, CD_MLOOPCOL, act);

		act = CustomData_get_render_layer(fdata, CD_MCOL);
		CustomData_set_layer_render(ldata, CD_MLOOPCOL, act);

		act = CustomData_get_clone_layer(fdata, CD_MCOL);
		CustomData_set_layer_clone(ldata, CD_MLOOPCOL, act);

		act = CustomData_get_stencil_layer(fdata, CD_MCOL);
		CustomData_set_layer_stencil(ldata, CD_MLOOPCOL, act);
	}
}

void CustomData_bmesh_init_pool(CustomData *data, int totelem, const char htype)
{
	int chunksize;

	/* Dispose old pools before calling here to avoid leaks */
	BLI_assert(data->pool == NULL);

	switch (htype) {
		case BM_VERT: chunksize = bm_mesh_chunksize_default.totvert;  break;
		case BM_EDGE: chunksize = bm_mesh_chunksize_default.totedge;  break;
		case BM_LOOP: chunksize = bm_mesh_chunksize_default.totloop;  break;
		case BM_FACE: chunksize = bm_mesh_chunksize_default.totface;  break;
		default:
			BLI_assert(0);
			chunksize = 512;
			break;
	}

	/* If there are no layers, no pool is needed just yet */
	if (data->totlayer) {
		data->pool = BLI_mempool_create(data->totsize, totelem, chunksize, BLI_MEMPOOL_NOP);
	}
}

bool CustomData_bmesh_merge(
        const CustomData *source, CustomData *dest,
        CustomDataMask mask, int alloctype, BMesh *bm, const char htype)
{
	BMHeader *h;
	BMIter iter;
	CustomData destold;
	void *tmp;
	int iter_type;
	int totelem;

	if (CustomData_number_of_layers_typemask(source, mask) == 0) {
		return false;
	}

	/* copy old layer description so that old data can be copied into
	 * the new allocation */
	destold = *dest;
	if (destold.layers) {
		destold.layers = MEM_dupallocN(destold.layers);
	}

	if (CustomData_merge(source, dest, mask, alloctype, 0) == false) {
		if (destold.layers)
			MEM_freeN(destold.layers);
		return false;
	}

	switch (htype) {
		case BM_VERT:
			iter_type = BM_VERTS_OF_MESH;
			totelem = bm->totvert;
			break;
		case BM_EDGE:
			iter_type = BM_EDGES_OF_MESH;
			totelem = bm->totedge;
			break;
		case BM_LOOP:
			iter_type = BM_LOOPS_OF_FACE;
			totelem = bm->totloop;
			break;
		case BM_FACE:
			iter_type = BM_FACES_OF_MESH;
			totelem = bm->totface;
			break;
		default: /* should never happen */
			BLI_assert(!"invalid type given");
			iter_type = BM_VERTS_OF_MESH;
			totelem = bm->totvert;
			break;
	}

	dest->pool = NULL;
	CustomData_bmesh_init_pool(dest, totelem, htype);

	if (iter_type != BM_LOOPS_OF_FACE) {
		/*ensure all current elements follow new customdata layout*/
		BM_ITER_MESH (h, &iter, bm, iter_type) {
			tmp = NULL;
			CustomData_bmesh_copy_data(&destold, dest, h->data, &tmp);
			CustomData_bmesh_free_block(&destold, &h->data);
			h->data = tmp;
		}
	}
	else {
		BMFace *f;
		BMLoop *l;
		BMIter liter;

		/*ensure all current elements follow new customdata layout*/
		BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
			BM_ITER_ELEM (l, &liter, f, BM_LOOPS_OF_FACE) {
				tmp = NULL;
				CustomData_bmesh_copy_data(&destold, dest, l->head.data, &tmp);
				CustomData_bmesh_free_block(&destold, &l->head.data);
				l->head.data = tmp;
			}
		}
	}

	if (destold.pool) BLI_mempool_destroy(destold.pool);
	if (destold.layers) MEM_freeN(destold.layers);
	return true;
}

void CustomData_bmesh_free_block(CustomData *data, void **block)
{
	const LayerTypeInfo *typeInfo;
	int i;

	if (*block == NULL)
		return;

	for (i = 0; i < data->totlayer; ++i) {
		if (!(data->layers[i].flag & CD_FLAG_NOFREE)) {
			typeInfo = layerType_getInfo(data->layers[i].type);

			if (typeInfo->free) {
				int offset = data->layers[i].offset;
				typeInfo->free(POINTER_OFFSET(*block, offset), 1, typeInfo->size);
			}
		}
	}

	if (data->totsize)
		BLI_mempool_free(data->pool, *block);

	*block = NULL;
}

/**
 * Same as #CustomData_bmesh_free_block but zero the memory rather then freeing.
 */
void CustomData_bmesh_free_block_data(CustomData *data, void *block)
{
	const LayerTypeInfo *typeInfo;
	int i;

	if (block == NULL)
		return;

	for (i = 0; i < data->totlayer; ++i) {
		if (!(data->layers[i].flag & CD_FLAG_NOFREE)) {
			typeInfo = layerType_getInfo(data->layers[i].type);

			if (typeInfo->free) {
				int offset = data->layers[i].offset;
				typeInfo->free(POINTER_OFFSET(block, offset), 1, typeInfo->size);
			}
		}
	}

	if (data->totsize)
		memset(block, 0, data->totsize);
}

static void CustomData_bmesh_alloc_block(CustomData *data, void **block)
{

	if (*block)
		CustomData_bmesh_free_block(data, block);

	if (data->totsize > 0)
		*block = BLI_mempool_alloc(data->pool);
	else
		*block = NULL;
}

void CustomData_bmesh_copy_data(const CustomData *source, CustomData *dest,
                                void *src_block, void **dest_block)
{
	const LayerTypeInfo *typeInfo;
	int dest_i, src_i;

	if (*dest_block == NULL) {
		CustomData_bmesh_alloc_block(dest, dest_block);
		if (*dest_block)
			memset(*dest_block, 0, dest->totsize);
	}
	
	/* copies a layer at a time */
	dest_i = 0;
	for (src_i = 0; src_i < source->totlayer; ++src_i) {

		/* find the first dest layer with type >= the source type
		 * (this should work because layers are ordered by type)
		 */
		while (dest_i < dest->totlayer && dest->layers[dest_i].type < source->layers[src_i].type) {
			dest_i++;
		}

		/* if there are no more dest layers, we're done */
		if (dest_i >= dest->totlayer) return;

		/* if we found a matching layer, copy the data */
		if (dest->layers[dest_i].type == source->layers[src_i].type &&
		    STREQ(dest->layers[dest_i].name, source->layers[src_i].name))
		{
			const void *src_data = POINTER_OFFSET(src_block, source->layers[src_i].offset);
			void *dest_data = POINTER_OFFSET(*dest_block, dest->layers[dest_i].offset);

			typeInfo = layerType_getInfo(source->layers[src_i].type);

			if (typeInfo->copy)
				typeInfo->copy(src_data, dest_data, 1);
			else
				memcpy(dest_data, src_data, typeInfo->size);

			/* if there are multiple source & dest layers of the same type,
			 * we don't want to copy all source layers to the same dest, so
			 * increment dest_i
			 */
			dest_i++;
		}
	}
}

/*Bmesh Custom Data Functions. Should replace editmesh ones with these as well, due to more effecient memory alloc*/
void *CustomData_bmesh_get(const CustomData *data, void *block, int type)
{
	int layer_index;
	
	/* get the layer index of the first layer of type */
	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return NULL;

	return POINTER_OFFSET(block, data->layers[layer_index].offset);
}

void *CustomData_bmesh_get_n(const CustomData *data, void *block, int type, int n)
{
	int layer_index;
	
	/* get the layer index of the first layer of type */
	layer_index = CustomData_get_layer_index(data, type);
	if (layer_index == -1) return NULL;

	return POINTER_OFFSET(block, data->layers[layer_index + n].offset);
}

/*gets from the layer at physical index n, note: doesn't check type.*/
void *CustomData_bmesh_get_layer_n(const CustomData *data, void *block, int n)
{
	if (n < 0 || n >= data->totlayer) return NULL;

	return POINTER_OFFSET(block, data->layers[n].offset);
}

bool CustomData_layer_has_math(const struct CustomData *data, int layer_n)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(data->layers[layer_n].type);
	
	if (typeInfo->equal && typeInfo->add && typeInfo->multiply && 
	    typeInfo->initminmax && typeInfo->dominmax)
	{
		return true;
	}
	
	return false;
}

bool CustomData_layer_has_interp(const struct CustomData *data, int layer_n)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(data->layers[layer_n].type);

	if (typeInfo->interp) {
		return true;
	}

	return false;
}

bool CustomData_has_math(const struct CustomData *data)
{
	int i;

	/* interpolates a layer at a time */
	for (i = 0; i < data->totlayer; ++i) {
		if (CustomData_layer_has_math(data, i)) {
			return true;
		}
	}

	return false;
}

/* a non bmesh version would have to check layer->data */
bool CustomData_bmesh_has_free(const struct CustomData *data)
{
	const LayerTypeInfo *typeInfo;
	int i;

	for (i = 0; i < data->totlayer; ++i) {
		if (!(data->layers[i].flag & CD_FLAG_NOFREE)) {
			typeInfo = layerType_getInfo(data->layers[i].type);
			if (typeInfo->free) {
				return true;
			}
		}
	}
	return false;
}

bool CustomData_has_interp(const struct CustomData *data)
{
	int i;

	/* interpolates a layer at a time */
	for (i = 0; i < data->totlayer; ++i) {
		if (CustomData_layer_has_interp(data, i)) {
			return true;
		}
	}

	return false;
}

bool CustomData_has_referenced(const struct CustomData *data)
{
	int i;
	for (i = 0; i < data->totlayer; ++i) {
		if (data->layers[i].flag & CD_FLAG_NOFREE) {
			return true;
		}
	}
	return false;
}

/* copies the "value" (e.g. mloopuv uv or mloopcol colors) from one block to
 * another, while not overwriting anything else (e.g. flags)*/
void CustomData_data_copy_value(int type, const void *source, void *dest)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (!dest) return;

	if (typeInfo->copyvalue)
		typeInfo->copyvalue(source, dest, CDT_MIX_NOMIX, 0.0f);
	else
		memcpy(dest, source, typeInfo->size);
}

/* Mixes the "value" (e.g. mloopuv uv or mloopcol colors) from one block into
 * another, while not overwriting anything else (e.g. flags)*/
void CustomData_data_mix_value(int type, const void *source, void *dest, const int mixmode, const float mixfactor)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (!dest) return;

	if (typeInfo->copyvalue) {
		typeInfo->copyvalue(source, dest, mixmode, mixfactor);
	}
	else {
		/* Mere copy if no advanced interpolation is supported. */
		memcpy(dest, source, typeInfo->size);
	}
}

bool CustomData_data_equals(int type, const void *data1, const void *data2)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->equal)
		return typeInfo->equal(data1, data2);
	else return !memcmp(data1, data2, typeInfo->size);
}

void CustomData_data_initminmax(int type, void *min, void *max)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->initminmax)
		typeInfo->initminmax(min, max);
}


void CustomData_data_dominmax(int type, const void *data, void *min, void *max)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->dominmax)
		typeInfo->dominmax(data, min, max);
}


void CustomData_data_multiply(int type, void *data, float fac)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->multiply)
		typeInfo->multiply(data, fac);
}


void CustomData_data_add(int type, void *data1, const void *data2)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (typeInfo->add)
		typeInfo->add(data1, data2);
}

void CustomData_bmesh_set(const CustomData *data, void *block, int type, const void *source)
{
	void *dest = CustomData_bmesh_get(data, block, type);
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (!dest) return;

	if (typeInfo->copy)
		typeInfo->copy(source, dest, 1);
	else
		memcpy(dest, source, typeInfo->size);
}

void CustomData_bmesh_set_n(CustomData *data, void *block, int type, int n, const void *source)
{
	void *dest = CustomData_bmesh_get_n(data, block, type, n);
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	if (!dest) return;

	if (typeInfo->copy)
		typeInfo->copy(source, dest, 1);
	else
		memcpy(dest, source, typeInfo->size);
}

void CustomData_bmesh_set_layer_n(CustomData *data, void *block, int n, const void *source)
{
	void *dest = CustomData_bmesh_get_layer_n(data, block, n);
	const LayerTypeInfo *typeInfo = layerType_getInfo(data->layers[n].type);

	if (!dest) return;

	if (typeInfo->copy)
		typeInfo->copy(source, dest, 1);
	else
		memcpy(dest, source, typeInfo->size);
}

/**
 * \note src_blocks_ofs & dst_block_ofs
 * must be pointers to the data, offset by layer->offset already.
 */
void CustomData_bmesh_interp_n(
        CustomData *data, const void **src_blocks_ofs,
        const float *weights, const float *sub_weights,
        int count, void *dst_block_ofs, int n)
{
	CustomDataLayer *layer = &data->layers[n];
	const LayerTypeInfo *typeInfo = layerType_getInfo(layer->type);

	typeInfo->interp(src_blocks_ofs, weights, sub_weights, count, dst_block_ofs);
}

void CustomData_bmesh_interp(
        CustomData *data, const void **src_blocks,
        const float *weights, const float *sub_weights,
        int count, void *dst_block)
{
	int i, j;
	void *source_buf[SOURCE_BUF_SIZE];
	const void **sources = (const void **)source_buf;

	/* slow fallback in case we're interpolating a ridiculous number of
	 * elements
	 */
	if (count > SOURCE_BUF_SIZE)
		sources = MEM_mallocN(sizeof(*sources) * count, __func__);

	/* interpolates a layer at a time */
	for (i = 0; i < data->totlayer; ++i) {
		CustomDataLayer *layer = &data->layers[i];
		const LayerTypeInfo *typeInfo = layerType_getInfo(layer->type);
		if (typeInfo->interp) {
			for (j = 0; j < count; ++j) {
				sources[j] = POINTER_OFFSET(src_blocks[j], layer->offset);
			}
			CustomData_bmesh_interp_n(
			        data, sources,
			        weights, sub_weights, count,
			        POINTER_OFFSET(dst_block, layer->offset), i);
		}
	}

	if (count > SOURCE_BUF_SIZE) MEM_freeN((void *)sources);
}

static void CustomData_bmesh_set_default_n(CustomData *data, void **block, int n)
{
	const LayerTypeInfo *typeInfo;
	int offset = data->layers[n].offset;

	typeInfo = layerType_getInfo(data->layers[n].type);

	if (typeInfo->set_default) {
		typeInfo->set_default(POINTER_OFFSET(*block, offset), 1);
	}
	else {
		memset(POINTER_OFFSET(*block, offset), 0, typeInfo->size);
	}
}

void CustomData_bmesh_set_default(CustomData *data, void **block)
{
	int i;

	if (*block == NULL)
		CustomData_bmesh_alloc_block(data, block);

	for (i = 0; i < data->totlayer; ++i) {
		CustomData_bmesh_set_default_n(data, block, i);
	}
}

/**
 * \param use_default_init initializes data which can't be copied,
 * typically you'll want to use this if the BM_xxx create function
 * is called with BM_CREATE_SKIP_CD flag
 */
void CustomData_to_bmesh_block(const CustomData *source, CustomData *dest,
                               int src_index, void **dest_block, bool use_default_init)
{
	const LayerTypeInfo *typeInfo;
	int dest_i, src_i, src_offset;

	if (*dest_block == NULL)
		CustomData_bmesh_alloc_block(dest, dest_block);
	
	/* copies a layer at a time */
	dest_i = 0;
	for (src_i = 0; src_i < source->totlayer; ++src_i) {

		/* find the first dest layer with type >= the source type
		 * (this should work because layers are ordered by type)
		 */
		while (dest_i < dest->totlayer && dest->layers[dest_i].type < source->layers[src_i].type) {
			if (use_default_init) {
				CustomData_bmesh_set_default_n(dest, dest_block, dest_i);
			}
			dest_i++;
		}

		/* if there are no more dest layers, we're done */
		if (dest_i >= dest->totlayer) break;

		/* if we found a matching layer, copy the data */
		if (dest->layers[dest_i].type == source->layers[src_i].type) {
			int offset = dest->layers[dest_i].offset;
			const void *src_data = source->layers[src_i].data;
			void *dest_data = POINTER_OFFSET(*dest_block, offset);

			typeInfo = layerType_getInfo(dest->layers[dest_i].type);
			src_offset = src_index * typeInfo->size;

			if (typeInfo->copy)
				typeInfo->copy(POINTER_OFFSET(src_data, src_offset), dest_data, 1);
			else
				memcpy(dest_data, POINTER_OFFSET(src_data, src_offset), typeInfo->size);

			/* if there are multiple source & dest layers of the same type,
			 * we don't want to copy all source layers to the same dest, so
			 * increment dest_i
			 */
			dest_i++;
		}
	}

	if (use_default_init) {
		while (dest_i < dest->totlayer) {
			CustomData_bmesh_set_default_n(dest, dest_block, dest_i);
			dest_i++;
		}
	}
}

void CustomData_from_bmesh_block(const CustomData *source, CustomData *dest,
                                 void *src_block, int dst_index)
{
	int dest_i, src_i;

	/* copies a layer at a time */
	dest_i = 0;
	for (src_i = 0; src_i < source->totlayer; ++src_i) {

		/* find the first dest layer with type >= the source type
		 * (this should work because layers are ordered by type)
		 */
		while (dest_i < dest->totlayer && dest->layers[dest_i].type < source->layers[src_i].type) {
			dest_i++;
		}

		/* if there are no more dest layers, we're done */
		if (dest_i >= dest->totlayer) return;

		/* if we found a matching layer, copy the data */
		if (dest->layers[dest_i].type == source->layers[src_i].type) {
			const LayerTypeInfo *typeInfo = layerType_getInfo(dest->layers[dest_i].type);
			int offset = source->layers[src_i].offset;
			const void *src_data = POINTER_OFFSET(src_block, offset);
			void *dst_data = POINTER_OFFSET(dest->layers[dest_i].data, dst_index * typeInfo->size);

			if (typeInfo->copy)
				typeInfo->copy(src_data, dst_data, 1);
			else
				memcpy(dst_data, src_data, typeInfo->size);

			/* if there are multiple source & dest layers of the same type,
			 * we don't want to copy all source layers to the same dest, so
			 * increment dest_i
			 */
			dest_i++;
		}
	}

}

void CustomData_file_write_info(int type, const char **structname, int *structnum)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	*structname = typeInfo->structname;
	*structnum = typeInfo->structnum;
}

/**
 * Prepare given custom data for file writing.
 *
 * \param data the customdata to tweak for .blend file writing (modified in place).
 * \param r_write_layers contains a reduced set of layers to be written to file, use it with writestruct_at_address()
 *                       (caller must free it if != \a write_layers_buff).
 * \param write_layers_buff an optional buffer for r_write_layers (to avoid allocating it).
 * \param write_layers_size the size of pre-allocated \a write_layer_buff.
 *
 * \warning After this func has ran, given custom data is no more valid from Blender PoV (its totlayer is invalid).
 *          This func shall always be called with localized data (as it is in write_meshes()).
 * \note data->typemap is not updated here, since it is always rebuilt on file read anyway. This means written
 *       typemap does not match written layers (as returned by \a r_write_layers). Trivial to fix is ever needed.
 */
void CustomData_file_write_prepare(
        CustomData *data,
        CustomDataLayer **r_write_layers, CustomDataLayer *write_layers_buff, size_t write_layers_size)
{
	CustomDataLayer *write_layers = write_layers_buff;
	const size_t chunk_size = (write_layers_size > 0) ? write_layers_size : CD_TEMP_CHUNK_SIZE;

	const int totlayer = data->totlayer;
	int i, j;

	for (i = 0, j = 0; i < totlayer; i++) {
		CustomDataLayer *layer = &data->layers[i];
		if (layer->flag & CD_FLAG_NOCOPY) {  /* Layers with this flag set are not written to file. */
			data->totlayer--;
			/* printf("%s: skipping layer %p (%s)\n", __func__, layer, layer->name); */
		}
		else {
			if (UNLIKELY((size_t)j >= write_layers_size)) {
				if (write_layers == write_layers_buff) {
					write_layers = MEM_mallocN(sizeof(*write_layers) * (write_layers_size + chunk_size), __func__);
					if (write_layers_buff) {
						memcpy(write_layers, write_layers_buff, sizeof(*write_layers) * write_layers_size);
					}
				}
				else {
					write_layers = MEM_reallocN(write_layers, sizeof(*write_layers) * (write_layers_size + chunk_size));
				}
				write_layers_size += chunk_size;
			}
			write_layers[j++] = *layer;
		}
	}
	BLI_assert(j == data->totlayer);
	data->maxlayer = data->totlayer;  /* We only write that much of data! */
	*r_write_layers = write_layers;
}

int CustomData_sizeof(int type)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	return typeInfo->size;
}

const char *CustomData_layertype_name(int type)
{
	return layerType_getName(type);
}


/**
 * Can only ever be one of these.
 */
bool CustomData_layertype_is_singleton(int type)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);
	return typeInfo->defaultname == NULL;
}

/**
 * \return Maximum number of layers of given \a type, -1 means 'no limit'.
 */
int CustomData_layertype_layers_max(const int type)
{
	const LayerTypeInfo *typeInfo = layerType_getInfo(type);

	/* Same test as for singleton above. */
	if (typeInfo->defaultname == NULL) {
		return 1;
	}
	else if (typeInfo->layers_max == NULL) {
		return -1;
	}

	return typeInfo->layers_max();
}

static bool CustomData_is_property_layer(int type)
{
	if ((type == CD_PROP_FLT) || (type == CD_PROP_INT) || (type == CD_PROP_STR))
		return true;
	return false;
}

static bool cd_layer_find_dupe(CustomData *data, const char *name, int type, int index)
{
	int i;
	/* see if there is a duplicate */
	for (i = 0; i < data->totlayer; i++) {
		if (i != index) {
			CustomDataLayer *layer = &data->layers[i];
			
			if (CustomData_is_property_layer(type)) {
				if (CustomData_is_property_layer(layer->type) && STREQ(layer->name, name)) {
					return true;
				}
			}
			else {
				if (i != index && layer->type == type && STREQ(layer->name, name)) {
					return true;
				}
			}
		}
	}
	
	return false;
}

static bool customdata_unique_check(void *arg, const char *name)
{
	struct {CustomData *data; int type; int index; } *data_arg = arg;
	return cd_layer_find_dupe(data_arg->data, name, data_arg->type, data_arg->index);
}

void CustomData_set_layer_unique_name(CustomData *data, int index)
{	
	CustomDataLayer *nlayer = &data->layers[index];
	const LayerTypeInfo *typeInfo = layerType_getInfo(nlayer->type);

	struct {CustomData *data; int type; int index; } data_arg;
	data_arg.data = data;
	data_arg.type = nlayer->type;
	data_arg.index = index;

	if (!typeInfo->defaultname)
		return;

	BLI_uniquename_cb(customdata_unique_check, &data_arg, DATA_(typeInfo->defaultname), '.', nlayer->name,
	                  sizeof(nlayer->name));
}

void CustomData_validate_layer_name(const CustomData *data, int type, const char *name, char *outname)
{
	int index = -1;

	/* if a layer name was given, try to find that layer */
	if (name[0])
		index = CustomData_get_named_layer_index(data, type, name);

	if (index == -1) {
		/* either no layer was specified, or the layer we want has been
		 * deleted, so assign the active layer to name
		 */
		index = CustomData_get_active_layer_index(data, type);
		BLI_strncpy(outname, data->layers[index].name, MAX_CUSTOMDATA_LAYER_NAME);
	}
	else {
		BLI_strncpy(outname, name, MAX_CUSTOMDATA_LAYER_NAME);
	}
}

bool CustomData_verify_versions(struct CustomData *data, int index)
{
	const LayerTypeInfo *typeInfo;
	CustomDataLayer *layer = &data->layers[index];
	bool keeplayer = true;
	int i;

	if (layer->type >= CD_NUMTYPES) {
		keeplayer = false; /* unknown layer type from future version */
	}
	else {
		typeInfo = layerType_getInfo(layer->type);

		if (!typeInfo->defaultname && (index > 0) &&
		    data->layers[index - 1].type == layer->type)
		{
			keeplayer = false; /* multiple layers of which we only support one */
		}
	}

	if (!keeplayer) {
		for (i = index + 1; i < data->totlayer; ++i)
			data->layers[i - 1] = data->layers[i];
		data->totlayer--;
	}

	return keeplayer;
}

/****************************** External Files *******************************/

static void customdata_external_filename(char filename[FILE_MAX], ID *id, CustomDataExternal *external)
{
	BLI_strncpy(filename, external->filename, FILE_MAX);
	BLI_path_abs(filename, ID_BLEND_PATH(G.main, id));
}

void CustomData_external_reload(CustomData *data, ID *UNUSED(id), CustomDataMask mask, int totelem)
{
	CustomDataLayer *layer;
	const LayerTypeInfo *typeInfo;
	int i;

	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if (!(mask & CD_TYPE_AS_MASK(layer->type))) {
			/* pass */
		}
		else if ((layer->flag & CD_FLAG_EXTERNAL) && (layer->flag & CD_FLAG_IN_MEMORY)) {
			if (typeInfo->free)
				typeInfo->free(layer->data, totelem, typeInfo->size);
			layer->flag &= ~CD_FLAG_IN_MEMORY;
		}
	}
}

void CustomData_external_read(CustomData *data, ID *id, CustomDataMask mask, int totelem)
{
	CustomDataExternal *external = data->external;
	CustomDataLayer *layer;
	CDataFile *cdf;
	CDataFileLayer *blay;
	char filename[FILE_MAX];
	const LayerTypeInfo *typeInfo;
	int i, update = 0;

	if (!external)
		return;
	
	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if (!(mask & CD_TYPE_AS_MASK(layer->type))) {
			/* pass */
		}
		else if (layer->flag & CD_FLAG_IN_MEMORY) {
			/* pass */
		}
		else if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->read) {
			update = 1;
		}
	}

	if (!update)
		return;

	customdata_external_filename(filename, id, external);

	cdf = cdf_create(CDF_TYPE_MESH);
	if (!cdf_read_open(cdf, filename)) {
		fprintf(stderr, "Failed to read %s layer from %s.\n", layerType_getName(layer->type), filename);
		return;
	}

	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if (!(mask & CD_TYPE_AS_MASK(layer->type))) {
			/* pass */
		}
		else if (layer->flag & CD_FLAG_IN_MEMORY) {
			/* pass */
		}
		else if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->read) {
			blay = cdf_layer_find(cdf, layer->type, layer->name);

			if (blay) {
				if (cdf_read_layer(cdf, blay)) {
					if (typeInfo->read(cdf, layer->data, totelem)) {
						/* pass */
					}
					else {
						break;
					}
					layer->flag |= CD_FLAG_IN_MEMORY;
				}
				else
					break;
			}
		}
	}

	cdf_read_close(cdf);
	cdf_free(cdf);
}

void CustomData_external_write(CustomData *data, ID *id, CustomDataMask mask, int totelem, int free)
{
	CustomDataExternal *external = data->external;
	CustomDataLayer *layer;
	CDataFile *cdf;
	CDataFileLayer *blay;
	const LayerTypeInfo *typeInfo;
	int i, update = 0;
	char filename[FILE_MAX];

	if (!external)
		return;

	/* test if there is anything to write */
	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if (!(mask & CD_TYPE_AS_MASK(layer->type))) {
			/* pass */
		}
		else if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->write) {
			update = 1;
		}
	}

	if (!update)
		return;

	/* make sure data is read before we try to write */
	CustomData_external_read(data, id, mask, totelem);
	customdata_external_filename(filename, id, external);

	cdf = cdf_create(CDF_TYPE_MESH);

	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->filesize) {
			if (layer->flag & CD_FLAG_IN_MEMORY) {
				cdf_layer_add(cdf, layer->type, layer->name,
				              typeInfo->filesize(cdf, layer->data, totelem));
			}
			else {
				cdf_free(cdf);
				return; /* read failed for a layer! */
			}
		}
	}

	if (!cdf_write_open(cdf, filename)) {
		fprintf(stderr, "Failed to open %s for writing.\n", filename);
		return;
	}

	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->write) {
			blay = cdf_layer_find(cdf, layer->type, layer->name);

			if (cdf_write_layer(cdf, blay)) {
				if (typeInfo->write(cdf, layer->data, totelem)) {
					/* pass */
				}
				else {
					break;
				}
			}
			else {
				break;
			}
		}
	}

	if (i != data->totlayer) {
		fprintf(stderr, "Failed to write data to %s.\n", filename);
		cdf_free(cdf);
		return;
	}

	for (i = 0; i < data->totlayer; i++) {
		layer = &data->layers[i];
		typeInfo = layerType_getInfo(layer->type);

		if ((layer->flag & CD_FLAG_EXTERNAL) && typeInfo->write) {
			if (free) {
				if (typeInfo->free)
					typeInfo->free(layer->data, totelem, typeInfo->size);
				layer->flag &= ~CD_FLAG_IN_MEMORY;
			}
		}
	}

	cdf_write_close(cdf);
	cdf_free(cdf);
}

void CustomData_external_add(CustomData *data, ID *UNUSED(id), int type, int UNUSED(totelem), const char *filename)
{
	CustomDataExternal *external = data->external;
	CustomDataLayer *layer;
	int layer_index;

	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return;

	layer = &data->layers[layer_index];

	if (layer->flag & CD_FLAG_EXTERNAL)
		return;

	if (!external) {
		external = MEM_callocN(sizeof(CustomDataExternal), "CustomDataExternal");
		data->external = external;
	}
	BLI_strncpy(external->filename, filename, sizeof(external->filename));

	layer->flag |= CD_FLAG_EXTERNAL | CD_FLAG_IN_MEMORY;
}

void CustomData_external_remove(CustomData *data, ID *id, int type, int totelem)
{
	CustomDataExternal *external = data->external;
	CustomDataLayer *layer;
	//char filename[FILE_MAX];
	int layer_index; // i, remove_file;

	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return;

	layer = &data->layers[layer_index];

	if (!external)
		return;

	if (layer->flag & CD_FLAG_EXTERNAL) {
		if (!(layer->flag & CD_FLAG_IN_MEMORY))
			CustomData_external_read(data, id, CD_TYPE_AS_MASK(layer->type), totelem);

		layer->flag &= ~CD_FLAG_EXTERNAL;

#if 0
		remove_file = 1;
		for (i = 0; i < data->totlayer; i++)
			if (data->layers[i].flag & CD_FLAG_EXTERNAL)
				remove_file = 0;

		if (remove_file) {
			customdata_external_filename(filename, id, external);
			cdf_remove(filename);
			CustomData_external_free(data);
		}
#endif
	}
}

bool CustomData_external_test(CustomData *data, int type)
{
	CustomDataLayer *layer;
	int layer_index;

	layer_index = CustomData_get_active_layer_index(data, type);
	if (layer_index == -1) return false;

	layer = &data->layers[layer_index];
	return (layer->flag & CD_FLAG_EXTERNAL) != 0;
}

#if 0
void CustomData_external_remove_object(CustomData *data, ID *id)
{
	CustomDataExternal *external = data->external;
	char filename[FILE_MAX];

	if (!external)
		return;

	customdata_external_filename(filename, id, external);
	cdf_remove(filename);
	CustomData_external_free(data);
}
#endif

/* ********** Mesh-to-mesh data transfer ********** */
static void copy_bit_flag(void *dst, const void *src, const size_t data_size, const uint64_t flag)
{
#define COPY_BIT_FLAG(_type, _dst, _src, _f)                    \
{                                                               \
	const _type _val = *((_type *)(_src)) & ((_type)(_f));      \
	*((_type *)(_dst)) &= ~((_type)(_f));                       \
	*((_type *)(_dst)) |= _val;                                 \
} (void) 0

	switch (data_size) {
		case 1:
			COPY_BIT_FLAG(uint8_t, dst, src, flag);
			break;
		case 2:
			COPY_BIT_FLAG(uint16_t, dst, src, flag);
			break;
		case 4:
			COPY_BIT_FLAG(uint32_t, dst, src, flag);
			break;
		case 8:
			COPY_BIT_FLAG(uint64_t, dst, src, flag);
			break;
		default:
			//printf("ERROR %s: Unknown flags-container size (%zu)\n", __func__, datasize);
			break;
	}

#undef COPY_BIT_FLAG
}

static bool check_bit_flag(const void *data, const size_t data_size, const uint64_t flag)
{
	switch (data_size) {
		case 1:
			return ((*((uint8_t *)data) & ((uint8_t)flag)) != 0);
		case 2:
			return ((*((uint16_t *)data) & ((uint16_t)flag)) != 0);
		case 4:
			return ((*((uint32_t *)data) & ((uint32_t)flag)) != 0);
		case 8:
			return ((*((uint64_t *)data) & ((uint64_t)flag)) != 0);
		default:
			//printf("ERROR %s: Unknown flags-container size (%zu)\n", __func__, datasize);
			return false;
	}
}

static void customdata_data_transfer_interp_generic(
        const CustomDataTransferLayerMap *laymap, void *data_dst,
        const void **sources, const float *weights, const int count,
        const float mix_factor)
{
	/* Fake interpolation, we actually copy highest weighted source to dest.
	 * Note we also handle bitflags here, in which case we rather choose to transfer value of elements totaling
	 * more than 0.5 of weight. */

	int best_src_idx = 0;

	const int data_type = laymap->data_type;
	const int mix_mode = laymap->mix_mode;

	size_t data_size;
	const uint64_t data_flag = laymap->data_flag;

	cd_interp interp_cd = NULL;
	cd_copy copy_cd = NULL;

	void *tmp_dst;

	if (!sources) {
		/* Not supported here, abort. */
		return;
	}

	if (data_type & CD_FAKE) {
		data_size = laymap->data_size;
	}
	else {
		const LayerTypeInfo *type_info = layerType_getInfo(data_type);

		data_size = (size_t)type_info->size;
		interp_cd = type_info->interp;
		copy_cd = type_info->copy;
	}

	tmp_dst = MEM_mallocN(data_size, __func__);

	if (count > 1 && !interp_cd) {
		int i;

		if (data_flag) {
			/* Boolean case, we can 'interpolate' in two groups, and choose value from highest weighted group. */
			float tot_weight_true = 0.0f;
			int item_true_idx = -1, item_false_idx = -1;

			for (i = 0; i < count; i++) {
				if (check_bit_flag(sources[i], data_size, data_flag)) {
					tot_weight_true += weights[i];
					item_true_idx = i;
				}
				else {
					item_false_idx = i;
				}
			}
			best_src_idx = (tot_weight_true >= 0.5f) ? item_true_idx : item_false_idx;
		}
		else {
			/* We just choose highest weighted source. */
			float max_weight = 0.0f;

			for (i = 0; i < count; i++) {
				if (weights[i] > max_weight) {
					max_weight = weights[i];
					best_src_idx = i;
				}
			}
		}
	}

	BLI_assert(best_src_idx >= 0);

	if (interp_cd) {
		interp_cd(sources, weights, NULL, count, tmp_dst);
	}
	else if (data_flag) {
		copy_bit_flag(tmp_dst, sources[best_src_idx], data_size, data_flag);
	}
	/* No interpolation, just copy highest weight source element's data. */
	else if (copy_cd) {
		copy_cd(sources[best_src_idx], tmp_dst, 1);
	}
	else {
		memcpy(tmp_dst, sources[best_src_idx], data_size);
	}

	if (data_flag) {
		/* Bool flags, only copy if dest data is set (resp. unset) - only 'advanced' modes we can support here! */
		if (mix_factor >= 0.5f &&
		    ((mix_mode == CDT_MIX_TRANSFER) ||
		     (mix_mode == CDT_MIX_REPLACE_ABOVE_THRESHOLD && check_bit_flag(data_dst, data_size, data_flag)) ||
		     (mix_mode == CDT_MIX_REPLACE_BELOW_THRESHOLD && !check_bit_flag(data_dst, data_size, data_flag))))
		{
			copy_bit_flag(data_dst, tmp_dst, data_size, data_flag);
		}
	}
	else if (!(data_type & CD_FAKE)) {
		CustomData_data_mix_value(data_type, tmp_dst, data_dst, mix_mode, mix_factor);
	}
	/* Else we can do nothing by default, needs custom interp func!
	 * Note this is here only for sake of consistency, not expected to be used much actually? */
	else {
		if (mix_factor >= 0.5f) {
			memcpy(data_dst, tmp_dst, data_size);
		}
	}

	MEM_freeN(tmp_dst);
}

void CustomData_data_transfer(const MeshPairRemap *me_remap, const CustomDataTransferLayerMap *laymap)
{
	MeshPairRemapItem *mapit = me_remap->items;
	const int totelem = me_remap->items_num;
	int i;

	const int data_type = laymap->data_type;
	const void *data_src = laymap->data_src;
	void *data_dst = laymap->data_dst;

	size_t data_step;
	size_t data_size;
	size_t data_offset;

	cd_datatransfer_interp interp = NULL;

	size_t tmp_buff_size = 32;
	const void **tmp_data_src = NULL;

	/* Note: NULL data_src may happen and be valid (see vgroups...). */
	if (!data_dst) {
		return;
	}

	if (data_src) {
		tmp_data_src = MEM_mallocN(sizeof(*tmp_data_src) * tmp_buff_size, __func__);
	}

	if (data_type & CD_FAKE) {
		data_step = laymap->elem_size;
		data_size = laymap->data_size;
		data_offset = laymap->data_offset;
	}
	else {
		const LayerTypeInfo *type_info = layerType_getInfo(data_type);

		/* Note: we can use 'fake' CDLayers, like e.g. for crease, bweight, etc. :/ */
		data_size = (size_t)type_info->size;
		data_step = laymap->elem_size ? laymap->elem_size : data_size;
		data_offset = laymap->data_offset;
	}

	interp = laymap->interp ? laymap->interp : customdata_data_transfer_interp_generic;

	for (i = 0; i < totelem; i++, data_dst = POINTER_OFFSET(data_dst, data_step), mapit++) {
		const int sources_num = mapit->sources_num;
		const float mix_factor = laymap->mix_weights ? laymap->mix_weights[i] : laymap->mix_factor;
		int j;

		if (!sources_num) {
			/* No sources for this element, skip it. */
			continue;
		}

		if (tmp_data_src) {
			if (UNLIKELY(sources_num > tmp_buff_size)) {
				tmp_buff_size = (size_t)sources_num;
				tmp_data_src = MEM_reallocN((void *)tmp_data_src, sizeof(*tmp_data_src) * tmp_buff_size);
			}

			for (j = 0; j < sources_num; j++) {
				const size_t src_idx = (size_t)mapit->indices_src[j];
				tmp_data_src[j] = POINTER_OFFSET(data_src, (data_step * src_idx) + data_offset);
			}
		}

		interp(laymap, POINTER_OFFSET(data_dst, data_offset), tmp_data_src, mapit->weights_src, sources_num, mix_factor);
	}

	MEM_SAFE_FREE(tmp_data_src);
}