Transfer Data: add main core code and operators.

This add code needed to map a CD data layout from source mesh towards destination one,
and code needed to actually transfer data, using BKE's mesh remap generated data.

This allows to transfer most CD layers (vgroups, vcols, uvs...) as well as fake, boolean ones
(like smooth/sharp edges/faces, etc.). Some types are not yet transferable, mainly
shape keys, this is known TODO.

Data transfer can also use some advanced mixing in some cases (mostly, vgroups and vcols).

Notes:
* New transfer operators transfer data from active object towards selected ones.
* Modifier will be committed separately.
* Old weight transfer code (for vgroups) is kept for now, mostly because it is the only
  usable one in weightpaint mode (it transfers from selected object to active one,
  this is not sensible in Object mode, but needed in WeightPaint one). This will be addressed soon.

Again, heavily reviewed and enhanced by Campbell, thanks!

9 files changed, 2266 insertions, 16 deletions

diff --git a/source/blender/blenkernel/BKE_customdata.h b/source/blender/blenkernel/BKE_customdata.h
index 30a58891bda..08edde1cec0 100644
--- a/source/blender/blenkernel/BKE_customdata.h
+++ b/source/blender/blenkernel/BKE_customdata.h
@@ -41,6 +41,8 @@ extern "C" {
 #include "BLI_sys_types.h"
 #include "BLI_utildefines.h"
 
+#include "DNA_customdata_types.h"
+
 struct BMesh;
 struct ID;
 struct CustomData;
@@ -77,6 +79,9 @@ extern const CustomDataMask CD_MASK_EVERYTHING;
 
 void customData_mask_layers__print(CustomDataMask mask);
 
+typedef void (*cd_interp)(void **sources, const float *weights, const float *sub_weights, int count, void *dest);
+typedef void (*cd_copy)(const void *source, void *dest, int count);
+
 /**
  * Checks if the layer at physical offset \a layer_n (in data->layers) support math
  * the below operations.
@@ -96,6 +101,9 @@ bool CustomData_bmesh_has_free(const struct CustomData *data);
  * implemented for mloopuv/mloopcol, for now.*/
 void CustomData_data_copy_value(int type, const void *source, void *dest);
 
+/* Same as above, but doing advanced mixing. Only available for a few types of data (like colors...). */
+void CustomData_data_mix_value(int type, const void *source, void *dest, const int mixmode, const float mixfactor);
+
 /* compares if data1 is equal to data2.  type is a valid CustomData type
  * enum (e.g. CD_MLOOPUV). the layer type's equal function is used to compare
  * the data, if it exists, otherwise memcmp is used.*/
@@ -246,14 +254,14 @@ void *CustomData_bmesh_get_n(const struct CustomData *data, void *block, int typ
 void *CustomData_bmesh_get_layer_n(const struct CustomData *data, void *block, int n);
 
 bool CustomData_set_layer_name(const struct CustomData *data, int type, int n, const char *name);
+const char *CustomData_get_layer_name(const struct CustomData *data, int type, int n);
 
 /* gets a pointer to the active or first layer of type
  * returns NULL if there is no layer of type
  */
 void *CustomData_get_layer(const struct CustomData *data, int type);
 void *CustomData_get_layer_n(const struct CustomData *data, int type, int n);
-void *CustomData_get_layer_named(const struct CustomData *data, int type,
-                                 const char *name);
+void *CustomData_get_layer_named(const struct CustomData *data, int type, const char *name);
 int CustomData_get_offset(const struct CustomData *data, int type);
 int CustomData_get_n_offset(const struct CustomData *data, int type, int n);
 
@@ -362,6 +370,82 @@ void CustomData_external_read(struct CustomData *data,
 void CustomData_external_reload(struct CustomData *data,
                                 struct ID *id, CustomDataMask mask, int totelem);
 
+/* Mesh-to-mesh transfer data. */
+
+struct MeshPairRemap;
+typedef struct CustomDataTransferLayerMap CustomDataTransferLayerMap;
+
+typedef void (*cd_datatransfer_interp)(
+        const CustomDataTransferLayerMap *laymap, void *dest,
+        void **sources, const float *weights, const int count, const float mix_factor);
+
+/**
+ * Fake CD_LAYERS (those are actually 'real' data stored directly into elements' structs, or otherwise not (directly)
+ * accessible to usual CDLayer system). */
+enum {
+	CD_FAKE             = 1 << 8,
+
+	/* Vertices. */
+	CD_FAKE_MDEFORMVERT = CD_FAKE | CD_MDEFORMVERT,  /* *sigh* due to how vgroups are stored :( . */
+	CD_FAKE_SHAPEKEY    = CD_FAKE | CD_SHAPEKEY,  /* Not available as real CD layer in non-bmesh context. */
+
+	/* Edges. */
+	CD_FAKE_SEAM        = CD_FAKE | 100,  /* UV seam flag for edges. */
+	CD_FAKE_CREASE      = CD_FAKE | CD_CREASE,  /* *sigh*. */
+
+	/* Multiple types of mesh elements... */
+	CD_FAKE_BWEIGHT     = CD_FAKE | CD_BWEIGHT,  /* *sigh*. */
+	CD_FAKE_UV          = CD_FAKE | CD_MLOOPUV,  /* UV flag, because we handle both loop's UVs and poly's textures. */
+
+	CD_FAKE_SHARP       = CD_FAKE | 200,  /* Sharp flag for edges, smooth flag for faces. */
+};
+
+enum {
+	ME_VERT = 1 << 0,
+	ME_EDGE = 1 << 1,
+	ME_POLY = 1 << 2,
+	ME_LOOP = 1 << 3,
+};
+
+/**
+ * How to filter out some elements (to leave untouched).
+ * Note those options are highly dependent on type of transferred data! */
+enum {
+	CDT_MIX_NOMIX                   = -1,  /* Special case, only used because we abuse 'copy' CD callback. */
+	CDT_MIX_TRANSFER                = 0,
+	CDT_MIX_REPLACE_ABOVE_THRESHOLD = 1,
+	CDT_MIX_REPLACE_BELOW_THRESHOLD = 2,
+	CDT_MIX_MIX                     = 16,
+	CDT_MIX_ADD                     = 17,
+	CDT_MIX_SUB                     = 18,
+	CDT_MIX_MUL                     = 19,
+	/* etc. etc. */
+};
+
+typedef struct CustomDataTransferLayerMap {
+	CustomDataTransferLayerMap *next, *prev;
+
+	int data_type;
+	int mix_mode;
+	float mix_factor;
+	const float *mix_weights;  /* If non-NULL, array of weights, one for each dest item, replaces mix_factor. */
+
+	void *data_src;      /* Data source array (can be regular CD data, vertices/edges/etc., keyblocks...). */
+	void *data_dst;      /* Data dest array (same type as dat_src). */
+	int   data_src_n;    /* Index to affect in data_src (used e.g. for vgroups). */
+	int   data_dst_n;    /* Index to affect in data_dst (used e.g. for vgroups). */
+	size_t elem_size;    /* Size of one element of data_src/data_dst. */
+
+	size_t data_size;    /* Size of actual data we transfer. */
+	size_t data_offset;  /* Offset of actual data we transfer (in element contained in data_src/dst). */
+	uint64_t data_flag;  /* For bitflag transfer, flag(s) to affect in transfered data. */
+
+	cd_datatransfer_interp interp;
+} CustomDataTransferLayerMap;
+
+/* Those functions assume src_n and dst_n layers of given type exist in resp. src and dst. */
+void CustomData_data_transfer(const struct MeshPairRemap *me_remap, const CustomDataTransferLayerMap *laymap);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/blender/blenkernel/BKE_deform.h b/source/blender/blenkernel/BKE_deform.h
index e203549fef5..08312035e40 100644
--- a/source/blender/blenkernel/BKE_deform.h
+++ b/source/blender/blenkernel/BKE_deform.h
@@ -39,6 +39,10 @@ struct Object;
 struct ListBase;
 struct bDeformGroup;
 struct MDeformVert;
+struct MVert;
+struct MEdge;
+struct MLoop;
+struct MPoly;
 
 struct bDeformGroup *BKE_defgroup_new(struct Object *ob, const char *name);
 void                 defgroup_copy_list(struct ListBase *lb1, struct ListBase *lb2);
@@ -85,6 +89,19 @@ void defvert_normalize_lock_map(struct MDeformVert *dvert,
                                 const bool *vgroup_subset, const int vgroup_tot,
                                 const bool *lock_flags, const int defbase_tot);
 
+/* Utilities to 'extract' a given vgroup into a simple float array, for verts, but also edges/polys/loops. */
+void BKE_defvert_extract_vgroup_to_vertweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_edgeweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MEdge *edges, const int num_edges,
+        float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_loopweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MLoop *loops, const int num_loops,
+        float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_polyweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MLoop *loops, const int num_loops,
+        struct MPoly *polys, const int num_polys, float *r_weights, const bool invert_vgroup);
+
 /* utility function, note that MAX_VGROUP_NAME chars is the maximum string length since its only
  * used with defgroups currently */
 
diff --git a/source/blender/blenkernel/BKE_object_data_transfer.h b/source/blender/blenkernel/BKE_object_data_transfer.h
new file mode 100644
index 00000000000..fe218901201
--- /dev/null
+++ b/source/blender/blenkernel/BKE_object_data_transfer.h
@@ -0,0 +1,158 @@
+/*
+ * ***** 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) 2014 Blender Foundation.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Bastien Montagne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/BKE_object_data_transfer.h
+ *  \ingroup bke
+ */
+
+#ifndef __BKE_OBJECT_DATA_TRANSFER_H__
+#define __BKE_OBJECT_DATA_TRANSFER_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "BKE_customdata.h"
+
+struct Object;
+struct Scene;
+struct SpaceTransform;
+struct ReportList;
+
+/* Warning, those def are stored in files (TransferData modifier), *DO NOT* modify those values. */
+enum {
+	DT_TYPE_MDEFORMVERT             = 1 << 0,
+	DT_TYPE_SHAPEKEY                = 1 << 1,
+	DT_TYPE_SKIN                    = 1 << 2,
+	DT_TYPE_BWEIGHT_VERT            = 1 << 3,
+
+	DT_TYPE_SHARP_EDGE              = 1 << 8,
+	DT_TYPE_SEAM                    = 1 << 9,
+	DT_TYPE_CREASE                  = 1 << 10,
+	DT_TYPE_BWEIGHT_EDGE            = 1 << 11,
+	DT_TYPE_FREESTYLE_EDGE          = 1 << 12,
+
+	DT_TYPE_VCOL                    = 1 << 16,
+
+	DT_TYPE_UV                      = 1 << 24,
+	DT_TYPE_SHARP_FACE              = 1 << 25,
+	DT_TYPE_FREESTYLE_FACE          = 1 << 26,
+#define \
+	DT_TYPE_MAX                            27
+
+	DT_TYPE_VERT_ALL                = DT_TYPE_MDEFORMVERT | DT_TYPE_SHAPEKEY | DT_TYPE_SKIN | DT_TYPE_BWEIGHT_VERT,
+	DT_TYPE_EDGE_ALL                = DT_TYPE_SHARP_EDGE | DT_TYPE_SEAM | DT_TYPE_CREASE | DT_TYPE_BWEIGHT_EDGE |
+	                                  DT_TYPE_FREESTYLE_EDGE,
+	DT_TYPE_LOOP_ALL                = DT_TYPE_VCOL | DT_TYPE_UV,
+	DT_TYPE_POLY_ALL                = DT_TYPE_UV | DT_TYPE_SHARP_FACE | DT_TYPE_FREESTYLE_FACE,
+};
+
+
+CustomDataMask BKE_object_data_transfer_dttypes_to_cdmask(const int dtdata_types);
+bool BKE_object_data_transfer_get_dttypes_capacity(
+        const int dtdata_types, bool *r_advanced_mixing, bool *r_threshold);
+int BKE_object_data_transfer_get_dttypes_item_types(const int dtdata_types);
+
+int BKE_object_data_transfer_dttype_to_cdtype(const int dtdata_type);
+int BKE_object_data_transfer_dttype_to_srcdst_index(const int dtdata_type);
+
+#define DT_DATATYPE_IS_VERT(_dt) \
+	ELEM(_dt, DT_TYPE_MDEFORMVERT, DT_TYPE_SHAPEKEY, DT_TYPE_SKIN, DT_TYPE_BWEIGHT_VERT)
+#define DT_DATATYPE_IS_EDGE(_dt) \
+	ELEM(_dt, DT_TYPE_CREASE, DT_TYPE_SHARP_EDGE, DT_TYPE_SEAM, DT_TYPE_BWEIGHT_EDGE, DT_TYPE_FREESTYLE_EDGE)
+#define DT_DATATYPE_IS_LOOP(_dt) \
+	ELEM(_dt, DT_TYPE_UV, DT_TYPE_VCOL)
+#define DT_DATATYPE_IS_POLY(_dt) \
+	ELEM(_dt, DT_TYPE_UV, DT_TYPE_SHARP_FACE, DT_TYPE_FREESTYLE_FACE)
+
+#define DT_DATATYPE_IS_MULTILAYERS(_dt) \
+	ELEM(_dt, DT_TYPE_MDEFORMVERT, DT_TYPE_SHAPEKEY, DT_TYPE_VCOL, DT_TYPE_UV)
+
+
+enum {
+	DT_MULTILAYER_INDEX_INVALID         = -1,
+	DT_MULTILAYER_INDEX_MDEFORMVERT     = 0,
+	DT_MULTILAYER_INDEX_SHAPEKEY        = 1,
+	DT_MULTILAYER_INDEX_VCOL            = 2,
+	DT_MULTILAYER_INDEX_UV              = 3,
+	DT_MULTILAYER_INDEX_MAX             = 4,
+};
+
+/* Below we keep positive values for real layers idx (generated dynamically). */
+
+/* How to select data layers, for types supporting multi-layers.
+ * Here too, some options are highly dependent on type of transferred data! */
+enum {
+	DT_LAYERS_ACTIVE_SRC                 = -1,
+	DT_LAYERS_ALL_SRC                    = -2,
+	/* Datatype-specific. */
+	DT_LAYERS_VGROUP_SRC                 = 1 << 8,
+	DT_LAYERS_VGROUP_SRC_BONE_SELECT     = -(DT_LAYERS_VGROUP_SRC | 1),
+	DT_LAYERS_VGROUP_SRC_BONE_DEFORM     = -(DT_LAYERS_VGROUP_SRC | 2),
+	/* Other types-related modes... */
+};
+
+/* How to map a source layer to a destination layer, for types supporting multi-layers.
+ * Note: if no matching layer can be found, it will be created. */
+enum {
+	DT_LAYERS_ACTIVE_DST                 = -1,  /* Only for DT_LAYERS_FROMSEL_ACTIVE. */
+	DT_LAYERS_NAME_DST                   = -2,
+	DT_LAYERS_INDEX_DST                  = -3,
+#if 0  /* TODO */
+	DT_LAYERS_CREATE_DST                 = -4,  /* Never replace existing data in dst, always create new layers. */
+#endif
+};
+
+void BKE_object_data_transfer_layout(
+        struct Scene *scene, struct Object *ob_src, struct Object *ob_dst, const int data_types, const bool use_delete,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX]);
+
+bool BKE_object_data_transfer_mesh(
+        struct Scene *scene,
+        struct Object *ob_src, struct Object *ob_dst, const int data_types, bool use_create,
+        const int map_vert_mode, const int map_edge_mode, const int map_loop_mode, const int map_poly_mode,
+        struct SpaceTransform *space_transform, const float max_distance, const float ray_radius,
+        const float islands_handling_precision,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX],
+        const int mix_mode, const float mix_factor, const char *vgroup_name, const bool invert_vgroup,
+        struct ReportList *reports);
+bool BKE_object_data_transfer_dm(
+        struct Scene *scene,
+        struct Object *ob_src, struct Object *ob_dst, struct DerivedMesh *dm_dst,
+        const int data_types, bool use_create,
+        const int map_vert_mode, const int map_edge_mode, const int map_loop_mode, const int map_poly_mode,
+        struct SpaceTransform *space_transform, const float max_distance, const float ray_radius,
+        const float islands_handling_precision,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX],
+        const int mix_mode, const float mix_factor, const char *vgroup_name, const bool invert_vgroup,
+        struct ReportList *reports);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* __BKE_OBJECT_DATA_TRANSFER_H__ */
diff --git a/source/blender/blenkernel/BKE_object_deform.h b/source/blender/blenkernel/BKE_object_deform.h
index 0e5ad2d51c8..e956815d6f7 100644
--- a/source/blender/blenkernel/BKE_object_deform.h
+++ b/source/blender/blenkernel/BKE_object_deform.h
@@ -72,4 +72,11 @@ bool *BKE_object_defgroup_selected_get(struct Object *ob, int defbase_tot, int *
 }
 #endif
 
+/* Select helpers */
+bool *BKE_objdef_vgroup_subset_from_select_type(
+        struct Object *ob, enum eVGroupSelect subset_type, int *r_vgroup_tot, int *r_subset_count);
+void BKE_objdef_vgroup_subset_to_index_array(
+        const bool *vgroup_validmap, const int vgroup_tot, int *r_vgroup_subset_map);
+
+
 #endif  /* __BKE_OBJECT_DEFORM_H__ */
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 5976e041703..31e28f9e51b 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -130,6 +130,7 @@ set(SRC
 	intern/nla.c
 	intern/node.c
 	intern/object.c
+	intern/object_data_transfer.c
 	intern/object_deform.c
 	intern/object_dupli.c
 	intern/ocean.c
@@ -238,6 +239,7 @@ set(SRC
 	BKE_nla.h
 	BKE_node.h
 	BKE_object.h
+	BKE_object_data_transfer.h
 	BKE_object_deform.h
 	BKE_ocean.h
 	BKE_packedFile.h
@@ -277,6 +279,7 @@ set(SRC
 	tracking_private.h
 	intern/CCGSubSurf.h
 	intern/pbvh_intern.h
+	intern/data_transfer_intern.h
 )
 
 if(WITH_BINRELOC)
diff --git a/source/blender/blenkernel/intern/customdata.c b/source/blender/blenkernel/intern/customdata.c
index 5e86ca596cf..856f893e876 100644
--- a/source/blender/blenkernel/intern/customdata.c
+++ b/source/blender/blenkernel/intern/customdata.c
@@ -48,6 +48,7 @@
 #include "BLI_string.h"
 #include "BLI_path_util.h"
 #include "BLI_math.h"
+#include "BLI_math_color_blend.h"
 #include "BLI_mempool.h"
 
 #include "BLF_translation.h"
@@ -56,6 +57,8 @@
 #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"
@@ -92,7 +95,7 @@ typedef struct LayerTypeInfo {
 	 * (deep copy if appropriate)
 	 * if NULL, memcpy is used
 	 */
-	void (*copy)(const void *source, void *dest, int count);
+	cd_copy copy;
 
 	/**
 	 * a function to free any dynamically allocated components of this
@@ -117,8 +120,7 @@ typedef struct LayerTypeInfo {
 	 *       applying changes while reading from sources.
 	 *       See bug [#32395] - Campbell.
 	 */
-	void (*interp)(void **sources, const float *weights, const float *sub_weights,
-	               int count, void *dest);
+	cd_interp interp;
 
 	/** a function to swap the data in corners of the element */
 	void (*swap)(void *data, const int *corner_indices);
@@ -134,7 +136,7 @@ typedef struct LayerTypeInfo {
 	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);
+	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);
@@ -620,14 +622,53 @@ static void layerFree_grid_paint_mask(void *data, int count, int UNUSED(size))
 }
 
 /* --------- */
-static void layerCopyValue_mloopcol(const void *source, void *dest)
+static void layerCopyValue_mloopcol(const void *source, void *dest, const int mixmode, const float mixfactor)
 {
 	const MLoopCol *m1 = source;
 	MLoopCol *m2 = dest;
-	
-	m2->r = m1->r;
-	m2->g = m1->g;
-	m2->b = m1->b;
+	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;
 }
 
@@ -758,12 +799,19 @@ static int layerMaxNum_mloopcol(void)
 	return MAX_MCOL;
 }
 
-static void layerCopyValue_mloopuv(const void *source, void *dest)
+static void layerCopyValue_mloopuv(const void *source, void *dest, const int mixmode, const float mixfactor)
 {
 	const MLoopUV *luv1 = source;
 	MLoopUV *luv2 = dest;
 
-	copy_v2_v2(luv2->uv, luv1->uv);
+	/* 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)
@@ -833,7 +881,8 @@ static void layerInterp_mloopuv(void **sources, const float *weights,
 }
 
 /* origspace is almost exact copy of mloopuv's, keep in sync */
-static void layerCopyValue_mloop_origspace(const void *source, void *dest)
+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;
@@ -2261,7 +2310,7 @@ int CustomData_get_n_offset(const CustomData *data, int type, int n)
 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 */
-	int layer_index = CustomData_get_layer_index_n(data, type, n);
+	const int layer_index = CustomData_get_layer_index_n(data, type, n);
 
 	if ((layer_index == -1) || !name)
 		return false;
@@ -2271,6 +2320,13 @@ bool CustomData_set_layer_name(const CustomData *data, int type, int n, const ch
 	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 */
@@ -2764,11 +2820,28 @@ void CustomData_data_copy_value(int type, const void *source, void *dest)
 	if (!dest) return;
 
 	if (typeInfo->copyvalue)
-		typeInfo->copyvalue(source, dest);
+		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);
@@ -3464,3 +3537,233 @@ void CustomData_external_remove_object(CustomData *data, ID *id)
 }
 #endif
 
+/* ********** Mesh-to-mesh data transfer ********** */
+static void copy_bit_flag(void *dst, 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(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, 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 totalizing
+	 * 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, (char *)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((char *)sources[best_src_idx], (char *)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;
+	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;
+	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 = (char *)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(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] = (char *)data_src + data_step * src_idx + data_offset;
+			}
+		}
+
+		interp(laymap, (char *)data_dst + data_offset, tmp_data_src, mapit->weights_src, sources_num, mix_factor);
+	}
+
+	MEM_SAFE_FREE(tmp_data_src);
+}
diff --git a/source/blender/blenkernel/intern/data_transfer_intern.h b/source/blender/blenkernel/intern/data_transfer_intern.h
new file mode 100644
index 00000000000..913325afce0
--- /dev/null
+++ b/source/blender/blenkernel/intern/data_transfer_intern.h
@@ -0,0 +1,60 @@
+/*
+ * ***** 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) 2014 Blender Foundation.
+ * All rights reserved.
+ *
+ * 
+ * Contributor(s): Bastien Montagne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/data_transfer_intern.h
+ *  \ingroup bke
+ */
+
+#ifndef __DATA_TRANSFER_INTERN_H__
+#define __DATA_TRANSFER_INTERN_H__
+
+struct CustomDataTransferLayerMap;
+struct CustomData;
+struct ListBase;
+
+float data_transfer_interp_float_do(
+        const int mix_mode, const float val_dst, const float val_src, const float mix_factor);
+
+/* Copied from BKE_customdata.h :( */
+typedef void (*cd_datatransfer_interp)(const struct CustomDataTransferLayerMap *laymap, void *dest,
+                                       void **sources, const float *weights, const int count, const float mix_factor);
+
+void data_transfer_layersmapping_add_item(
+        struct ListBase *r_map, const int data_type, const int mix_mode,
+        const float mix_factor, const float *mix_weights,
+        void *data_src, void *data_dst, const int data_src_n, const int data_dst_n,
+        const size_t elem_size, const size_t data_size, const size_t data_offset, const uint64_t data_flag,
+        cd_datatransfer_interp interp);
+
+/* Type-specific. */
+
+bool data_transfer_layersmapping_vgroups(
+        struct ListBase *r_map, const int mix_mode, const float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete,
+        struct Object *ob_src, struct Object *ob_dst, struct CustomData *cd_src, struct CustomData *cd_dst,
+        const bool use_dupref_dst, const int fromlayers, const int tolayers);
+
+#endif  /* __DATA_TRANSFER_INTERN_H__ */
diff --git a/source/blender/blenkernel/intern/deform.c b/source/blender/blenkernel/intern/deform.c
index d3148dbc8e9..4ed9278ab26 100644
--- a/source/blender/blenkernel/intern/deform.c
+++ b/source/blender/blenkernel/intern/deform.c
@@ -39,7 +39,9 @@
 #include "MEM_guardedalloc.h"
 
 #include "DNA_meshdata_types.h"
+#include "DNA_mesh_types.h"
 #include "DNA_object_types.h"
+#include "DNA_scene_types.h"
 
 #include "BLI_listbase.h"
 #include "BLI_math.h"
@@ -49,7 +51,14 @@
 
 #include "BLF_translation.h"
 
+#include "BKE_customdata.h"
+#include "BKE_object_data_transfer.h"
 #include "BKE_deform.h"  /* own include */
+#include "BKE_mesh_mapping.h"
+#include "BKE_object_deform.h"
+
+#include "data_transfer_intern.h"
+
 
 bDeformGroup *BKE_defgroup_new(Object *ob, const char *name)
 {
@@ -960,3 +969,385 @@ void BKE_defvert_array_free(MDeformVert *dvert, int totvert)
 
 	MEM_freeN(dvert);
 }
+
+void BKE_defvert_extract_vgroup_to_vertweights(
+        MDeformVert *dvert, const int defgroup, const int num_verts, float *r_weights, const bool invert_vgroup)
+{
+	if (dvert && defgroup != -1) {
+		int i = num_verts;
+
+		while (i--) {
+			const float w = defvert_find_weight(&dvert[i], defgroup);
+			r_weights[i] = invert_vgroup ? (1.0f - w) : w;
+		}
+	}
+	else {
+		fill_vn_fl(r_weights, invert_vgroup ? 1.0f : 0.0f, num_verts);
+	}
+}
+
+/* The following three make basic interpolation, using temp vert_weights array to avoid looking up same weight
+ * several times. */
+
+void BKE_defvert_extract_vgroup_to_edgeweights(
+        MDeformVert *dvert, const int defgroup, const int num_verts, MEdge *edges, const int num_edges,
+        float *r_weights, const bool invert_vgroup)
+{
+	if (dvert && defgroup != -1) {
+		int i = num_edges;
+		float *tmp_weights = MEM_mallocN(sizeof(*tmp_weights) * (size_t)num_verts, __func__);
+
+		BKE_defvert_extract_vgroup_to_vertweights(dvert, defgroup, num_verts, tmp_weights, invert_vgroup);
+
+		while (i--) {
+			MEdge *me = &edges[i];
+
+			r_weights[i] = (tmp_weights[me->v1] + tmp_weights[me->v2]) * 0.5f;
+		}
+
+		MEM_freeN(tmp_weights);
+	}
+	else {
+		fill_vn_fl(r_weights, 0.0f, num_edges);
+	}
+}
+
+void BKE_defvert_extract_vgroup_to_loopweights(
+        MDeformVert *dvert, const int defgroup, const int num_verts, MLoop *loops, const int num_loops,
+        float *r_weights, const bool invert_vgroup)
+{
+	if (dvert && defgroup != -1) {
+		int i = num_loops;
+		float *tmp_weights = MEM_mallocN(sizeof(*tmp_weights) * (size_t)num_verts, __func__);
+
+		BKE_defvert_extract_vgroup_to_vertweights(dvert, defgroup, num_verts, tmp_weights, invert_vgroup);
+
+		while (i--) {
+			MLoop *ml = &loops[i];
+
+			r_weights[i] = tmp_weights[ml->v];
+		}
+
+		MEM_freeN(tmp_weights);
+	}
+	else {
+		fill_vn_fl(r_weights, 0.0f, num_loops);
+	}
+}
+
+void BKE_defvert_extract_vgroup_to_polyweights(
+        MDeformVert *dvert, const int defgroup, const int num_verts, MLoop *loops, const int UNUSED(num_loops),
+        MPoly *polys, const int num_polys, float *r_weights, const bool invert_vgroup)
+{
+	if (dvert && defgroup != -1) {
+		int i = num_polys;
+		float *tmp_weights = MEM_mallocN(sizeof(*tmp_weights) * (size_t)num_verts, __func__);
+
+		BKE_defvert_extract_vgroup_to_vertweights(dvert, defgroup, num_verts, tmp_weights, invert_vgroup);
+
+		while (i--) {
+			MPoly *mp = &polys[i];
+			MLoop *ml = &loops[mp->loopstart];
+			int j = mp->totloop;
+			float w = 0.0f;
+
+			for (; j--; ml++) {
+				w += tmp_weights[ml->v];
+			}
+			r_weights[i] = w / (float)mp->totloop;
+		}
+
+		MEM_freeN(tmp_weights);
+	}
+	else {
+		fill_vn_fl(r_weights, 0.0f, num_polys);
+	}
+}
+
+/*********** Data Transfer **********/
+
+static void vgroups_datatransfer_interp(const CustomDataTransferLayerMap *laymap, void *dest,
+                                        void **sources, const float *weights, const int count, const float mix_factor)
+{
+	MDeformVert **data_src = (MDeformVert **)sources;
+	MDeformVert *data_dst = (MDeformVert *)dest;
+	const int idx_src = laymap->data_src_n;
+	const int idx_dst = laymap->data_dst_n;
+
+	const int mix_mode = laymap->mix_mode;
+
+	int i, j;
+
+	MDeformWeight *dw_src;
+	MDeformWeight *dw_dst = defvert_find_index(data_dst, idx_dst);
+	float weight_src = 0.0f, weight_dst = 0.0f;
+
+	if (sources) {
+		for (i = count; i--;) {
+			for (j = data_src[i]->totweight; j--;) {
+				if ((dw_src = &data_src[i]->dw[j])->def_nr == idx_src) {
+					weight_src += dw_src->weight * weights[i];
+					break;
+				}
+			}
+		}
+	}
+
+	if (dw_dst) {
+		weight_dst = dw_dst->weight;
+	}
+	else if (mix_mode == CDT_MIX_REPLACE_ABOVE_THRESHOLD) {
+		return;  /* Do not affect destination. */
+	}
+
+	weight_src = data_transfer_interp_float_do(mix_mode, weight_dst, weight_src, mix_factor);
+
+	CLAMP(weight_src, 0.0f, 1.0f);
+
+	if (!dw_dst) {
+		defvert_add_index_notest(data_dst, idx_dst, weight_src);
+	}
+	else {
+		dw_dst->weight = weight_src;
+	}
+}
+
+static bool data_transfer_layersmapping_vgroups_multisrc_to_dst(
+        ListBase *r_map, const int mix_mode, const float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete,
+        Object *ob_src, Object *ob_dst, MDeformVert *data_src, MDeformVert *data_dst,
+        CustomData *UNUSED(cd_src), CustomData *cd_dst, const bool UNUSED(use_dupref_dst),
+        const int tolayers, bool *use_layers_src, const int num_layers_src)
+{
+	int idx_src;
+	int idx_dst;
+	int tot_dst = BLI_listbase_count(&ob_dst->defbase);
+
+	const size_t elem_size = sizeof(*((MDeformVert *)NULL));
+
+	switch (tolayers) {
+		case DT_LAYERS_INDEX_DST:
+			idx_dst = tot_dst;
+
+			/* Find last source actually used! */
+			idx_src = num_layers_src;
+			while (idx_src-- && !use_layers_src[idx_src]);
+			idx_src++;
+
+			if (idx_dst < idx_src) {
+				if (!use_create) {
+					return false;
+				}
+				/* Create as much vgroups as necessary! */
+				for (; idx_dst < idx_src; idx_dst++) {
+					BKE_object_defgroup_add(ob_dst);
+				}
+			}
+			else if (use_delete && idx_dst > idx_src) {
+				while (idx_dst-- > idx_src) {
+					BKE_object_defgroup_remove(ob_dst, ob_dst->defbase.last);
+				}
+			}
+			if (r_map) {
+				/* At this stage, we **need** a valid CD_MDEFORMVERT layer on dest!
+				 * Again, use_create is not relevant in this case */
+				if (!data_dst) {
+					data_dst = CustomData_add_layer(cd_dst, CD_MDEFORMVERT, CD_CALLOC, NULL, num_elem_dst);
+				}
+
+				while (idx_src--) {
+					if (!use_layers_src[idx_src]) {
+						continue;
+					}
+					data_transfer_layersmapping_add_item(r_map, CD_FAKE_MDEFORMVERT, mix_mode, mix_factor, mix_weights,
+					                                     data_src, data_dst, idx_src, idx_src,
+					                                     elem_size, 0, 0, 0, vgroups_datatransfer_interp);
+				}
+			}
+			break;
+		case DT_LAYERS_NAME_DST:
+			{
+				bDeformGroup *dg_src, *dg_dst;
+
+				if (use_delete) {
+					/* Remove all unused dst vgroups first, simpler in this case. */
+					for (dg_dst = ob_dst->defbase.first; dg_dst;) {
+						bDeformGroup *dg_dst_next = dg_dst->next;
+
+						if (defgroup_name_index(ob_src, dg_dst->name) == -1) {
+							BKE_object_defgroup_remove(ob_dst, dg_dst);
+						}
+						dg_dst = dg_dst_next;
+					}
+				}
+
+				for (idx_src = 0, dg_src = ob_src->defbase.first;
+				     idx_src < num_layers_src;
+				     idx_src++, dg_src = dg_src->next)
+				{
+					if (!use_layers_src[idx_src]) {
+						continue;
+					}
+
+					if ((idx_dst = defgroup_name_index(ob_dst, dg_src->name)) == -1) {
+						if (!use_create) {
+							if (r_map) {
+								BLI_freelistN(r_map);
+							}
+							return false;
+						}
+						BKE_object_defgroup_add_name(ob_dst, dg_src->name);
+						idx_dst = ob_dst->actdef - 1;
+					}
+					if (r_map) {
+						/* At this stage, we **need** a valid CD_MDEFORMVERT layer on dest!
+						 * use_create is not relevant in this case */
+						if (!data_dst) {
+							data_dst = CustomData_add_layer(cd_dst, CD_MDEFORMVERT, CD_CALLOC, NULL, num_elem_dst);
+						}
+
+						data_transfer_layersmapping_add_item(
+						        r_map, CD_FAKE_MDEFORMVERT, mix_mode, mix_factor, mix_weights,
+						        data_src, data_dst, idx_src, idx_dst,
+						        elem_size, 0, 0, 0, vgroups_datatransfer_interp);
+					}
+				}
+				break;
+			}
+		default:
+			return false;
+	}
+
+	return true;
+}
+
+bool data_transfer_layersmapping_vgroups(
+        ListBase *r_map, const int mix_mode, const float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete, Object *ob_src, Object *ob_dst,
+        CustomData *cd_src, CustomData *cd_dst, const bool use_dupref_dst, const int fromlayers, const int tolayers)
+{
+	int idx_src, idx_dst;
+	MDeformVert *data_src, *data_dst = NULL;
+
+	const size_t elem_size = sizeof(*((MDeformVert *)NULL));
+
+	/* Note: VGroups are a bit hairy, since their layout is defined on object level (ob->defbase), while their actual
+	 *       data is a (mesh) CD layer.
+	 *       This implies we may have to handle data layout itself while having NULL data itself,
+	 *       and even have to support NULL data_src in transfer data code (we always create a data_dst, though).
+	 */
+
+	if (BLI_listbase_is_empty(&ob_src->defbase)) {
+		if (use_delete) {
+			BKE_object_defgroup_remove_all(ob_dst);
+		}
+		return true;
+	}
+
+	data_src = CustomData_get_layer(cd_src, CD_MDEFORMVERT);
+
+	data_dst = CustomData_get_layer(cd_dst, CD_MDEFORMVERT);
+	if (data_dst && use_dupref_dst && r_map) {
+		/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+		data_dst = CustomData_duplicate_referenced_layer(cd_dst, CD_MDEFORMVERT, num_elem_dst);
+	}
+
+	if (fromlayers == DT_LAYERS_ACTIVE_SRC || fromlayers >= 0) {
+		/* Note: use_delete has not much meaning in this case, ignored. */
+
+		if (fromlayers >= 0) {
+			idx_src = fromlayers;
+			BLI_assert(idx_src < BLI_listbase_count(&ob_src->defbase));
+		}
+		else if ((idx_src = ob_src->actdef - 1) == -1) {
+			return false;
+		}
+
+		if (tolayers >= 0) {
+			/* Note: in this case we assume layer exists! */
+			idx_dst = tolayers;
+			BLI_assert(idx_dst < BLI_listbase_count(&ob_dst->defbase));
+		}
+		else if (tolayers == DT_LAYERS_ACTIVE_DST) {
+			if ((idx_dst = ob_dst->actdef - 1) == -1) {
+				bDeformGroup *dg_src;
+				if (!use_create) {
+					return true;
+				}
+				dg_src = BLI_findlink(&ob_src->defbase, idx_src);
+				BKE_object_defgroup_add_name(ob_dst, dg_src->name);
+				idx_dst = ob_dst->actdef - 1;
+			}
+		}
+		else if (tolayers == DT_LAYERS_INDEX_DST) {
+			int num = BLI_listbase_count(&ob_src->defbase);
+			idx_dst = idx_src;
+			if (num <= idx_dst) {
+				if (!use_create) {
+					return true;
+				}
+				/* Create as much vgroups as necessary! */
+				for (; num <= idx_dst; num++) {
+					BKE_object_defgroup_add(ob_dst);
+				}
+			}
+		}
+		else if (tolayers == DT_LAYERS_NAME_DST) {
+			bDeformGroup *dg_src = BLI_findlink(&ob_src->defbase, idx_src);
+			if ((idx_dst = defgroup_name_index(ob_dst, dg_src->name)) == -1) {
+				if (!use_create) {
+					return true;
+				}
+				BKE_object_defgroup_add_name(ob_dst, dg_src->name);
+				idx_dst = ob_dst->actdef - 1;
+			}
+		}
+		else {
+			return false;
+		}
+
+		if (r_map) {
+			/* At this stage, we **need** a valid CD_MDEFORMVERT layer on dest!
+			 * use_create is not relevant in this case */
+			if (!data_dst) {
+				data_dst = CustomData_add_layer(cd_dst, CD_MDEFORMVERT, CD_CALLOC, NULL, num_elem_dst);
+			}
+
+			data_transfer_layersmapping_add_item(r_map, CD_FAKE_MDEFORMVERT, mix_mode, mix_factor, mix_weights,
+			                                     data_src, data_dst, idx_src, idx_dst,
+			                                     elem_size, 0, 0, 0, vgroups_datatransfer_interp);
+		}
+	}
+	else {
+		int num_src, num_sel_unused;
+		bool *use_layers_src = NULL;
+		bool ret = false;
+
+		switch (fromlayers) {
+			case DT_LAYERS_ALL_SRC:
+				use_layers_src = BKE_object_defgroup_subset_from_select_type(ob_src, WT_VGROUP_ALL,
+				                                                             &num_src, &num_sel_unused);
+				break;
+			case DT_LAYERS_VGROUP_SRC_BONE_SELECT:
+				use_layers_src = BKE_object_defgroup_subset_from_select_type(ob_src, WT_VGROUP_BONE_SELECT,
+				                                                             &num_src, &num_sel_unused);
+				break;
+			case DT_LAYERS_VGROUP_SRC_BONE_DEFORM:
+				use_layers_src = BKE_object_defgroup_subset_from_select_type(ob_src, WT_VGROUP_BONE_DEFORM,
+				                                                             &num_src, &num_sel_unused);
+				break;
+		}
+
+		if (use_layers_src) {
+			ret = data_transfer_layersmapping_vgroups_multisrc_to_dst(
+			        r_map, mix_mode, mix_factor, mix_weights, num_elem_dst, use_create, use_delete,
+			        ob_src, ob_dst, data_src, data_dst, cd_src, cd_dst, use_dupref_dst,
+			        tolayers, use_layers_src, num_src);
+		}
+
+		MEM_SAFE_FREE(use_layers_src);
+		return ret;
+	}
+
+	return true;
+}
diff --git a/source/blender/blenkernel/intern/object_data_transfer.c b/source/blender/blenkernel/intern/object_data_transfer.c
new file mode 100644
index 00000000000..71320fe9946
--- /dev/null
+++ b/source/blender/blenkernel/intern/object_data_transfer.c
@@ -0,0 +1,1227 @@
+/*
+ * ***** 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) 2014 by Blender Foundation.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Bastien Montagne.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/object_data_transfer.c
+ *  \ingroup bke
+ */
+
+#include "MEM_guardedalloc.h"
+
+#include "DNA_customdata_types.h"
+#include "DNA_meshdata_types.h"
+#include "DNA_mesh_types.h"
+#include "DNA_object_types.h"
+#include "DNA_scene_types.h"
+
+#include "BLI_array.h"
+#include "BLI_math.h"
+#include "BLI_blenlib.h"
+#include "BLI_utildefines.h"
+
+#include "BKE_context.h"
+#include "BKE_customdata.h"
+#include "BKE_object_data_transfer.h"
+#include "BKE_deform.h"
+#include "BKE_DerivedMesh.h"
+#include "BKE_mesh_mapping.h"
+#include "BKE_mesh_remap.h"
+#include "BKE_object.h"
+#include "BKE_object_deform.h"
+#include "BKE_report.h"
+
+#include "data_transfer_intern.h"
+
+
+CustomDataMask BKE_object_data_transfer_dttypes_to_cdmask(const int dtdata_types)
+{
+	CustomDataMask cddata_mask = 0;
+	int i;
+
+	for (i = 0; i < DT_TYPE_MAX; i++) {
+		const int dtdata_type = 1 << i;
+		int cddata_type;
+
+		if (!(dtdata_types & dtdata_type)) {
+			continue;
+		}
+
+		cddata_type = BKE_object_data_transfer_dttype_to_cdtype(dtdata_type);
+		if (!(cddata_type & CD_FAKE)) {
+			cddata_mask |= 1LL << cddata_type;
+		}
+		else if (cddata_type == CD_FAKE_MDEFORMVERT) {
+			cddata_mask |= CD_MASK_MDEFORMVERT;  /* Exception for vgroups :/ */
+		}
+		else if (cddata_type == CD_FAKE_UV) {
+			cddata_mask |= CD_MASK_MTEXPOLY | CD_MASK_MLOOPUV;
+		}
+	}
+
+	return cddata_mask;
+}
+
+/* Check what can do each layer type (if it is actually handled by transferdata, if it supports advanced mixing... */
+bool BKE_object_data_transfer_get_dttypes_capacity(
+        const int dtdata_types, bool *r_advanced_mixing, bool *r_threshold)
+{
+	int i;
+	bool ret = false;
+
+	*r_advanced_mixing = false;
+	*r_threshold = false;
+
+	for (i = 0; (i < DT_TYPE_MAX) && !(ret && *r_advanced_mixing && *r_threshold); i++) {
+		const int dtdata_type = 1 << i;
+
+		if (!(dtdata_types & dtdata_type)) {
+			continue;
+		}
+
+		switch (dtdata_type) {
+		/* Vertex data */
+			case DT_TYPE_MDEFORMVERT:
+				*r_advanced_mixing = true;
+				*r_threshold = true;
+				ret = true;
+				break;
+			case DT_TYPE_SKIN:
+				*r_threshold = true;
+				ret = true;
+				break;
+			case DT_TYPE_BWEIGHT_VERT:
+				ret = true;
+				break;
+		/* Edge data */
+			case DT_TYPE_SHARP_EDGE:
+				*r_threshold = true;
+				ret = true;
+				break;
+			case DT_TYPE_SEAM:
+				*r_threshold = true;
+				ret = true;
+				break;
+			case DT_TYPE_CREASE:
+				ret = true;
+				break;
+			case DT_TYPE_BWEIGHT_EDGE:
+				ret = true;
+				break;
+			case DT_TYPE_FREESTYLE_EDGE:
+				ret = true;
+				break;
+		/* Loop/Poly data */
+			case DT_TYPE_UV:
+				ret = true;
+				break;
+			case DT_TYPE_VCOL:
+				*r_advanced_mixing = true;
+				*r_threshold = true;
+				ret = true;
+				break;
+			case DT_TYPE_SHARP_FACE:
+				ret = true;
+				break;
+			case DT_TYPE_FREESTYLE_FACE:
+				ret = true;
+				break;
+		}
+	}
+
+	return ret;
+}
+
+int BKE_object_data_transfer_get_dttypes_item_types(const int dtdata_types)
+{
+	int i, ret = 0;
+
+	for (i = 0; (i < DT_TYPE_MAX) && (ret ^ (ME_VERT | ME_EDGE | ME_LOOP | ME_POLY)); i++) {
+		const int dtdata_type = 1 << i;
+
+		if (!(dtdata_types & dtdata_type)) {
+			continue;
+		}
+
+		if (DT_DATATYPE_IS_VERT(dtdata_type)) {
+			ret |= ME_VERT;
+		}
+		if (DT_DATATYPE_IS_EDGE(dtdata_type)) {
+			ret |= ME_EDGE;
+		}
+		if (DT_DATATYPE_IS_LOOP(dtdata_type)) {
+			ret |= ME_LOOP;
+		}
+		if (DT_DATATYPE_IS_POLY(dtdata_type)) {
+			ret |= ME_POLY;
+		}
+	}
+
+	return ret;
+}
+
+int BKE_object_data_transfer_dttype_to_cdtype(const int dtdata_type)
+{
+	switch (dtdata_type) {
+		case DT_TYPE_MDEFORMVERT:
+			return CD_FAKE_MDEFORMVERT;
+		case DT_TYPE_SHAPEKEY:
+			return CD_FAKE_SHAPEKEY;
+		case DT_TYPE_SKIN:
+			return CD_MVERT_SKIN;
+		case DT_TYPE_BWEIGHT_VERT:
+			return CD_FAKE_BWEIGHT;
+
+		case DT_TYPE_SHARP_EDGE:
+			return CD_FAKE_SHARP;
+		case DT_TYPE_SEAM:
+			return CD_FAKE_SEAM;
+		case DT_TYPE_CREASE:
+			return CD_FAKE_CREASE;
+		case DT_TYPE_BWEIGHT_EDGE:
+			return CD_FAKE_BWEIGHT;
+		case DT_TYPE_FREESTYLE_EDGE:
+			return CD_FREESTYLE_EDGE;
+
+		case DT_TYPE_UV:
+			return CD_FAKE_UV;
+		case DT_TYPE_SHARP_FACE:
+			return CD_FAKE_SHARP;
+		case DT_TYPE_FREESTYLE_FACE:
+			return CD_FREESTYLE_FACE;
+
+		case DT_TYPE_VCOL:
+			return CD_MLOOPCOL;
+
+		default:
+			BLI_assert(0);
+	}
+	return 0;  /* Should never be reached! */
+}
+
+int BKE_object_data_transfer_dttype_to_srcdst_index(const int dtdata_type)
+{
+	switch (dtdata_type) {
+		case DT_TYPE_MDEFORMVERT:
+			return DT_MULTILAYER_INDEX_MDEFORMVERT;
+		case DT_TYPE_SHAPEKEY:
+			return DT_MULTILAYER_INDEX_SHAPEKEY;
+		case DT_TYPE_UV:
+			return DT_MULTILAYER_INDEX_UV;
+		case DT_TYPE_VCOL:
+			return DT_MULTILAYER_INDEX_VCOL;
+		default:
+			return DT_MULTILAYER_INDEX_INVALID;
+	}
+}
+
+/* ********** */
+
+static MeshRemapIslandsCalc data_transfer_get_loop_islands_generator(const int cddata_type)
+{
+	switch (cddata_type) {
+		case CD_FAKE_UV:
+			return BKE_mesh_calc_islands_loop_poly_uv;
+			break;
+		default:
+			break;
+	}
+	return NULL;
+}
+
+float data_transfer_interp_float_do(
+        const int mix_mode, const float val_dst, const float val_src, const float mix_factor)
+{
+	float val_ret;
+
+	if (((mix_mode == CDT_MIX_REPLACE_ABOVE_THRESHOLD && (val_dst < mix_factor)) ||
+	     (mix_mode == CDT_MIX_REPLACE_BELOW_THRESHOLD && (val_dst > mix_factor))))
+	{
+		return val_dst;  /* Do not affect destination. */
+	}
+
+	switch (mix_mode) {
+		case CDT_MIX_REPLACE_ABOVE_THRESHOLD:
+		case CDT_MIX_REPLACE_BELOW_THRESHOLD:
+			return val_src;
+		case CDT_MIX_MIX:
+			val_ret = (val_dst + val_src) * 0.5f;
+			break;
+		case CDT_MIX_ADD:
+			val_ret = val_dst + val_src;
+			break;
+		case CDT_MIX_SUB:
+			val_ret = val_dst - val_src;
+			break;
+		case CDT_MIX_MUL:
+			val_ret = val_dst * val_src;
+			break;
+		case CDT_MIX_TRANSFER:
+		default:
+			val_ret = val_src;
+			break;
+	}
+	return interpf(val_ret, val_dst, mix_factor);
+}
+
+static void data_transfer_interp_char(const CustomDataTransferLayerMap *laymap, void *dest,
+                                      void **sources, const float *weights, const int count, const float mix_factor)
+{
+	char **data_src = (char **)sources;
+	char *data_dst = (char *)dest;
+
+	const int mix_mode = laymap->mix_mode;
+	float val_src = 0.0f;
+	const float val_dst = (float)(*data_dst) / 255.0f;
+
+	int i;
+
+	for (i = count; i--;) {
+		val_src += ((float)(*data_src[i]) / 255.0f) * weights[i];
+	}
+
+	val_src = data_transfer_interp_float_do(mix_mode, val_dst, val_src, mix_factor);
+
+	CLAMP(val_src, 0.0f, 1.0f);
+
+	*data_dst = (char)(val_src * 255.0f);
+}
+
+/* Helpers to match sources and destinations data layers (also handles 'conversions' in CD_FAKE cases). */
+
+void data_transfer_layersmapping_add_item(
+        ListBase *r_map, const int cddata_type, const int mix_mode, const float mix_factor, const float *mix_weights,
+        void *data_src, void *data_dst, const int data_src_n, const int data_dst_n,
+        const size_t elem_size, const size_t data_size, const size_t data_offset, const uint64_t data_flag,
+        cd_datatransfer_interp interp)
+{
+	CustomDataTransferLayerMap *item = MEM_mallocN(sizeof(*item), __func__);
+
+	BLI_assert(data_dst != NULL);
+
+	item->data_type = cddata_type;
+	item->mix_mode = mix_mode;
+	item->mix_factor = mix_factor;
+	item->mix_weights = mix_weights;
+
+	item->data_src = data_src;
+	item->data_dst = data_dst;
+	item->data_src_n = data_src_n;
+	item->data_dst_n = data_dst_n;
+	item->elem_size = elem_size;
+
+	item->data_size = data_size;
+	item->data_offset = data_offset;
+	item->data_flag = data_flag;
+
+	item->interp = interp;
+
+	BLI_addtail(r_map, item);
+}
+
+static void data_transfer_layersmapping_add_item_cd(
+        ListBase *r_map, const int cddata_type, const int mix_mode, const float mix_factor, const float *mix_weights,
+        void *data_src, void *data_dst)
+{
+	data_transfer_layersmapping_add_item(
+	        r_map, cddata_type, mix_mode, mix_factor, mix_weights, data_src, data_dst,
+	        0, 0, 0, 0, 0, 0, NULL);
+}
+
+/* Note: All those layer mapping handlers return false *only* if they were given invalid parameters.
+ *       This means that even if they do nothing, they will return true if all given parameters were OK.
+ *       Also, r_map may be NULL, in which case they will 'only' create/delete destination layers according
+ *       to given parameters.
+ */
+
+static bool data_transfer_layersmapping_cdlayers_multisrc_to_dst(
+        ListBase *r_map, const int cddata_type, const int mix_mode, const float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete,
+        CustomData *cd_src, CustomData *cd_dst, const bool use_dupref_dst,
+        const int tolayers, bool *use_layers_src, const int num_layers_src)
+{
+	void *data_src, *data_dst = NULL;
+	int idx_src = num_layers_src;
+	int idx_dst, tot_dst = CustomData_number_of_layers(cd_dst, cddata_type);
+	bool *data_dst_to_delete = NULL;
+
+	switch (tolayers) {
+		case DT_LAYERS_INDEX_DST:
+			idx_dst = tot_dst;
+
+			/* Find last source actually used! */
+			while (idx_src-- && !use_layers_src[idx_src]);
+			idx_src++;
+
+			if (idx_dst < idx_src) {
+				if (!use_create) {
+					return true;
+				}
+				/* Create as much data layers as necessary! */
+				for (; idx_dst < idx_src; idx_dst++) {
+					CustomData_add_layer(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst);
+				}
+			}
+			else if (use_delete && idx_dst > idx_src) {
+				while (idx_dst-- > idx_src) {
+					CustomData_free_layer(cd_dst, cddata_type, num_elem_dst, idx_dst);
+				}
+			}
+			if (r_map) {
+				while (idx_src--) {
+					if (!use_layers_src[idx_src]) {
+						continue;
+					}
+					data_src = CustomData_get_layer_n(cd_src, cddata_type, idx_src);
+					/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+					if (use_dupref_dst) {
+						data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_src, num_elem_dst);
+					}
+					else {
+						data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_src);
+					}
+					data_transfer_layersmapping_add_item_cd(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+					                                        data_src, data_dst);
+				}
+			}
+			break;
+		case DT_LAYERS_NAME_DST:
+			if (use_delete) {
+				if (tot_dst) {
+					data_dst_to_delete = MEM_mallocN(sizeof(*data_dst_to_delete) * (size_t)tot_dst, __func__);
+					memset(data_dst_to_delete, true, sizeof(*data_dst_to_delete) * (size_t)tot_dst);
+				}
+			}
+
+			while (idx_src--) {
+				const char *name;
+
+				if (!use_layers_src[idx_src]) {
+					continue;
+				}
+
+				name = CustomData_get_layer_name(cd_src, cddata_type, idx_src);
+				data_src = CustomData_get_layer_n(cd_src, cddata_type, idx_src);
+
+				if ((idx_dst = CustomData_get_named_layer(cd_dst, cddata_type, name)) == -1) {
+					if (!use_create) {
+						if (r_map) {
+							BLI_freelistN(r_map);
+						}
+						return true;
+					}
+					CustomData_add_layer_named(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst, name);
+					idx_dst = CustomData_get_named_layer(cd_dst, cddata_type, name);
+				}
+				else if (data_dst_to_delete) {
+					data_dst_to_delete[idx_dst] = false;
+				}
+				if (r_map) {
+					/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+					if (use_dupref_dst) {
+						data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_dst, num_elem_dst);
+					}
+					else {
+						data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_dst);
+					}
+					data_transfer_layersmapping_add_item_cd(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+					                                        data_src, data_dst);
+				}
+			}
+
+			if (data_dst_to_delete) {
+				/* Note: This won't affect newly created layers, if any, since tot_dst has not been updated!
+				 *       Also, looping backward ensures us we do not suffer from index shifting when deleting a layer.
+				 */
+				for (idx_dst = tot_dst; idx_dst--;) {
+					if (data_dst_to_delete[idx_dst]) {
+						CustomData_free_layer(cd_dst, cddata_type, num_elem_dst, idx_dst);
+					}
+				}
+
+				MEM_freeN(data_dst_to_delete);
+			}
+			break;
+		default:
+			return false;
+	}
+
+	return true;
+}
+
+static bool data_transfer_layersmapping_cdlayers(
+        ListBase *r_map, const int cddata_type, const int mix_mode, const float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete,
+        CustomData *cd_src, CustomData *cd_dst, const bool use_dupref_dst,
+        const int fromlayers, const int tolayers)
+{
+	int idx_src, idx_dst;
+	void *data_src, *data_dst = NULL;
+
+	if (CustomData_layertype_is_singleton(cddata_type)) {
+		if (!(data_src = CustomData_get_layer(cd_src, cddata_type))) {
+			if (use_delete) {
+				CustomData_free_layer(cd_dst, cddata_type, num_elem_dst, 0);
+			}
+			return true;
+		}
+
+		data_dst = CustomData_get_layer(cd_dst, cddata_type);
+		if (!data_dst) {
+			if (!use_create) {
+				return true;
+			}
+			data_dst = CustomData_add_layer(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst);
+		}
+		else if (use_dupref_dst && r_map) {
+			/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+			data_dst = CustomData_duplicate_referenced_layer(cd_dst, cddata_type, num_elem_dst);
+		}
+
+		if (r_map) {
+			data_transfer_layersmapping_add_item_cd(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			                                        data_src, data_dst);
+		}
+	}
+	else if (fromlayers == DT_LAYERS_ACTIVE_SRC || fromlayers >= 0) {
+		/* Note: use_delete has not much meaning in this case, ignored. */
+
+		if (fromlayers >= 0) {  /* Real-layer index */
+			idx_src = fromlayers;
+		}
+		else {
+			if ((idx_src = CustomData_get_active_layer(cd_src, cddata_type)) == -1) {
+				return true;
+			}
+		}
+		data_src = CustomData_get_layer_n(cd_src, cddata_type, idx_src);
+		if (!data_src) {
+			return true;
+		}
+
+		if (tolayers >= 0) {  /* Real-layer index */
+			idx_dst = tolayers;
+			/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+			if (use_dupref_dst && r_map) {
+				data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_dst, num_elem_dst);
+			}
+			else {
+				data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_dst);
+			}
+		}
+		else if (tolayers == DT_LAYERS_ACTIVE_DST) {
+			if ((idx_dst = CustomData_get_active_layer(cd_dst, cddata_type)) == -1) {
+				if (!use_create) {
+					return true;
+				}
+				data_dst = CustomData_add_layer(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst);
+			}
+			else {
+				/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+				if (use_dupref_dst && r_map) {
+					data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_dst, num_elem_dst);
+				}
+				else {
+					data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_dst);
+				}
+			}
+		}
+		else if (tolayers == DT_LAYERS_INDEX_DST) {
+			int num = CustomData_number_of_layers(cd_dst, cddata_type);
+			idx_dst = idx_src;
+			if (num <= idx_dst) {
+				if (!use_create) {
+					return true;
+				}
+				/* Create as much data layers as necessary! */
+				for (; num <= idx_dst; num++) {
+					CustomData_add_layer(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst);
+				}
+			}
+			/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+			if (use_dupref_dst && r_map) {
+				data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_dst, num_elem_dst);
+			}
+			else {
+				data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_dst);
+			}
+		}
+		else if (tolayers == DT_LAYERS_NAME_DST) {
+			const char *name = CustomData_get_layer_name(cd_src, cddata_type, idx_src);
+			if ((idx_dst = CustomData_get_named_layer(cd_dst, cddata_type, name)) == -1) {
+				if (!use_create) {
+					return true;
+				}
+				CustomData_add_layer_named(cd_dst, cddata_type, CD_CALLOC, NULL, num_elem_dst, name);
+				idx_dst = CustomData_get_named_layer(cd_dst, cddata_type, name);
+			}
+			/* If dest is a derivedmesh, we do not want to overwrite cdlayers of org mesh! */
+			if (use_dupref_dst && r_map) {
+				data_dst = CustomData_duplicate_referenced_layer_n(cd_dst, cddata_type, idx_dst, num_elem_dst);
+			}
+			else {
+				data_dst = CustomData_get_layer_n(cd_dst, cddata_type, idx_dst);
+			}
+		}
+		else {
+			return false;
+		}
+
+		if (!data_dst) {
+			return false;
+		}
+
+		if (r_map) {
+			data_transfer_layersmapping_add_item_cd(
+			        r_map, cddata_type, mix_mode, mix_factor, mix_weights, data_src, data_dst);
+		}
+	}
+	else if (fromlayers == DT_LAYERS_ALL_SRC) {
+		int num_src = CustomData_number_of_layers(cd_src, cddata_type);
+		bool *use_layers_src = num_src ? MEM_mallocN(sizeof(*use_layers_src) * (size_t)num_src, __func__) : NULL;
+		bool ret;
+
+		if (use_layers_src) {
+			memset(use_layers_src, true, sizeof(*use_layers_src) * num_src);
+		}
+
+		ret = data_transfer_layersmapping_cdlayers_multisrc_to_dst(
+		        r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+		        num_elem_dst, use_create, use_delete, cd_src, cd_dst, use_dupref_dst,
+		        tolayers, use_layers_src, num_src);
+
+		if (use_layers_src) {
+			MEM_freeN(use_layers_src);
+		}
+		return ret;
+	}
+	else {
+		return false;
+	}
+
+	return true;
+}
+
+static bool data_transfer_layersmapping_generate(
+        ListBase *r_map, Object *ob_src, Object *ob_dst, DerivedMesh *dm_src, DerivedMesh *dm_dst, Mesh *me_dst,
+        const int elem_type, int cddata_type, int mix_mode, float mix_factor, const float *mix_weights,
+        const int num_elem_dst, const bool use_create, const bool use_delete, const int fromlayers, const int tolayers)
+{
+	CustomData *cd_src, *cd_dst;
+
+	if (elem_type == ME_VERT) {
+		if (!(cddata_type & CD_FAKE)) {
+			cd_src = dm_src->getVertDataLayout(dm_src);
+			cd_dst = dm_dst ? dm_dst->getVertDataLayout(dm_dst) : &me_dst->vdata;
+
+			if (!data_transfer_layersmapping_cdlayers(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			                                          num_elem_dst, use_create, use_delete,
+			                                          cd_src, cd_dst, dm_dst != NULL,
+			                                          fromlayers, tolayers))
+			{
+				/* We handle specific source selection cases here. */
+				return false;
+			}
+			return true;
+		}
+		else if (cddata_type == CD_FAKE_BWEIGHT) {
+			const size_t elem_size = sizeof(*((MVert *)NULL));
+			const size_t data_size = sizeof(((MVert *)NULL)->bweight);
+			const size_t data_offset = offsetof(MVert, bweight);
+			const uint64_t data_flag = 0;
+
+			if (!(dm_src->cd_flag & ME_CDFLAG_VERT_BWEIGHT)) {
+				if (use_delete && !dm_dst) {
+					me_dst->cd_flag &= ~ME_CDFLAG_VERT_BWEIGHT;
+				}
+				return true;
+			}
+			if (dm_dst) {
+				dm_dst->cd_flag |= ME_CDFLAG_VERT_BWEIGHT;
+			}
+			else {
+				me_dst->cd_flag |= ME_CDFLAG_VERT_BWEIGHT;
+			}
+			if (r_map) {
+				data_transfer_layersmapping_add_item(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+				                                     dm_src->getVertArray(dm_src),
+				                                     dm_dst ? dm_dst->getVertArray(dm_dst) : me_dst->mvert,
+				                                     dm_src->getNumVerts(dm_src),
+				                                     dm_dst ? dm_dst->getNumVerts(dm_dst) : me_dst->totvert,
+				                                     elem_size, data_size, data_offset, data_flag,
+				                                     data_transfer_interp_char);
+			}
+			return true;
+		}
+		else if (cddata_type == CD_FAKE_MDEFORMVERT) {
+			cd_src = dm_src->getVertDataLayout(dm_src);
+			cd_dst = dm_dst ? dm_dst->getVertDataLayout(dm_dst) : &me_dst->vdata;
+
+			return data_transfer_layersmapping_vgroups(r_map, mix_mode, mix_factor, mix_weights,
+			                                           num_elem_dst, use_create, use_delete,
+			                                           ob_src, ob_dst, cd_src, cd_dst, dm_dst != NULL,
+			                                           fromlayers, tolayers);
+		}
+		else if (cddata_type == CD_FAKE_SHAPEKEY) {
+			/* TODO: leaving shapekeys asside for now, quite specific case, since we can't access them from MVert :/ */
+			return false;
+		}
+	}
+	else if (elem_type == ME_EDGE) {
+		if (!(cddata_type & CD_FAKE)) {  /* Unused for edges, currently... */
+			cd_src = dm_src->getEdgeDataLayout(dm_src);
+			cd_dst = dm_dst ? dm_dst->getEdgeDataLayout(dm_dst) : &me_dst->edata;
+
+			if (!data_transfer_layersmapping_cdlayers(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			                                          num_elem_dst, use_create, use_delete,
+			                                          cd_src, cd_dst, dm_dst != NULL,
+			                                          fromlayers, tolayers))
+			{
+				/* We handle specific source selection cases here. */
+				return false;
+			}
+			return true;
+		}
+		else if (cddata_type == CD_FAKE_CREASE) {
+			const size_t elem_size = sizeof(*((MEdge *)NULL));
+			const size_t data_size = sizeof(((MEdge *)NULL)->crease);
+			const size_t data_offset = offsetof(MEdge, crease);
+			const uint64_t data_flag = 0;
+
+			if (!(dm_src->cd_flag & ME_CDFLAG_EDGE_CREASE)) {
+				if (use_delete && !dm_dst) {
+					me_dst->cd_flag &= ~ME_CDFLAG_EDGE_CREASE;
+				}
+				return true;
+			}
+			if (dm_dst) {
+				dm_dst->cd_flag |= ME_CDFLAG_EDGE_CREASE;
+			}
+			else {
+				me_dst->cd_flag |= ME_CDFLAG_EDGE_CREASE;
+			}
+			if (r_map) {
+				data_transfer_layersmapping_add_item(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+				                                     dm_src->getEdgeArray(dm_src),
+				                                     dm_dst ? dm_dst->getEdgeArray(dm_dst) : me_dst->medge,
+				                                     dm_src->getNumEdges(dm_src),
+				                                     dm_dst ? dm_dst->getNumEdges(dm_dst) : me_dst->totedge,
+				                                     elem_size, data_size, data_offset, data_flag,
+				                                     data_transfer_interp_char);
+			}
+			return true;
+		}
+		else if (cddata_type == CD_FAKE_BWEIGHT) {
+			const size_t elem_size = sizeof(*((MEdge *)NULL));
+			const size_t data_size = sizeof(((MEdge *)NULL)->bweight);
+			const size_t data_offset = offsetof(MEdge, bweight);
+			const uint64_t data_flag = 0;
+
+			if (!(dm_src->cd_flag & ME_CDFLAG_EDGE_BWEIGHT)) {
+				if (use_delete && !dm_dst) {
+					me_dst->cd_flag &= ~ME_CDFLAG_EDGE_BWEIGHT;
+				}
+				return true;
+			}
+			if (dm_dst) {
+				dm_dst->cd_flag |= ME_CDFLAG_EDGE_BWEIGHT;
+			}
+			else {
+				me_dst->cd_flag |= ME_CDFLAG_EDGE_BWEIGHT;
+			}
+			if (r_map) {
+				data_transfer_layersmapping_add_item(r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+				                                     dm_src->getEdgeArray(dm_src),
+				                                     dm_dst ? dm_dst->getEdgeArray(dm_dst) : me_dst->medge,
+				                                     dm_src->getNumEdges(dm_src),
+				                                     dm_dst ? dm_dst->getNumEdges(dm_dst) : me_dst->totedge,
+				                                     elem_size, data_size, data_offset, data_flag,
+				                                     data_transfer_interp_char);
+			}
+			return true;
+		}
+		else if (r_map && ELEM(cddata_type, CD_FAKE_SHARP, CD_FAKE_SEAM)) {
+			const size_t elem_size = sizeof(*((MEdge *)NULL));
+			const size_t data_size = sizeof(((MEdge *)NULL)->flag);
+			const size_t data_offset = offsetof(MEdge, flag);
+			const uint64_t data_flag = (cddata_type == CD_FAKE_SHARP) ? ME_SHARP : ME_SEAM;
+
+			data_transfer_layersmapping_add_item(
+			        r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			        dm_src->getEdgeArray(dm_src),
+			        dm_dst ? dm_dst->getEdgeArray(dm_dst) : me_dst->medge,
+			        dm_src->getNumEdges(dm_src),
+			        dm_dst ? dm_dst->getNumEdges(dm_dst) : me_dst->totedge,
+			        elem_size, data_size, data_offset, data_flag, NULL);
+			return true;
+		}
+		else {
+			return false;
+		}
+	}
+	else if (elem_type == ME_LOOP) {
+		if (cddata_type == CD_FAKE_UV) {
+			cddata_type = CD_MLOOPUV;
+		}
+
+		if (!(cddata_type & CD_FAKE)) {
+			cd_src = dm_src->getLoopDataLayout(dm_src);
+			cd_dst = dm_dst ? dm_dst->getLoopDataLayout(dm_dst) : &me_dst->ldata;
+
+			if (!data_transfer_layersmapping_cdlayers(
+			        r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			        num_elem_dst, use_create, use_delete, cd_src, cd_dst, dm_dst != NULL,
+			        fromlayers, tolayers))
+			{
+				/* We handle specific source selection cases here. */
+				return false;
+			}
+			return true;
+		}
+		else {
+			return false;
+		}
+	}
+	else if (elem_type == ME_POLY) {
+		if (cddata_type == CD_FAKE_UV) {
+			cddata_type = CD_MTEXPOLY;
+		}
+
+		if (!(cddata_type & CD_FAKE)) {
+			cd_src = dm_src->getPolyDataLayout(dm_src);
+			cd_dst = dm_dst ? dm_dst->getPolyDataLayout(dm_dst) : &me_dst->pdata;
+
+			if (!data_transfer_layersmapping_cdlayers(
+			        r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			        num_elem_dst, use_create, use_delete, cd_src, cd_dst, dm_dst != NULL,
+			        fromlayers, tolayers))
+			{
+				/* We handle specific source selection cases here. */
+				return false;
+			}
+			return true;
+		}
+		else if (r_map && cddata_type == CD_FAKE_SHARP) {
+			const size_t elem_size = sizeof(*((MPoly *)NULL));
+			const size_t data_size = sizeof(((MPoly *)NULL)->flag);
+			const size_t data_offset = offsetof(MPoly, flag);
+			const uint64_t data_flag = ME_SMOOTH;
+
+			data_transfer_layersmapping_add_item(
+			        r_map, cddata_type, mix_mode, mix_factor, mix_weights,
+			        dm_src->getPolyArray(dm_src),
+			        dm_dst ? dm_dst->getPolyArray(dm_dst) : me_dst->mpoly,
+			        dm_src->getNumPolys(dm_src),
+			        dm_dst ? dm_dst->getNumPolys(dm_dst) : me_dst->totpoly,
+			        elem_size, data_size, data_offset, data_flag, NULL);
+			return true;
+		}
+		else {
+			return false;
+		}
+	}
+
+	return false;
+}
+
+/**
+ * Transfer data *layout* of selected types from source to destination object.
+ * By default, it only creates new data layers if needed on \a ob_dst.
+ * If \a use_delete is true, it will also delete data layers on \a ob_dst that do not match those from \a ob_src,
+ * to get (as much as possible) exact copy of source data layout.
+ */
+void BKE_object_data_transfer_layout(
+        Scene *scene, Object *ob_src, Object *ob_dst, const int data_types, const bool use_delete,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX])
+{
+	DerivedMesh *dm_src;
+	Mesh *me_dst;
+	int i;
+
+	const bool use_create = true;  /* We always create needed layers here. */
+
+	CustomDataMask dm_src_mask = CD_MASK_BAREMESH;
+
+	BLI_assert((ob_src != ob_dst) && (ob_src->type == OB_MESH) && (ob_dst->type == OB_MESH));
+
+	me_dst = ob_dst->data;
+
+	/* Get source DM.*/
+	dm_src_mask |= BKE_object_data_transfer_dttypes_to_cdmask(data_types);
+	dm_src = mesh_get_derived_final(scene, ob_src, dm_src_mask);
+	if (!dm_src) {
+		return;
+	}
+
+	/* Check all possible data types. */
+	for (i = 0; i < DT_TYPE_MAX; i++) {
+		const int dtdata_type = 1 << i;
+		int cddata_type;
+		int fromlayers, tolayers, fromto_idx;
+
+		if (!(data_types & dtdata_type)) {
+			continue;
+		}
+
+		cddata_type = BKE_object_data_transfer_dttype_to_cdtype(dtdata_type);
+
+		fromto_idx = BKE_object_data_transfer_dttype_to_srcdst_index(dtdata_type);
+		if (fromto_idx != DT_MULTILAYER_INDEX_INVALID) {
+			fromlayers = fromlayers_select[fromto_idx];
+			tolayers = tolayers_select[fromto_idx];
+		}
+		else {
+			fromlayers = tolayers = 0;
+		}
+
+		if (DT_DATATYPE_IS_VERT(dtdata_type)) {
+			const int num_elem_dst = me_dst->totvert;
+
+			data_transfer_layersmapping_generate(
+			        NULL, ob_src, ob_dst, dm_src, NULL, me_dst, ME_VERT, cddata_type, 0, 0.0f, NULL,
+			        num_elem_dst, use_create, use_delete, fromlayers, tolayers);
+		}
+		if (DT_DATATYPE_IS_EDGE(dtdata_type)) {
+			const int num_elem_dst = me_dst->totedge;
+
+			data_transfer_layersmapping_generate(
+			        NULL, ob_src, ob_dst, dm_src, NULL, me_dst, ME_EDGE, cddata_type, 0, 0.0f, NULL,
+			        num_elem_dst, use_create, use_delete, fromlayers, tolayers);
+		}
+		if (DT_DATATYPE_IS_LOOP(dtdata_type)) {
+			const int num_elem_dst = me_dst->totloop;
+
+			data_transfer_layersmapping_generate(
+			        NULL, ob_src, ob_dst, dm_src, NULL, me_dst, ME_LOOP, cddata_type, 0, 0.0f, NULL,
+			        num_elem_dst, use_create, use_delete, fromlayers, tolayers);
+		}
+		if (DT_DATATYPE_IS_POLY(dtdata_type)) {
+			const int num_elem_dst = me_dst->totpoly;
+
+			data_transfer_layersmapping_generate(
+			        NULL, ob_src, ob_dst, dm_src, NULL, me_dst, ME_POLY, cddata_type, 0, 0.0f, NULL,
+			        num_elem_dst, use_create, use_delete, fromlayers, tolayers);
+		}
+	}
+}
+
+bool BKE_object_data_transfer_dm(
+        Scene *scene, Object *ob_src, Object *ob_dst, DerivedMesh *dm_dst, const int data_types, bool use_create,
+        const int map_vert_mode, const int map_edge_mode, const int map_loop_mode, const int map_poly_mode,
+        SpaceTransform *space_transform, const float max_distance, const float ray_radius,
+        const float islands_handling_precision,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX],
+        const int mix_mode, const float mix_factor, const char *vgroup_name, const bool invert_vgroup,
+        ReportList *reports)
+{
+#define VDATA 0
+#define EDATA 1
+#define LDATA 2
+#define PDATA 3
+#define DATAMAX 4
+
+	DerivedMesh *dm_src;
+	Mesh *me_dst;
+	bool dirty_nors_dst = true;  /* Assumed always true if not using a dm as destination. */
+	int i;
+
+	MDeformVert *mdef = NULL;
+	int vg_idx = -1;
+	float *weights[DATAMAX] = {NULL};
+
+	MeshPairRemap geom_map[DATAMAX] = {{0}};
+	bool geom_map_init[DATAMAX] = {0};
+	ListBase lay_map = {0};
+	bool changed = false;
+
+	const bool use_delete = false;  /* We never delete data layers from destination here. */
+
+	CustomDataMask dm_src_mask = CD_MASK_BAREMESH;
+
+	BLI_assert((ob_src != ob_dst) && (ob_src->type == OB_MESH) && (ob_dst->type == OB_MESH));
+
+	me_dst = ob_dst->data;
+	if (dm_dst) {
+		dirty_nors_dst = (dm_dst->dirty & DM_DIRTY_NORMALS) != 0;
+		use_create = false;  /* Never create needed custom layers on DM (modifier case). */
+	}
+
+	if (vgroup_name) {
+		if (dm_dst) {
+			mdef = dm_dst->getVertDataArray(dm_dst, CD_MDEFORMVERT);
+		}
+		else {
+			mdef = CustomData_get_layer(&me_dst->vdata, CD_MDEFORMVERT);
+		}
+		if (mdef) {
+			vg_idx = defgroup_name_index(ob_dst, vgroup_name);
+		}
+	}
+
+	/* Get source DM.*/
+	dm_src_mask |= BKE_object_data_transfer_dttypes_to_cdmask(data_types);
+	/* XXX Hack! In case this is being evaluated from dm stack, we cannot compute final dm,
+	 *     can lead to infinite recursion in case of dependency cycles of DataTransfer modifiers...
+	 *     Issue is, this means we cannot be sure to have requested cd layers in source.
+	 */
+	dm_src = dm_dst ? ob_src->derivedFinal : mesh_get_derived_final(scene, ob_src, dm_src_mask);
+	if (!dm_src) {
+		return changed;
+	}
+
+	/* Check all possible data types.
+	 * Note item mappings and dest mix weights are cached. */
+	for (i = 0; i < DT_TYPE_MAX; i++) {
+		const int dtdata_type = 1 << i;
+		int cddata_type;
+		int fromlayers, tolayers, fromto_idx;
+
+		if (!(data_types & dtdata_type)) {
+			continue;
+		}
+
+		cddata_type = BKE_object_data_transfer_dttype_to_cdtype(dtdata_type);
+
+		fromto_idx = BKE_object_data_transfer_dttype_to_srcdst_index(dtdata_type);
+		if (fromto_idx != DT_MULTILAYER_INDEX_INVALID) {
+			fromlayers = fromlayers_select[fromto_idx];
+			tolayers = tolayers_select[fromto_idx];
+		}
+		else {
+			fromlayers = tolayers = 0;
+		}
+
+		if (DT_DATATYPE_IS_VERT(dtdata_type)) {
+			MVert *verts_dst = dm_dst ? dm_dst->getVertArray(dm_dst) : me_dst->mvert;
+			const int num_verts_dst = dm_dst ? dm_dst->getNumVerts(dm_dst) : me_dst->totvert;
+
+			if (!geom_map_init[VDATA]) {
+				if ((map_vert_mode == MREMAP_MODE_TOPOLOGY) && (num_verts_dst != dm_src->getNumVerts(dm_src))) {
+					BKE_report(reports, RPT_ERROR,
+					           "Source and destination meshes do not have the same amount of vertices, "
+					           "'Topology' mapping cannot be used in this case");
+					return changed;
+				}
+				BKE_mesh_remap_calc_verts_from_dm(
+				        map_vert_mode, space_transform, max_distance, ray_radius,
+				        verts_dst, num_verts_dst, dirty_nors_dst, dm_src, &geom_map[VDATA]);
+				geom_map_init[VDATA] = true;
+			}
+
+			if (mdef && vg_idx != -1 && !weights[VDATA]) {
+				weights[VDATA] = MEM_mallocN(sizeof(*(weights[VDATA])) * (size_t)num_verts_dst, __func__);
+				BKE_defvert_extract_vgroup_to_vertweights(mdef, vg_idx, num_verts_dst, weights[VDATA], invert_vgroup);
+			}
+
+			if (data_transfer_layersmapping_generate(
+			        &lay_map, ob_src, ob_dst, dm_src, dm_dst, me_dst, ME_VERT,
+			        cddata_type, mix_mode, mix_factor, weights[VDATA],
+			        num_verts_dst, use_create, use_delete, fromlayers, tolayers))
+			{
+				CustomDataTransferLayerMap *lay_mapit;
+
+				changed = (lay_map.first != NULL);
+
+				for (lay_mapit = lay_map.first; lay_mapit; lay_mapit = lay_mapit->next) {
+					CustomData_data_transfer(&geom_map[VDATA], lay_mapit);
+				}
+
+				BLI_freelistN(&lay_map);
+			}
+		}
+		if (DT_DATATYPE_IS_EDGE(dtdata_type)) {
+			MVert *verts_dst = dm_dst ? dm_dst->getVertArray(dm_dst) : me_dst->mvert;
+			const int num_verts_dst = dm_dst ? dm_dst->getNumVerts(dm_dst) : me_dst->totvert;
+			MEdge *edges_dst = dm_dst ? dm_dst->getEdgeArray(dm_dst) : me_dst->medge;
+			const int num_edges_dst = dm_dst ? dm_dst->getNumEdges(dm_dst) : me_dst->totedge;
+
+			if (!geom_map_init[EDATA]) {
+				if ((map_edge_mode == MREMAP_MODE_TOPOLOGY) && (num_edges_dst != dm_src->getNumEdges(dm_src))) {
+					BKE_report(reports, RPT_ERROR,
+					           "Source and destination meshes do not have the same amount of edges, "
+					           "'Topology' mapping cannot be used in this case");
+					return changed;
+				}
+				BKE_mesh_remap_calc_edges_from_dm(
+				        map_edge_mode, space_transform, max_distance, ray_radius,
+				        verts_dst, num_verts_dst, edges_dst, num_edges_dst, dirty_nors_dst,
+				        dm_src, &geom_map[EDATA]);
+				geom_map_init[EDATA] = true;
+			}
+
+			if (mdef && vg_idx != -1 && !weights[EDATA]) {
+				weights[EDATA] = MEM_mallocN(sizeof(*weights[EDATA]) * (size_t)num_edges_dst, __func__);
+				BKE_defvert_extract_vgroup_to_edgeweights(
+				        mdef, vg_idx, num_verts_dst, edges_dst, num_edges_dst,
+				        weights[EDATA], invert_vgroup);
+			}
+
+			if (data_transfer_layersmapping_generate(
+			        &lay_map, ob_src, ob_dst, dm_src, dm_dst, me_dst, ME_EDGE,
+			        cddata_type, mix_mode, mix_factor, weights[EDATA],
+			        num_edges_dst, use_create, use_delete, fromlayers, tolayers))
+			{
+				CustomDataTransferLayerMap *lay_mapit;
+
+				changed = (lay_map.first != NULL);
+
+				for (lay_mapit = lay_map.first; lay_mapit; lay_mapit = lay_mapit->next) {
+					CustomData_data_transfer(&geom_map[EDATA], lay_mapit);
+				}
+
+				BLI_freelistN(&lay_map);
+			}
+		}
+		if (DT_DATATYPE_IS_LOOP(dtdata_type)) {
+			MVert *verts_dst = dm_dst ? dm_dst->getVertArray(dm_dst) : me_dst->mvert;
+			const int num_verts_dst = dm_dst ? dm_dst->getNumVerts(dm_dst) : me_dst->totvert;
+			MEdge *edges_dst = dm_dst ? dm_dst->getEdgeArray(dm_dst) : me_dst->medge;
+			const int num_edges_dst = dm_dst ? dm_dst->getNumEdges(dm_dst) : me_dst->totedge;
+			MPoly *polys_dst = dm_dst ? dm_dst->getPolyArray(dm_dst) : me_dst->mpoly;
+			const int num_polys_dst = dm_dst ? dm_dst->getNumPolys(dm_dst) : me_dst->totpoly;
+			MLoop *loops_dst = dm_dst ? dm_dst->getLoopArray(dm_dst) : me_dst->mloop;
+			const int num_loops_dst = dm_dst ? dm_dst->getNumLoops(dm_dst) : me_dst->totloop;
+			CustomData *pdata_dst = dm_dst ? dm_dst->getPolyDataLayout(dm_dst) : &me_dst->pdata;
+			CustomData *ldata_dst = dm_dst ? dm_dst->getLoopDataLayout(dm_dst) : &me_dst->ldata;
+
+			MeshRemapIslandsCalc island_callback = data_transfer_get_loop_islands_generator(cddata_type);
+
+			if (!geom_map_init[LDATA]) {
+				if ((map_loop_mode == MREMAP_MODE_TOPOLOGY) && (num_loops_dst != dm_src->getNumLoops(dm_src))) {
+					BKE_report(reports, RPT_ERROR,
+					           "Source and destination meshes do not have the same amount of face corners, "
+					           "'Topology' mapping cannot be used in this case");
+					return changed;
+				}
+				BKE_mesh_remap_calc_loops_from_dm(
+				        map_loop_mode, space_transform, max_distance, ray_radius,
+				        verts_dst, num_verts_dst, edges_dst, num_edges_dst,
+				        loops_dst, num_loops_dst, polys_dst, num_polys_dst,
+				        ldata_dst, pdata_dst, me_dst->smoothresh, dirty_nors_dst,
+				        dm_src, island_callback, islands_handling_precision, &geom_map[LDATA]);
+				geom_map_init[LDATA] = true;
+			}
+
+			if (mdef && vg_idx != -1 && !weights[LDATA]) {
+				weights[LDATA] = MEM_mallocN(sizeof(*weights[LDATA]) * (size_t)num_loops_dst, __func__);
+				BKE_defvert_extract_vgroup_to_loopweights(
+				        mdef, vg_idx, num_verts_dst, loops_dst, num_loops_dst,
+				        weights[LDATA], invert_vgroup);
+			}
+
+			if (data_transfer_layersmapping_generate(
+			        &lay_map, ob_src, ob_dst, dm_src, dm_dst, me_dst, ME_LOOP,
+			        cddata_type, mix_mode, mix_factor, weights[LDATA],
+			        num_loops_dst, use_create, use_delete, fromlayers, tolayers))
+			{
+				CustomDataTransferLayerMap *lay_mapit;
+
+				changed = (lay_map.first != NULL);
+
+				for (lay_mapit = lay_map.first; lay_mapit; lay_mapit = lay_mapit->next) {
+					CustomData_data_transfer(&geom_map[LDATA], lay_mapit);
+				}
+
+				BLI_freelistN(&lay_map);
+			}
+		}
+		if (DT_DATATYPE_IS_POLY(dtdata_type)) {
+			MVert *verts_dst = dm_dst ? dm_dst->getVertArray(dm_dst) : me_dst->mvert;
+			const int num_verts_dst = dm_dst ? dm_dst->getNumVerts(dm_dst) : me_dst->totvert;
+			MPoly *polys_dst = dm_dst ? dm_dst->getPolyArray(dm_dst) : me_dst->mpoly;
+			const int num_polys_dst = dm_dst ? dm_dst->getNumPolys(dm_dst) : me_dst->totpoly;
+			MLoop *loops_dst = dm_dst ? dm_dst->getLoopArray(dm_dst) : me_dst->mloop;
+			const int num_loops_dst = dm_dst ? dm_dst->getNumLoops(dm_dst) : me_dst->totloop;
+			CustomData *pdata_dst = dm_dst ? dm_dst->getPolyDataLayout(dm_dst) : &me_dst->pdata;
+
+			if (!geom_map_init[PDATA]) {
+				if ((map_poly_mode == MREMAP_MODE_TOPOLOGY) && (num_polys_dst != dm_src->getNumPolys(dm_src))) {
+					BKE_report(reports, RPT_ERROR,
+					           "Source and destination meshes do not have the same amount of faces, "
+					           "'Topology' mapping cannot be used in this case");
+					return changed;
+				}
+				BKE_mesh_remap_calc_polys_from_dm(
+				        map_poly_mode, space_transform, max_distance, ray_radius,
+				        verts_dst, num_verts_dst, loops_dst, num_loops_dst,
+				        polys_dst, num_polys_dst, pdata_dst, dirty_nors_dst,
+				        dm_src, &geom_map[PDATA]);
+				geom_map_init[PDATA] = true;
+			}
+
+			if (mdef && vg_idx != -1 && !weights[PDATA]) {
+				weights[PDATA] = MEM_mallocN(sizeof(*weights[PDATA]) * (size_t)num_polys_dst, __func__);
+				BKE_defvert_extract_vgroup_to_polyweights(
+				        mdef, vg_idx, num_verts_dst, loops_dst, num_loops_dst,
+				        polys_dst, num_polys_dst, weights[PDATA], invert_vgroup);
+			}
+
+			if (data_transfer_layersmapping_generate(
+			        &lay_map, ob_src, ob_dst, dm_src, dm_dst, me_dst, ME_POLY,
+			        cddata_type, mix_mode, mix_factor, weights[PDATA],
+			        num_polys_dst, use_create, use_delete, fromlayers, tolayers))
+			{
+				CustomDataTransferLayerMap *lay_mapit;
+
+				changed = (lay_map.first != NULL);
+
+				for (lay_mapit = lay_map.first; lay_mapit; lay_mapit = lay_mapit->next) {
+					CustomData_data_transfer(&geom_map[PDATA], lay_mapit);
+				}
+
+				BLI_freelistN(&lay_map);
+			}
+		}
+	}
+
+	for (i = 0; i < DATAMAX; i++) {
+		BKE_mesh_remap_free(&geom_map[i]);
+		MEM_SAFE_FREE(weights[i]);
+	}
+
+	return changed;
+
+#undef VDATA
+#undef EDATA
+#undef LDATA
+#undef PDATA
+#undef DATAMAX
+}
+
+bool BKE_object_data_transfer_mesh(
+        Scene *scene, Object *ob_src, Object *ob_dst, const int data_types, const bool use_create,
+        const int map_vert_mode, const int map_edge_mode, const int map_loop_mode, const int map_poly_mode,
+        SpaceTransform *space_transform, const float max_distance, const float ray_radius,
+        const float islands_handling_precision,
+        const int fromlayers_select[DT_MULTILAYER_INDEX_MAX], const int tolayers_select[DT_MULTILAYER_INDEX_MAX],
+        const int mix_mode, const float mix_factor, const char *vgroup_name, const bool invert_vgroup,
+        ReportList *reports)
+{
+	return BKE_object_data_transfer_dm(
+	        scene, ob_src, ob_dst, NULL, data_types, use_create,
+	        map_vert_mode, map_edge_mode, map_loop_mode, map_poly_mode, space_transform,
+	        max_distance, ray_radius, islands_handling_precision, fromlayers_select, tolayers_select,
+	        mix_mode, mix_factor, vgroup_name, invert_vgroup, reports);
+}