New Grease Pencil object for 2D animation

This commit merge the full development done in greasepencil-object branch and include mainly the following features.

- New grease pencil object.
- New drawing engine.
- New grease pencil modes Draw/Sculpt/Edit and Weight Paint.
- New brushes for grease pencil.
- New modifiers for grease pencil.
- New shaders FX.
- New material system (replace old palettes and colors).
- Split of annotations (old grease pencil) and new grease pencil object.
- UI adapted to blender 2.8.

You can get more info here:

https://code.blender.org/2017/12/drawing-2d-animation-in-blender-2-8/
https://code.blender.org/2018/07/grease-pencil-status-update/

This is the result of nearly two years of development and I want thanks firstly the other members of the grease pencil team: Daniel M. Lara, Matias Mendiola and Joshua Leung for their support, ideas and to keep working in the project all the time, without them this project had been impossible.

Also, I want thanks other Blender developers for their help, advices and to be there always to help me, and specially to Clément Foucault, Dalai Felinto, Pablo Vázquez and Campbell Barton.

1 files changed, 679 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/gpencil_modifier.c b/source/blender/blenkernel/intern/gpencil_modifier.c
new file mode 100644
index 00000000000..2ba738902a0
--- /dev/null
+++ b/source/blender/blenkernel/intern/gpencil_modifier.c
@@ -0,0 +1,679 @@
+/*
+ * ***** 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) 2017, Blender Foundation
+ * This is a new part of Blender
+ *
+ * Contributor(s): Antonio Vazquez
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/gpencil_modifier.c
+ *  \ingroup bke
+ */
+
+
+#include <stdio.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_blenlib.h"
+#include "BLI_utildefines.h"
+#include "BLI_math_vector.h"
+#include "BLI_string_utils.h"
+
+#include "BLT_translation.h"
+
+#include "DNA_meshdata_types.h"
+#include "DNA_scene_types.h"
+#include "DNA_object_types.h"
+#include "DNA_gpencil_types.h"
+#include "DNA_gpencil_modifier_types.h"
+
+#include "BKE_global.h"
+#include "BKE_library.h"
+#include "BKE_library_query.h"
+#include "BKE_gpencil.h"
+#include "BKE_lattice.h"
+#include "BKE_gpencil_modifier.h"
+#include "BKE_object.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_query.h"
+
+#include "MOD_gpencil_modifiertypes.h"
+
+static GpencilModifierTypeInfo *modifier_gpencil_types[NUM_GREASEPENCIL_MODIFIER_TYPES] = { NULL };
+
+/* *************************************************** */
+/* Geometry Utilities */
+
+/* calculate stroke normal using some points */
+void BKE_gpencil_stroke_normal(const bGPDstroke *gps, float r_normal[3])
+{
+	if (gps->totpoints < 3) {
+		zero_v3(r_normal);
+		return;
+	}
+
+	bGPDspoint *points = gps->points;
+	int totpoints = gps->totpoints;
+
+	const bGPDspoint *pt0 = &points[0];
+	const bGPDspoint *pt1 = &points[1];
+	const bGPDspoint *pt3 = &points[(int)(totpoints * 0.75)];
+
+	float vec1[3];
+	float vec2[3];
+
+	/* initial vector (p0 -> p1) */
+	sub_v3_v3v3(vec1, &pt1->x, &pt0->x);
+
+	/* point vector at 3/4 */
+	sub_v3_v3v3(vec2, &pt3->x, &pt0->x);
+
+	/* vector orthogonal to polygon plane */
+	cross_v3_v3v3(r_normal, vec1, vec2);
+
+	/* Normalize vector */
+	normalize_v3(r_normal);
+}
+
+/* Get points of stroke always flat to view not affected by camera view or view position */
+static void gpencil_stroke_project_2d(const bGPDspoint *points, int totpoints, vec2f *points2d)
+{
+	const bGPDspoint *pt0 = &points[0];
+	const bGPDspoint *pt1 = &points[1];
+	const bGPDspoint *pt3 = &points[(int)(totpoints * 0.75)];
+
+	float locx[3];
+	float locy[3];
+	float loc3[3];
+	float normal[3];
+
+	/* local X axis (p0 -> p1) */
+	sub_v3_v3v3(locx, &pt1->x, &pt0->x);
+
+	/* point vector at 3/4 */
+	sub_v3_v3v3(loc3, &pt3->x, &pt0->x);
+
+	/* vector orthogonal to polygon plane */
+	cross_v3_v3v3(normal, locx, loc3);
+
+	/* local Y axis (cross to normal/x axis) */
+	cross_v3_v3v3(locy, normal, locx);
+
+	/* Normalize vectors */
+	normalize_v3(locx);
+	normalize_v3(locy);
+
+	/* Get all points in local space */
+	for (int i = 0; i < totpoints; i++) {
+		const bGPDspoint *pt = &points[i];
+		float loc[3];
+
+		/* Get local space using first point as origin */
+		sub_v3_v3v3(loc, &pt->x, &pt0->x);
+
+		vec2f *point = &points2d[i];
+		point->x = dot_v3v3(loc, locx);
+		point->y = dot_v3v3(loc, locy);
+	}
+
+}
+
+/* Stroke Simplify ------------------------------------- */
+
+/* Reduce a series of points to a simplified version, but
+ * maintains the general shape of the series
+ *
+ * Ramer - Douglas - Peucker algorithm
+ * by http ://en.wikipedia.org/wiki/Ramer-Douglas-Peucker_algorithm
+ */
+static void gpencil_rdp_stroke(bGPDstroke *gps, vec2f *points2d, float epsilon)
+{
+	vec2f *old_points2d = points2d;
+	int totpoints = gps->totpoints;
+	char *marked = NULL;
+	char work;
+
+	int start = 1;
+	int end = gps->totpoints - 2;
+
+	marked = MEM_callocN(totpoints, "GP marked array");
+	marked[start] = 1;
+	marked[end] = 1;
+
+	work = 1;
+	int totmarked = 0;
+	/* while still reducing */
+	while (work) {
+		int ls, le;
+		work = 0;
+
+		ls = start;
+		le = start + 1;
+
+		/* while not over interval */
+		while (ls < end) {
+			int max_i = 0;
+			float v1[2];
+			/* divided to get more control */
+			float max_dist = epsilon / 10.0f;
+
+			/* find the next marked point */
+			while (marked[le] == 0) {
+				le++;
+			}
+
+			/* perpendicular vector to ls-le */
+			v1[1] = old_points2d[le].x - old_points2d[ls].x;
+			v1[0] = old_points2d[ls].y - old_points2d[le].y;
+
+			for (int i = ls + 1; i < le; i++) {
+				float mul;
+				float dist;
+				float v2[2];
+
+				v2[0] = old_points2d[i].x - old_points2d[ls].x;
+				v2[1] = old_points2d[i].y - old_points2d[ls].y;
+
+				if (v2[0] == 0 && v2[1] == 0) {
+					continue;
+				}
+
+				mul = (float)(v1[0] * v2[0] + v1[1] * v2[1]) / (float)(v2[0] * v2[0] + v2[1] * v2[1]);
+
+				dist = mul * mul * (v2[0] * v2[0] + v2[1] * v2[1]);
+
+				if (dist > max_dist) {
+					max_dist = dist;
+					max_i = i;
+				}
+			}
+
+			if (max_i != 0) {
+				work = 1;
+				marked[max_i] = 1;
+				totmarked++;
+			}
+
+			ls = le;
+			le = ls + 1;
+		}
+	}
+
+	/* adding points marked */
+	bGPDspoint *old_points = MEM_dupallocN(gps->points);
+	MDeformVert *old_dvert = MEM_dupallocN(gps->dvert);
+
+	/* resize gps */
+	gps->flag |= GP_STROKE_RECALC_CACHES;
+	gps->tot_triangles = 0;
+
+	int j = 0;
+	for (int i = 0; i < totpoints; i++) {
+		bGPDspoint *pt_src = &old_points[i];
+		bGPDspoint *pt = &gps->points[j];
+
+		MDeformVert *dvert_src = &old_dvert[i];
+		MDeformVert *dvert = &gps->dvert[j];
+
+		if ((marked[i]) || (i == 0) || (i == totpoints - 1)) {
+			memcpy(pt, pt_src, sizeof(bGPDspoint));
+			memcpy(dvert, dvert_src, sizeof(MDeformVert));
+			j++;
+		}
+		else {
+			BKE_gpencil_free_point_weights(dvert_src);
+		}
+	}
+
+	gps->totpoints = j;
+
+	MEM_SAFE_FREE(old_points);
+	MEM_SAFE_FREE(old_dvert);
+	MEM_SAFE_FREE(marked);
+}
+
+/* Simplify stroke using Ramer-Douglas-Peucker algorithm */
+void BKE_gpencil_simplify_stroke(bGPDstroke *gps, float factor)
+{
+	/* first create temp data and convert points to 2D */
+	vec2f *points2d = MEM_mallocN(sizeof(vec2f) * gps->totpoints, "GP Stroke temp 2d points");
+
+	gpencil_stroke_project_2d(gps->points, gps->totpoints, points2d);
+
+	gpencil_rdp_stroke(gps, points2d, factor);
+
+	MEM_SAFE_FREE(points2d);
+}
+
+/* Simplify alternate vertex of stroke except extrems */
+void BKE_gpencil_simplify_fixed(bGPDstroke *gps)
+{
+	if (gps->totpoints < 5) {
+		return;
+	}
+
+	/* save points */
+	bGPDspoint *old_points = MEM_dupallocN(gps->points);
+	MDeformVert *old_dvert = MEM_dupallocN(gps->dvert);
+
+	/* resize gps */
+	int newtot = (gps->totpoints - 2) / 2;
+	if (((gps->totpoints - 2) % 2) > 0) {
+		newtot++;
+	}
+	newtot += 2;
+
+	gps->points = MEM_recallocN(gps->points, sizeof(*gps->points) * newtot);
+	gps->dvert = MEM_recallocN(gps->dvert, sizeof(*gps->dvert) * newtot);
+	gps->flag |= GP_STROKE_RECALC_CACHES;
+	gps->tot_triangles = 0;
+
+	int j = 0;
+	for (int i = 0; i < gps->totpoints; i++) {
+		bGPDspoint *pt_src = &old_points[i];
+		bGPDspoint *pt = &gps->points[j];
+
+		MDeformVert *dvert_src = &old_dvert[i];
+		MDeformVert *dvert = &gps->dvert[j];
+
+		if ((i == 0) || (i == gps->totpoints - 1) || ((i % 2) > 0.0)) {
+			memcpy(pt, pt_src, sizeof(bGPDspoint));
+			memcpy(dvert, dvert_src, sizeof(MDeformVert));
+			j++;
+		}
+		else {
+			BKE_gpencil_free_point_weights(dvert_src);
+		}
+	}
+
+	gps->totpoints = j;
+
+	MEM_SAFE_FREE(old_points);
+	MEM_SAFE_FREE(old_dvert);
+}
+
+/* *************************************************** */
+/* Modifier Utilities */
+
+/* Lattice Modifier ---------------------------------- */
+/* Usually, evaluation of the lattice modifier is self-contained.
+ * However, since GP's modifiers operate on a per-stroke basis,
+ * we need to these two extra functions that called before/after
+ * each loop over all the geometry being evaluated.
+ */
+
+/* init lattice deform data */
+void BKE_gpencil_lattice_init(Object *ob)
+{
+	GpencilModifierData *md;
+	for (md = ob->greasepencil_modifiers.first; md; md = md->next) {
+		if (md->type == eGpencilModifierType_Lattice) {
+			LatticeGpencilModifierData *mmd = (LatticeGpencilModifierData *)md;
+			Object *latob = NULL;
+
+			latob = mmd->object;
+			if ((!latob) || (latob->type != OB_LATTICE)) {
+				return;
+			}
+			if (mmd->cache_data) {
+				end_latt_deform((struct LatticeDeformData *)mmd->cache_data);
+			}
+
+			/* init deform data */
+			mmd->cache_data = (struct LatticeDeformData *)init_latt_deform(latob, ob);
+		}
+	}
+}
+
+/* clear lattice deform data */
+void BKE_gpencil_lattice_clear(Object *ob)
+{
+	GpencilModifierData *md;
+	for (md = ob->greasepencil_modifiers.first; md; md = md->next) {
+		if (md->type == eGpencilModifierType_Lattice) {
+			LatticeGpencilModifierData *mmd = (LatticeGpencilModifierData *)md;
+			if ((mmd) && (mmd->cache_data)) {
+				end_latt_deform((struct LatticeDeformData *)mmd->cache_data);
+				mmd->cache_data = NULL;
+			}
+		}
+	}
+}
+
+/* *************************************************** */
+/* Modifier Methods - Evaluation Loops, etc. */
+
+/* check if exist geometry modifiers */
+bool BKE_gpencil_has_geometry_modifiers(Object *ob)
+{
+	GpencilModifierData *md;
+	for (md = ob->greasepencil_modifiers.first; md; md = md->next) {
+		const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+		if (mti && mti->generateStrokes) {
+			return true;
+		}
+	}
+	return false;
+}
+
+/* apply stroke modifiers */
+void BKE_gpencil_stroke_modifiers(Depsgraph *depsgraph, Object *ob, bGPDlayer *gpl, bGPDframe *UNUSED(gpf), bGPDstroke *gps, bool is_render)
+{
+	GpencilModifierData *md;
+	bGPdata *gpd = ob->data;
+	const bool is_edit = GPENCIL_ANY_EDIT_MODE(gpd);
+
+	for (md = ob->greasepencil_modifiers.first; md; md = md->next) {
+		if (GPENCIL_MODIFIER_ACTIVE(md, is_render))
+		{
+			const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+			if (GPENCIL_MODIFIER_EDIT(md, is_edit)) {
+				continue;
+			}
+
+			if (mti && mti->deformStroke) {
+				mti->deformStroke(md, depsgraph, ob, gpl, gps);
+			}
+		}
+	}
+}
+
+/* apply stroke geometry modifiers */
+void BKE_gpencil_geometry_modifiers(Depsgraph *depsgraph, Object *ob, bGPDlayer *gpl, bGPDframe *gpf, bool is_render)
+{
+	GpencilModifierData *md;
+	bGPdata *gpd = ob->data;
+	const bool is_edit = GPENCIL_ANY_EDIT_MODE(gpd);
+
+	for (md = ob->greasepencil_modifiers.first; md; md = md->next) {
+		if (GPENCIL_MODIFIER_ACTIVE(md, is_render))
+		{
+			const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+			if (GPENCIL_MODIFIER_EDIT(md, is_edit)) {
+				continue;
+			}
+
+			if (mti->generateStrokes) {
+				mti->generateStrokes(md, depsgraph, ob, gpl, gpf);
+			}
+		}
+	}
+}
+
+/* *************************************************** */
+
+void BKE_gpencil_eval_geometry(Depsgraph *depsgraph,
+                               bGPdata *gpd)
+{
+	DEG_debug_print_eval(depsgraph, __func__, gpd->id.name, gpd);
+	int ctime = (int)DEG_get_ctime(depsgraph);
+
+	/* update active frame */
+	for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
+		gpl->actframe = BKE_gpencil_layer_getframe(gpl, ctime, GP_GETFRAME_USE_PREV);
+	}
+
+	/* TODO: Move "derived_gpf" logic here from DRW_gpencil_populate_datablock()?
+	 * This would be better than inventing our own logic for this stuff...
+	 */
+
+	/* TODO: Move the following code to "BKE_gpencil_eval_done()" (marked as an exit node)
+	 * later when there's more happening here. For now, let's just keep this in here to avoid
+	 * needing to have one more node slowing down evaluation...
+	 */
+	if (DEG_is_active(depsgraph)) {
+		bGPdata *gpd_orig = (bGPdata *)DEG_get_original_id(&gpd->id);
+
+		/* sync "actframe" changes back to main-db too,
+		 * so that editing tools work with copy-on-write
+		 * when the current frame changes
+		 */
+		for (bGPDlayer *gpl = gpd_orig->layers.first; gpl; gpl = gpl->next) {
+			gpl->actframe = BKE_gpencil_layer_getframe(gpl, ctime, GP_GETFRAME_USE_PREV);
+		}
+	}
+}
+
+void BKE_gpencil_modifier_init(void)
+{
+	/* Initialize modifier types */
+	gpencil_modifier_type_init(modifier_gpencil_types); /* MOD_gpencil_util.c */
+}
+
+GpencilModifierData *BKE_gpencil_modifier_new(int type)
+{
+	const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(type);
+	GpencilModifierData *md = MEM_callocN(mti->struct_size, mti->struct_name);
+
+	/* note, this name must be made unique later */
+	BLI_strncpy(md->name, DATA_(mti->name), sizeof(md->name));
+
+	md->type = type;
+	md->mode = eGpencilModifierMode_Realtime | eGpencilModifierMode_Render | eGpencilModifierMode_Expanded;
+	md->flag = eGpencilModifierFlag_StaticOverride_Local;
+
+	if (mti->flags & eGpencilModifierTypeFlag_EnableInEditmode)
+		md->mode |= eGpencilModifierMode_Editmode;
+
+	if (mti->initData) mti->initData(md);
+
+	return md;
+}
+
+static void modifier_free_data_id_us_cb(void *UNUSED(userData), Object *UNUSED(ob), ID **idpoin, int cb_flag)
+{
+	ID *id = *idpoin;
+	if (id != NULL && (cb_flag & IDWALK_CB_USER) != 0) {
+		id_us_min(id);
+	}
+}
+
+void BKE_gpencil_modifier_free_ex(GpencilModifierData *md, const int flag)
+{
+	const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+	if ((flag & LIB_ID_CREATE_NO_USER_REFCOUNT) == 0) {
+		if (mti->foreachIDLink) {
+			mti->foreachIDLink(md, NULL, modifier_free_data_id_us_cb, NULL);
+		}
+		else if (mti->foreachObjectLink) {
+			mti->foreachObjectLink(md, NULL, (GreasePencilObjectWalkFunc)modifier_free_data_id_us_cb, NULL);
+		}
+	}
+
+	if (mti->freeData) mti->freeData(md);
+	if (md->error) MEM_freeN(md->error);
+
+	MEM_freeN(md);
+}
+
+void BKE_gpencil_modifier_free(GpencilModifierData *md)
+{
+	BKE_gpencil_modifier_free_ex(md, 0);
+}
+
+/* check unique name */
+bool BKE_gpencil_modifier_unique_name(ListBase *modifiers, GpencilModifierData *gmd)
+{
+	if (modifiers && gmd) {
+		const GpencilModifierTypeInfo *gmti = BKE_gpencil_modifierType_getInfo(gmd->type);
+		return BLI_uniquename(modifiers, gmd, DATA_(gmti->name), '.', offsetof(GpencilModifierData, name), sizeof(gmd->name));
+	}
+	return false;
+}
+
+bool BKE_gpencil_modifier_dependsOnTime(GpencilModifierData *md)
+{
+	const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+	return mti->dependsOnTime && mti->dependsOnTime(md);
+}
+
+const GpencilModifierTypeInfo *BKE_gpencil_modifierType_getInfo(GpencilModifierType type)
+{
+	/* type unsigned, no need to check < 0 */
+	if (type < NUM_GREASEPENCIL_MODIFIER_TYPES && modifier_gpencil_types[type]->name[0] != '\0') {
+		return modifier_gpencil_types[type];
+	}
+	else {
+		return NULL;
+	}
+}
+
+void BKE_gpencil_modifier_copyData_generic(const GpencilModifierData *md_src, GpencilModifierData *md_dst)
+{
+	const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md_src->type);
+
+	/* md_dst may have alredy be fully initialized with some extra allocated data,
+	* we need to free it now to avoid memleak. */
+	if (mti->freeData) {
+		mti->freeData(md_dst);
+	}
+
+	const size_t data_size = sizeof(GpencilModifierData);
+	const char *md_src_data = ((const char *)md_src) + data_size;
+	char       *md_dst_data = ((char *)md_dst) + data_size;
+	BLI_assert(data_size <= (size_t)mti->struct_size);
+	memcpy(md_dst_data, md_src_data, (size_t)mti->struct_size - data_size);
+}
+
+static void gpencil_modifier_copy_data_id_us_cb(void *UNUSED(userData), Object *UNUSED(ob), ID **idpoin, int cb_flag)
+{
+	ID *id = *idpoin;
+	if (id != NULL && (cb_flag & IDWALK_CB_USER) != 0) {
+		id_us_plus(id);
+	}
+}
+
+void BKE_gpencil_modifier_copyData_ex(GpencilModifierData *md, GpencilModifierData *target, const int flag)
+{
+	const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+	target->mode = md->mode;
+	target->flag = md->flag;
+
+	if (mti->copyData) {
+		mti->copyData(md, target);
+	}
+
+	if ((flag & LIB_ID_CREATE_NO_USER_REFCOUNT) == 0) {
+		if (mti->foreachIDLink) {
+			mti->foreachIDLink(target, NULL, gpencil_modifier_copy_data_id_us_cb, NULL);
+		}
+		else if (mti->foreachObjectLink) {
+			mti->foreachObjectLink(target, NULL, (GreasePencilObjectWalkFunc)gpencil_modifier_copy_data_id_us_cb, NULL);
+		}
+	}
+}
+
+void BKE_gpencil_modifier_copyData(GpencilModifierData *md, GpencilModifierData *target)
+{
+	BKE_gpencil_modifier_copyData_ex(md, target, 0);
+}
+
+GpencilModifierData *BKE_gpencil_modifiers_findByType(Object *ob, GpencilModifierType type)
+{
+	GpencilModifierData *md = ob->greasepencil_modifiers.first;
+
+	for (; md; md = md->next)
+		if (md->type == type)
+			break;
+
+	return md;
+}
+
+void BKE_gpencil_modifiers_foreachIDLink(Object *ob, GreasePencilIDWalkFunc walk, void *userData)
+{
+	GpencilModifierData *md = ob->greasepencil_modifiers.first;
+
+	for (; md; md = md->next) {
+		const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+		if (mti->foreachIDLink) mti->foreachIDLink(md, ob, walk, userData);
+		else if (mti->foreachObjectLink) {
+			/* each Object can masquerade as an ID, so this should be OK */
+			GreasePencilObjectWalkFunc fp = (GreasePencilObjectWalkFunc)walk;
+			mti->foreachObjectLink(md, ob, fp, userData);
+		}
+	}
+}
+
+void BKE_gpencil_modifiers_foreachTexLink(Object *ob, GreasePencilTexWalkFunc walk, void *userData)
+{
+	GpencilModifierData *md = ob->greasepencil_modifiers.first;
+
+	for (; md; md = md->next) {
+		const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+
+		if (mti->foreachTexLink)
+			mti->foreachTexLink(md, ob, walk, userData);
+	}
+}
+
+GpencilModifierData *BKE_gpencil_modifiers_findByName(Object *ob, const char *name)
+{
+	return BLI_findstring(&(ob->greasepencil_modifiers), name, offsetof(GpencilModifierData, name));
+}
+
+/* helper function for per-instance positioning */
+void BKE_gpencil_instance_modifier_instance_tfm(InstanceGpencilModifierData *mmd, const int elem_idx[3], float r_mat[4][4])
+{
+	float offset[3], rot[3], scale[3];
+	int ri = mmd->rnd[0];
+	float factor;
+
+	offset[0] = mmd->offset[0] * elem_idx[0];
+	offset[1] = mmd->offset[1] * elem_idx[1];
+	offset[2] = mmd->offset[2] * elem_idx[2];
+
+	/* rotation */
+	if (mmd->flag & GP_INSTANCE_RANDOM_ROT) {
+		factor = mmd->rnd_rot * mmd->rnd[ri];
+		mul_v3_v3fl(rot, mmd->rot, factor);
+		add_v3_v3(rot, mmd->rot);
+	}
+	else {
+		copy_v3_v3(rot, mmd->rot);
+	}
+
+	/* scale */
+	if (mmd->flag & GP_INSTANCE_RANDOM_SIZE) {
+		factor = mmd->rnd_size * mmd->rnd[ri];
+		mul_v3_v3fl(scale, mmd->scale, factor);
+		add_v3_v3(scale, mmd->scale);
+	}
+	else {
+		copy_v3_v3(scale, mmd->scale);
+	}
+
+	/* advance random index */
+	mmd->rnd[0]++;
+	if (mmd->rnd[0] > 19) {
+		mmd->rnd[0] = 1;
+	}
+
+	/* calculate matrix */
+	loc_eul_size_to_mat4(r_mat, offset, rot, scale);
+}