GP: New Armature modifier and tools to handle weights

This commit adds a new armature modifier for grease pencil. The deformations are done reusing the mesh deform routines.

There is also a new operator in weight paint mode to help the artist to generate weights base on armatures. This operator is required because 2D animation workflow is not equal to meshes when parent an object to armatures.

In the drawing engine has been added the option to handle the Fade object parameter used in armatures to see the strokes while move the bones.

When rename bones, all related data of grease pencil is renamed too. This not only affect new armature code, but also layers parented and hook modifiers.

Thanks @aligorith for his review and help.

1 files changed, 205 insertions, 0 deletions

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c b/source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c
new file mode 100644
index 00000000000..4ae48e73d0f
--- /dev/null
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencilarmature.c
@@ -0,0 +1,205 @@
+/*
+ * ***** 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) 2018, Blender Foundation
+ * This is a new part of Blender
+ *
+ * Contributor(s): Antonio Vazquez
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ *
+ */
+
+/** \file blender/gpencil_modifiers/intern/MOD_gpencilarmature.c
+ *  \ingroup modifiers
+ */
+
+#include <stdio.h>
+
+#include "DNA_armature_types.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 "DNA_modifier_types.h"
+#include "BLI_math.h"
+
+#include "BLI_listbase.h"
+#include "BLI_task.h"
+#include "BLI_utildefines.h"
+
+#include "BKE_lattice.h"
+#include "BKE_context.h"
+#include "BKE_gpencil.h"
+#include "BKE_gpencil_modifier.h"
+#include "BKE_modifier.h"
+#include "BKE_library_query.h"
+#include "BKE_scene.h"
+#include "BKE_main.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "MOD_gpencil_util.h"
+#include "MOD_gpencil_modifiertypes.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_build.h"
+#include "DEG_depsgraph_query.h"
+
+static void initData(GpencilModifierData *md)
+{
+	ArmatureGpencilModifierData *gpmd = (ArmatureGpencilModifierData *)md;
+	gpmd->object = NULL;
+	gpmd->deformflag = ARM_DEF_VGROUP;
+}
+
+static void copyData(const GpencilModifierData *md, GpencilModifierData *target)
+{
+	BKE_gpencil_modifier_copyData_generic(md, target);
+}
+
+static void gpencil_deform_verts(
+	ArmatureGpencilModifierData *mmd, Object *target,
+	bGPDstroke *gps)
+{
+	bGPDspoint *pt = gps->points;
+	float *all_vert_coords = MEM_callocN(sizeof(float) * 3 * gps->totpoints, __func__);
+	int i;
+
+	BKE_gpencil_dvert_ensure(gps);
+
+	/* prepare array of points */
+	for (i = 0; i < gps->totpoints; i++, pt++) {
+		float *pt_coords = &all_vert_coords[3 * i];
+		float co[3];
+		copy_v3_v3(co, &pt->x);
+		copy_v3_v3(pt_coords, co);
+	}
+
+	/* deform verts */
+	armature_deform_verts(mmd->object, target, NULL,
+						(float(*)[3])all_vert_coords,
+						NULL, gps->totpoints,
+						mmd->deformflag,
+						(float(*)[3])mmd->prevCos,
+						mmd->vgname, gps);
+
+	/* Apply deformed coordinates */
+	pt = gps->points;
+	for (i = 0; i < gps->totpoints; i++, pt++) {
+		float *pt_coords = &all_vert_coords[3 * i];
+		copy_v3_v3(&pt->x, pt_coords);
+	}
+
+	MEM_SAFE_FREE(all_vert_coords);
+
+}
+
+/* deform stroke */
+static void deformStroke(
+        GpencilModifierData *md, Depsgraph *UNUSED(depsgraph),
+        Object *ob, bGPDlayer *UNUSED(gpl), bGPDstroke *gps)
+{
+	ArmatureGpencilModifierData *mmd = (ArmatureGpencilModifierData *)md;
+	if (!mmd->object) {
+		return;
+	}
+
+	gpencil_deform_verts(mmd, ob, gps);
+}
+
+static void bakeModifier(
+        Main *bmain, Depsgraph *depsgraph,
+        GpencilModifierData *md, Object *ob)
+{
+	ArmatureGpencilModifierData *mmd = (ArmatureGpencilModifierData *)md;
+	Scene *scene = DEG_get_evaluated_scene(depsgraph);
+	bGPdata *gpd = ob->data;
+	int oldframe = (int)DEG_get_ctime(depsgraph);
+
+	if (mmd->object == NULL)
+		return;
+
+	for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
+		for (bGPDframe *gpf = gpl->frames.first; gpf; gpf = gpf->next) {
+			/* apply armature effects on this frame
+			 * NOTE: this assumes that we don't want armature animation on non-keyframed frames
+			 */
+			CFRA = gpf->framenum;
+			BKE_scene_graph_update_for_newframe(depsgraph, bmain);
+
+			/* compute armature effects on this frame */
+			for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
+				deformStroke(md, depsgraph, ob, gpl, gps);
+			}
+		}
+	}
+
+	/* return frame state and DB to original state */
+	CFRA = oldframe;
+	BKE_scene_graph_update_for_newframe(depsgraph, bmain);
+}
+
+static bool isDisabled(GpencilModifierData *md, int UNUSED(userRenderParams))
+{
+	ArmatureGpencilModifierData *mmd = (ArmatureGpencilModifierData *)md;
+
+	return !mmd->object;
+}
+
+static void updateDepsgraph(GpencilModifierData *md, const ModifierUpdateDepsgraphContext *ctx)
+{
+	ArmatureGpencilModifierData *lmd = (ArmatureGpencilModifierData *)md;
+	if (lmd->object != NULL) {
+		DEG_add_object_relation(ctx->node, lmd->object, DEG_OB_COMP_EVAL_POSE, "Armature Modifier");
+		DEG_add_object_relation(ctx->node, lmd->object, DEG_OB_COMP_TRANSFORM, "Armature Modifier");
+	}
+	DEG_add_object_relation(ctx->node, ctx->object, DEG_OB_COMP_TRANSFORM, "Armature Modifier");
+}
+
+static void foreachObjectLink(
+        GpencilModifierData *md, Object *ob,
+        ObjectWalkFunc walk, void *userData)
+{
+	ArmatureGpencilModifierData *mmd = (ArmatureGpencilModifierData *)md;
+
+	walk(userData, ob, &mmd->object, IDWALK_CB_NOP);
+}
+
+GpencilModifierTypeInfo modifierType_Gpencil_Armature = {
+	/* name */              "Armature",
+	/* structName */        "ArmatureGpencilModifierData",
+	/* structSize */        sizeof(ArmatureGpencilModifierData),
+	/* type */              eGpencilModifierTypeType_Gpencil,
+	/* flags */             0,
+
+	/* copyData */          copyData,
+
+	/* deformStroke */      deformStroke,
+	/* generateStrokes */   NULL,
+	/* bakeModifier */      bakeModifier,
+
+	/* initData */          initData,
+	/* freeData */          NULL,
+	/* isDisabled */        isDisabled,
+	/* updateDepsgraph */   updateDepsgraph,
+	/* dependsOnTime */     NULL,
+	/* foreachObjectLink */ foreachObjectLink,
+	/* foreachIDLink */     NULL,
+	/* foreachTexLink */    NULL,
+};