Add weight preview to WeightVG modifiers, and first, simple/basic refactor of how modifiers can generate preview.

User side:
* Preview for DynamicPaint should keep the same behavior (for now). Weight preview should be somawhat quicker, though.
* Preview for WeightVG modifiers is only active in WeightPaint mode, and if the affected vgroup is the active one.
* Last active preview modifier in stack wins!

Note: that modifier preview topic is yet to be further refined, quite raw/incomplete for now.

Dev side:
* In draw code, renamed DRAW_DYNAMIC_PAINT_PREVIEW flag to DRAW_MODIFIERS_PREVIEW
* Removed use of MOD_DPAINT_PREVIEW_READY in DynamicPaint code (seems unecessary, and if it was, should be of more general scope).
* Added eModifierTypeFlag_UsesPreview to ModifierTypeFlag, for modifiers that can generate some preview data.
* Added three new modifier funcs, to handle preview modifiers in draw code / mod stack.
* For weights preview: added the generic DM_update_weight_mcol func, which can update WEIGHT_MCOL layer with either a given array of weights (currently used by DynamicPaint only), or from current active vgroup(s).

So now, draw code is fully generic (i.e. no more modifier-type checking in it). Mod stack code is generic to some extent, but will need more work.

1 files changed, 42 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/modifier.c b/source/blender/blenkernel/intern/modifier.c
index 5a389019519..911d303b4cf 100644
--- a/source/blender/blenkernel/intern/modifier.c
+++ b/source/blender/blenkernel/intern/modifier.c
@@ -142,6 +142,19 @@ int modifier_supportsMapping(ModifierData *md)
 			(mti->flags & eModifierTypeFlag_SupportsMapping));
 }
 
+int modifier_isPreview(ModifierData *md)
+{
+	ModifierTypeInfo *mti = modifierType_getInfo(md->type);
+
+	if (!(mti->flags & eModifierTypeFlag_UsesPreview))
+		return FALSE;
+
+	if (md->mode & eModifierMode_Realtime)
+		return TRUE;
+
+	return FALSE;
+}
+
 ModifierData *modifiers_findByType(Object *ob, ModifierType type)
 {
 	ModifierData *md = ob->modifiers.first;
@@ -385,6 +398,21 @@ LinkNode *modifiers_calcDataMasks(struct Scene *scene, Object *ob, ModifierData
 	return dataMasks;
 }
 
+ModifierData *modifiers_getLastPreview(struct Scene *scene, ModifierData *md, int required_mode)
+{
+	ModifierData *tmp_md = NULL;
+
+	if (required_mode != eModifierMode_Realtime)
+		return tmp_md;
+
+	/* Find the latest modifier in stack generating preview. */
+	for(; md; md = md->next) {
+		if(modifier_isEnabled(scene, md, required_mode) && modifier_isPreview(md))
+			tmp_md = md;
+	}
+	return tmp_md;
+}
+
 ModifierData *modifiers_getVirtualModifierList(Object *ob)
 {
 		/* Kinda hacky, but should be fine since we are never
@@ -545,6 +573,20 @@ int modifiers_isCorrectableDeformed(Object *ob)
 	return 0;
 }
 
+/* Check whether the given object has a modifier in its stack that uses WEIGHT_MCOL CD layer
+ * to preview something... Used by DynamicPaint and WeightVG currently. */
+int modifiers_isPreview(Object *ob)
+{
+	ModifierData *md = ob->modifiers.first;
+
+	for (; md; md = md->next) {
+		if (modifier_isPreview(md))
+			return TRUE;
+	}
+
+	return FALSE;
+}
+
 int modifiers_indexInObject(Object *ob, ModifierData *md_seek)
 {
 	int i= 0;