Fix modifiers evaluation outside of depsgraph/CoW context.

Fix T58237: Exporters: Curve Modifier not applied when "apply modifiers" are selected.
Fix T58856: Python: "to_mesh" broken in 2.8.

...And many other cases... ;)

Thing is, we need target IDs to always be evaluated ones (at least I
cannot see any case where having orig ones is desired effect here).
Depsgraph/Cow system ensures us that when modifiers are evaluated by it,
but they can also be called outside of this context, e.g. when doing
binding, or object conversion...

So we need to ensure in modifiers code that we actually are always
working with eval data for those targets.

Note that I did not touch to physics modifiers, those are a bit touchy
and rather not 'fix' something there until proven broken!

1 files changed, 8 insertions, 5 deletions

diff --git a/source/blender/modifiers/intern/MOD_simpledeform.c b/source/blender/modifiers/intern/MOD_simpledeform.c
index f1ad93e7182..33a585e5324 100644
--- a/source/blender/modifiers/intern/MOD_simpledeform.c
+++ b/source/blender/modifiers/intern/MOD_simpledeform.c
@@ -46,6 +46,8 @@
 #include "BKE_modifier.h"
 #include "BKE_deform.h"
 
+#include "DEG_depsgraph_query.h"
+
 #include "MOD_util.h"
 
 #include "bmesh.h"
@@ -186,7 +188,8 @@ static void simpleDeform_bend(const float factor, const int axis, const float dc
 
 /* simple deform modifier */
 static void SimpleDeformModifier_do(
-        SimpleDeformModifierData *smd, struct Object *ob, struct Mesh *mesh,
+        SimpleDeformModifierData *smd, const ModifierEvalContext *ctx,
+        struct Object *ob, struct Mesh *mesh,
         float (*vertexCos)[3], int numVerts)
 {
 	const float base_limit[2] = {0.0f, 0.0f};
@@ -227,9 +230,9 @@ static void SimpleDeformModifier_do(
 	smd->limit[0] = min_ff(smd->limit[0], smd->limit[1]);  /* Upper limit >= than lower limit */
 
 	/* Calculate matrixs do convert between coordinate spaces */
-	if (smd->origin) {
+	if (smd->origin != NULL) {
 		transf = &tmp_transf;
-		BLI_SPACE_TRANSFORM_SETUP(transf, ob, smd->origin);
+		BLI_SPACE_TRANSFORM_SETUP(transf, ob, DEG_get_evaluated_object(ctx->depsgraph, smd->origin));
 	}
 
 	/* Update limits if needed */
@@ -394,7 +397,7 @@ static void deformVerts(
 		mesh_src = MOD_deform_mesh_eval_get(ctx->object, NULL, mesh, NULL, numVerts, false, false);
 	}
 
-	SimpleDeformModifier_do(sdmd, ctx->object, mesh_src, vertexCos, numVerts);
+	SimpleDeformModifier_do(sdmd, ctx, ctx->object, mesh_src, vertexCos, numVerts);
 
 	if (!ELEM(mesh_src, NULL, mesh)) {
 		BKE_id_free(NULL, mesh_src);
@@ -416,7 +419,7 @@ static void deformVertsEM(
 		mesh_src = MOD_deform_mesh_eval_get(ctx->object, editData, mesh, NULL, numVerts, false, false);
 	}
 
-	SimpleDeformModifier_do(sdmd, ctx->object, mesh_src, vertexCos, numVerts);
+	SimpleDeformModifier_do(sdmd, ctx, ctx->object, mesh_src, vertexCos, numVerts);
 
 	if (!ELEM(mesh_src, NULL, mesh)) {
 		BKE_id_free(NULL, mesh_src);