Shrinkwrap: implement the use of smooth normals in constraint & modifier.

- Use smooth normals to displace in Above Surface mode.
- Add an option to align an axis to the normal in the constraint.

I've seen people request the alignment feature, and it seems useful.
For the actual aligning I use the damped track logic.

In order to conveniently keep mesh data needed for normal
computation together, a new data structure is introduced.

Reviewers: mont29

Differential Revision: https://developer.blender.org/D3762

1 files changed, 8 insertions, 2 deletions

diff --git a/source/blender/modifiers/intern/MOD_shrinkwrap.c b/source/blender/modifiers/intern/MOD_shrinkwrap.c
index 7864e888a48..4ba33461bbd 100644
--- a/source/blender/modifiers/intern/MOD_shrinkwrap.c
+++ b/source/blender/modifiers/intern/MOD_shrinkwrap.c
@@ -141,13 +141,19 @@ static void deformVertsEM(
 static void updateDepsgraph(ModifierData *md, const ModifierUpdateDepsgraphContext *ctx)
 {
 	ShrinkwrapModifierData *smd = (ShrinkwrapModifierData *)md;
+	CustomDataMask mask = 0;
+
+	if (BKE_shrinkwrap_needs_normals(smd->shrinkType, smd->shrinkMode)) {
+		mask |= CD_MASK_NORMAL | CD_MASK_CUSTOMLOOPNORMAL;
+	}
+
 	if (smd->target != NULL) {
 		DEG_add_object_relation(ctx->node, smd->target, DEG_OB_COMP_TRANSFORM, "Shrinkwrap Modifier");
-		DEG_add_object_relation(ctx->node, smd->target, DEG_OB_COMP_GEOMETRY, "Shrinkwrap Modifier");
+		DEG_add_object_customdata_relation(ctx->node, smd->target, DEG_OB_COMP_GEOMETRY, mask, "Shrinkwrap Modifier");
 	}
 	if (smd->auxTarget != NULL) {
 		DEG_add_object_relation(ctx->node, smd->auxTarget, DEG_OB_COMP_TRANSFORM, "Shrinkwrap Modifier");
-		DEG_add_object_relation(ctx->node, smd->auxTarget, DEG_OB_COMP_GEOMETRY, "Shrinkwrap Modifier");
+		DEG_add_object_customdata_relation(ctx->node, smd->auxTarget, DEG_OB_COMP_GEOMETRY, mask, "Shrinkwrap Modifier");
 	}
 	DEG_add_object_relation(ctx->node, ctx->object, DEG_OB_COMP_TRANSFORM, "Shrinkwrap Modifier");
 }