MOD_curve: do not compute mesh when not needed.

This modifier only uses mesh to get vgroup, which is only needed in case
modified object is indeed a mesh! Building a mesh from curve here is not
only useless and time-consuming, it will also easily fail the assert
about same number of vertices!

Also, use MOD_get_vgroup() helper in modifier code itself and pass
reluting MDeformVert & index to BKE_curve's curve_deform_verts(),
this is simpler and avoids duplicating vgroup handling code.

Also fixes crash when used on lattice.

Related to T57972.

1 files changed, 2 insertions, 3 deletions

diff --git a/source/blender/blenkernel/BKE_lattice.h b/source/blender/blenkernel/BKE_lattice.h
index 2e093ba11a2..b2911129525 100644
--- a/source/blender/blenkernel/BKE_lattice.h
+++ b/source/blender/blenkernel/BKE_lattice.h
@@ -63,9 +63,8 @@ bool object_deform_mball(struct Object *ob, struct ListBase *dispbase);
 void outside_lattice(struct Lattice *lt);
 
 void curve_deform_verts(
-        struct Object *cuOb, struct Object *target,
-        struct Mesh *mesh, float (*vertexCos)[3],
-        int numVerts, const char *vgroup, short defaxis);
+        struct Object *cuOb, struct Object *target, float (*vertexCos)[3],
+        int numVerts, struct MDeformVert *dvert, const int defgrp_index, short defaxis);
 void curve_deform_vector(
         struct Object *cuOb, struct Object *target,
         float orco[3], float vec[3], float mat[3][3], int no_rot_axis);