Sculpt: Use constraints in cloth deform brushes

Previously, deform brushes were modifying the final positions in the
simulation directly, which was causing all sorts of artifacts in the
deformed area and problems with other features of the solver.
Now these brushes deform a separate array of positions and the solver
adds constraints to them, so the real vertices are moved when solving
the constraints. This prevents those artifacts and gives the brush a
much better behavior.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8424

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index a84fb258330..382919147f8 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -283,6 +283,11 @@ typedef struct SculptClothSimulation {
   int capacity_length_constraints;
   float *length_constraint_tweak;
 
+  /* Position anchors for deformation brushes. These positions are modified by the brush and the
+   * final positions of the simulated vertices are updated with constraints that use these points
+   * as targets. */
+  float (*deformation_pos)[3];
+
   float mass;
   float damping;