Sculpt: Enable Cloth Simulation Target for Pose and Boundary

This adds a new brush property called "Deformation Target" which
controls how the brush deformations is going to affect the mesh data. By
default is set to Geometry, which makes the brushes displace the
vertices. When set to Cloth Simulation, the deformation of the brush is
applied to the cloth solver constraints, so the simulation is
responsible to apply the final deformation. This allows to add cloth
simulation effects to other sculpt tools with minor modifications to their
code.

This patch enables Cloth Simulation deformation target for Pose and
Boundary brushes, which are tools that are already designed to work in
low poly counts and produce large deformations. This allows creating the
most common cloth effects, like bending and compressing folds, without
relying on collisions.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8578

1 files changed, 13 insertions, 2 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_intern.h b/source/blender/editors/sculpt_paint/sculpt_intern.h
index df81deeb9d4..548ef00ad87 100644
--- a/source/blender/editors/sculpt_paint/sculpt_intern.h
+++ b/source/blender/editors/sculpt_paint/sculpt_intern.h
@@ -104,6 +104,12 @@ void SCULPT_vertex_persistent_normal_get(SculptSession *ss, int index, float no[
  * current coordinate of the vertex. */
 void SCULPT_vertex_limit_surface_get(SculptSession *ss, int index, float r_co[3]);
 
+/* Returns the pointer to the coordinates that should be edited from a brush tool iterator
+ * depending on the given deformation target. */
+float *SCULPT_brush_deform_target_vertex_co_get(SculptSession *ss,
+                                                const int deform_target,
+                                                PBVHVertexIter *iter);
+
 #define SCULPT_VERTEX_NEIGHBOR_FIXED_CAPACITY 256
 typedef struct SculptVertexNeighborIter {
   /* Storage */
@@ -350,6 +356,7 @@ void SCULPT_do_cloth_brush(struct Sculpt *sd,
                            struct Object *ob,
                            struct PBVHNode **nodes,
                            int totnode);
+
 void SCULPT_cloth_simulation_free(struct SculptClothSimulation *cloth_sim);
 
 struct SculptClothSimulation *SCULPT_cloth_brush_simulation_create(struct SculptSession *ss,
@@ -391,8 +398,12 @@ void SCULPT_cloth_plane_falloff_preview_draw(const uint gpuattr,
 
 BLI_INLINE bool SCULPT_is_cloth_deform_brush(const Brush *brush)
 {
-  return brush->sculpt_tool == SCULPT_TOOL_CLOTH &&
-         brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_GRAB;
+  return (brush->sculpt_tool == SCULPT_TOOL_CLOTH &&
+          brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_GRAB) ||
+         /* All brushes that are not the cloth brush deform the simulation using softbody
+            constriants instead of applying forces. */
+         (brush->sculpt_tool != SCULPT_TOOL_CLOTH &&
+          brush->deform_target == BRUSH_DEFORM_TARGET_CLOTH_SIM);
 }
 
 /* Pose Brush. */