Sculpt: Cloth Snake Hook Brush

This implements Snake Hook as a deform type for the cloth brush. This
brush changes the strength of the deformation constraints per brush step
to avoid affecting the results of the simulation as much as possible. It
allows to grab the cloth without producing any artifacts in the surface
and create more natural looking folds than any of the other deformation
modes.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8621

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index b2794e9d9d6..dfc75e2fd54 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -259,6 +259,16 @@ typedef struct SculptPoseIKChain {
 
 /* Cloth Brush */
 
+typedef enum eSculptClothConstraintType {
+  /* Constraint that creates the structure of the cloth. */
+  SCULPT_CLOTH_CONSTRAINT_STRUCTURAL = 0,
+  /* Constraint that references the position of a vertex and a position in deformation_pos which
+     can be deformed by the tools. */
+  SCULPT_CLOTH_CONSTRAINT_DEFORMATION = 1,
+  /* Constarint that references the vertex position and its initial position. */
+  SCULPT_CLOTH_CONSTRAINT_SOFTBODY = 2,
+} eSculptClothConstraintType;
+
 typedef struct SculptClothLengthConstraint {
   /* Elements that are affected by the constraint. */
   /* Element a should always be a mesh vertex with the index stored in elem_index_a as it is always
@@ -274,6 +284,8 @@ typedef struct SculptClothLengthConstraint {
 
   float length;
   float strength;
+
+  eSculptClothConstraintType type;
 } SculptClothLengthConstraint;
 
 typedef struct SculptClothSimulation {
@@ -287,6 +299,7 @@ typedef struct SculptClothSimulation {
    * final positions of the simulated vertices are updated with constraints that use these points
    * as targets. */
   float (*deformation_pos)[3];
+  float *deformation_strength;
 
   float mass;
   float damping;