Sculpt: Elastic deform type for Snake Hook

This adds deformation types to snake hook and the elastic deformation
type. This mode deforms the mesh using a kelvinlet instead of applying
the displacement directly inside the brush radius, which is great for
stylized shapes sketching.

Changes in rake rotation when using elastic are too strong when set
to 1, so I'll add a nicer way to support rake rotations with smoother
transitions in the future.

Reviewed By: sergey, JulienKaspar

Differential Revision: https://developer.blender.org/D9560

1 files changed, 9 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_brush_types.h b/source/blender/makesdna/DNA_brush_types.h
index 50aac69da19..7bd3c7d0117 100644
--- a/source/blender/makesdna/DNA_brush_types.h
+++ b/source/blender/makesdna/DNA_brush_types.h
@@ -402,6 +402,11 @@ typedef enum eBrushBoundaryFalloffType {
   BRUSH_BOUNDARY_FALLOFF_LOOP_INVERT = 3,
 } eBrushBoundaryFalloffType;
 
+typedef enum eBrushSnakeHookDeformType {
+  BRUSH_SNAKE_HOOK_DEFORM_FALLOFF = 0,
+  BRUSH_SNAKE_HOOK_DEFORM_ELASTIC = 1,
+} eBrushSnakeHookDeformType;
+
 /* Gpencilsettings.Vertex_mode */
 typedef enum eGp_Vertex_Mode {
   /* Affect to Stroke only. */
@@ -573,7 +578,7 @@ typedef struct Brush {
   char gpencil_sculpt_tool;
   /** Active grease pencil weight tool. */
   char gpencil_weight_tool;
-  char _pad1[2];
+  char _pad1[6];
 
   float autosmooth_factor;
 
@@ -607,6 +612,9 @@ typedef struct Brush {
   int elastic_deform_type;
   float elastic_deform_volume_preservation;
 
+  /* snake hook */
+  int snake_hook_deform_type;
+
   /* pose */
   int pose_deform_type;
   float pose_offset;