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, 18 insertions, 10 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index e1c1b8ee5fb..f8cd7dfe262 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -2273,7 +2273,7 @@ static float brush_strength(const Sculpt *sd,
     case SCULPT_TOOL_DISPLACEMENT_ERASER:
       return alpha * pressure * overlap * feather;
     case SCULPT_TOOL_CLOTH:
-      if (brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_GRAB) {
+      if (ELEM(brush->cloth_deform_type, BRUSH_CLOTH_DEFORM_GRAB, BRUSH_CLOTH_DEFORM_SNAKE_HOOK)) {
         /* Grab deform uses the same falloff as a regular grab brush. */
         return root_alpha * feather;
       }
@@ -6634,13 +6634,19 @@ static float sculpt_brush_dynamic_size_get(Brush *brush, StrokeCache *cache, flo
  * generally used to create grab deformations. */
 static bool sculpt_needs_delta_from_anchored_origin(Brush *brush)
 {
-  return ELEM(brush->sculpt_tool,
-              SCULPT_TOOL_GRAB,
-              SCULPT_TOOL_POSE,
-              SCULPT_TOOL_BOUNDARY,
-              SCULPT_TOOL_THUMB,
-              SCULPT_TOOL_ELASTIC_DEFORM) ||
-         SCULPT_is_cloth_deform_brush(brush);
+  if ELEM (brush->sculpt_tool,
+           SCULPT_TOOL_GRAB,
+           SCULPT_TOOL_POSE,
+           SCULPT_TOOL_BOUNDARY,
+           SCULPT_TOOL_THUMB,
+           SCULPT_TOOL_ELASTIC_DEFORM) {
+    return true;
+  }
+  if (brush->sculpt_tool == SCULPT_TOOL_CLOTH &&
+      brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_GRAB) {
+    return true;
+  }
+  return false;
 }
 
 /* In these brushes the grab delta is calculated from the previous stroke location, which is used
@@ -6648,7 +6654,7 @@ static bool sculpt_needs_delta_from_anchored_origin(Brush *brush)
 static bool sculpt_needs_delta_for_tip_orientation(Brush *brush)
 {
   if (brush->sculpt_tool == SCULPT_TOOL_CLOTH) {
-    return !SCULPT_is_cloth_deform_brush(brush);
+    return brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_SNAKE_HOOK;
   }
   return ELEM(brush->sculpt_tool,
               SCULPT_TOOL_CLAY_STRIPS,
@@ -6694,7 +6700,9 @@ static void sculpt_update_brush_delta(UnifiedPaintSettings *ups, Object *ob, Bru
         copy_v3_v3(cache->orig_grab_location, cache->true_location);
       }
     }
-    else if (tool == SCULPT_TOOL_SNAKE_HOOK) {
+    else if (tool == SCULPT_TOOL_SNAKE_HOOK ||
+             (tool == SCULPT_TOOL_CLOTH &&
+              brush->cloth_deform_type == BRUSH_CLOTH_DEFORM_SNAKE_HOOK)) {
       add_v3_v3(cache->true_location, cache->grab_delta);
     }