Fix sculpt pen tilt support changing the brush strength

SCULPT_tilt_apply_to_normal expects a normal, and offset was already
scaled by radius. The funcion returns a normalized vector, so the
strength of the brush was changed.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9275

1 files changed, 12 insertions, 4 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 3ded57d938f..adc62b23559 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -2810,6 +2810,12 @@ void SCULPT_tilt_apply_to_normal(float r_normal[3], StrokeCache *cache, const fl
   normalize_v3(r_normal);
 }
 
+void SCULPT_tilt_effective_normal_get(const SculptSession *ss, const Brush *brush, float r_no[3])
+{
+  copy_v3_v3(r_no, ss->cache->sculpt_normal_symm);
+  SCULPT_tilt_apply_to_normal(r_no, ss->cache, brush->tilt_strength_factor);
+}
+
 static void update_brush_local_mat(Sculpt *sd, Object *ob)
 {
   StrokeCache *cache = ob->sculpt->cache;
@@ -3119,8 +3125,9 @@ static void do_draw_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
   const float bstrength = ss->cache->bstrength;
 
   /* Offset with as much as possible factored in already. */
-  mul_v3_v3fl(offset, ss->cache->sculpt_normal_symm, ss->cache->radius);
-  SCULPT_tilt_apply_to_normal(offset, ss->cache, brush->tilt_strength_factor);
+  float effective_normal[3];
+  SCULPT_tilt_effective_normal_get(ss, brush, effective_normal);
+  mul_v3_v3fl(offset, effective_normal, ss->cache->radius);
   mul_v3_v3(offset, ss->cache->scale);
   mul_v3_fl(offset, bstrength);
 
@@ -3197,8 +3204,9 @@ static void do_draw_sharp_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int to
   const float bstrength = ss->cache->bstrength;
 
   /* Offset with as much as possible factored in already. */
-  mul_v3_v3fl(offset, ss->cache->sculpt_normal_symm, ss->cache->radius);
-  SCULPT_tilt_apply_to_normal(offset, ss->cache, brush->tilt_strength_factor);
+  float effective_normal[3];
+  SCULPT_tilt_effective_normal_get(ss, brush, effective_normal);
+  mul_v3_v3fl(offset, effective_normal, ss->cache->radius);
   mul_v3_v3(offset, ss->cache->scale);
   mul_v3_fl(offset, bstrength);