Fix #110328: Clay Strip symmetry does not mirror rotation

Caused by 351034891e

This change is a partial revert of the change.

The SCULPT_cube_tip_init() does not deal with the symmetry passes.

Additionally, the commit changed the way how the Z component of
the matrix was constructed: displaced vs. non-displaced area
coordinate.

While the code duplication is often to be avoided, sometimes it is
more clear than a centralized place with a lot of arguments passed
to a function. We can have a pass of de-duplication later on, and
make a better decision, but for now restore user level behavior to
what it is expected to be.

Pull Request: https://projects.blender.org/blender/blender/pulls/111425

source/blender/editors/sculpt_paint/sculpt.cc

@@ -2964,9 +2964,7 @@ static void calc_local_y(ViewContext *vc, const float center[3], float y[3])
 static void calc_brush_local_mat(const float rotation,
                                  Object *ob,
                                  float local_mat[4][4],
-                                 float local_mat_inv[4][4],
-                                 const float *co,
-                                 const float *no)
+                                 float local_mat_inv[4][4])
 {
   const StrokeCache *cache = ob->sculpt->cache;
   float tmat[4][4];
@@ -2975,13 +2973,6 @@ static void calc_brush_local_mat(const float rotation,
   float angle, v[3];
   float up[3];
 
-  if (!co) {
-    co = cache->location;
-  }
-  if (!no) {
-    no = cache->sculpt_normal;
-  }
-
   /* Ensure `ob->world_to_object` is up to date. */
   invert_m4_m4(ob->world_to_object, ob->object_to_world);
 
@@ -2992,20 +2983,20 @@ static void calc_brush_local_mat(const float rotation,
   mat[3][3] = 1.0f;
 
   /* Get view's up vector in object-space. */
-  calc_local_y(cache->vc, co, up);
+  calc_local_y(cache->vc, cache->location, up);
 
   /* Calculate the X axis of the local matrix. */
-  cross_v3_v3v3(v, up, no);
+  cross_v3_v3v3(v, up, cache->sculpt_normal);
   /* Apply rotation (user angle, rake, etc.) to X axis. */
   angle = rotation - cache->special_rotation;
-  rotate_v3_v3v3fl(mat[0], v, no, angle);
+  rotate_v3_v3v3fl(mat[0], v, cache->sculpt_normal, angle);
 
   /* Get other axes. */
-  cross_v3_v3v3(mat[1], no, mat[0]);
-  copy_v3_v3(mat[2], no);
+  cross_v3_v3v3(mat[1], cache->sculpt_normal, mat[0]);
+  copy_v3_v3(mat[2], cache->sculpt_normal);
 
   /* Set location. */
-  copy_v3_v3(mat[3], co);
+  copy_v3_v3(mat[3], cache->location);
 
   /* Scale by brush radius. */
   float radius = cache->radius;
@@ -3050,8 +3041,7 @@ static void update_brush_local_mat(Sculpt *sd, Object *ob)
   if (cache->mirror_symmetry_pass == 0 && cache->radial_symmetry_pass == 0) {
     const Brush *brush = BKE_paint_brush(&sd->paint);
     const MTex *mask_tex = BKE_brush_mask_texture_get(brush, OB_MODE_SCULPT);
-    calc_brush_local_mat(
-        mask_tex->rot, ob, cache->brush_local_mat, cache->brush_local_mat_inv, nullptr, nullptr);
+    calc_brush_local_mat(mask_tex->rot, ob, cache->brush_local_mat, cache->brush_local_mat_inv);
   }
 }
 
@@ -6393,8 +6383,7 @@ void SCULPT_topology_islands_ensure(Object *ob)
   ss->islands_valid = true;
 }
 
-void SCULPT_cube_tip_init(
-    Sculpt * /*sd*/, Object *ob, Brush *brush, float mat[4][4], const float *co, const float *no)
+void SCULPT_cube_tip_init(Sculpt * /*sd*/, Object *ob, Brush *brush, float mat[4][4])
 {
   SculptSession *ss = ob->sculpt;
   float scale[4][4];
@@ -6402,7 +6391,7 @@ void SCULPT_cube_tip_init(
   float unused[4][4];
 
   zero_m4(mat);
-  calc_brush_local_mat(0.0, ob, unused, mat, co, no);
+  calc_brush_local_mat(0.0, ob, unused, mat);
 
   /* Note: we ignore the radius scaling done inside of calc_brush_local_mat to
    * duplicate prior behavior.

source/blender/editors/sculpt_paint/sculpt_brush_types.cc

@@ -1119,6 +1119,8 @@ void SCULPT_do_clay_strips_brush(Sculpt *sd, Object *ob, Span<PBVHNode *> nodes)
 
   float temp[3];
   float mat[4][4];
+  float scale[4][4];
+  float tmat[4][4];
 
   SCULPT_calc_brush_plane(sd, ob, nodes, area_no_sp, area_co);
   SCULPT_tilt_apply_to_normal(area_no_sp, ss->cache, brush->tilt_strength_factor);
@@ -1130,6 +1132,10 @@ void SCULPT_do_clay_strips_brush(Sculpt *sd, Object *ob, Span<PBVHNode *> nodes)
     copy_v3_v3(area_no, area_no_sp);
   }
 
+  if (is_zero_v3(ss->cache->grab_delta_symmetry)) {
+    return;
+  }
+
   mul_v3_v3v3(temp, area_no_sp, ss->cache->scale);
   mul_v3_fl(temp, displace);
   add_v3_v3(area_co, temp);
@@ -1145,21 +1151,6 @@ void SCULPT_do_clay_strips_brush(Sculpt *sd, Object *ob, Span<PBVHNode *> nodes)
   float area_co_displaced[3];
   madd_v3_v3v3fl(area_co_displaced, area_co, area_no, -radius * 0.7f);
 
-  /* Initialize brush local-space matrix. */
-  SCULPT_cube_tip_init(sd, ob, brush, mat, area_co, area_no);
-
-  /* Deform the local space in Z to scale the test cube. As the test cube does not have falloff in
-   * Z this does not produce artifacts in the falloff cube and allows to deform extra vertices
-   * during big deformation while keeping the surface as uniform as possible. */
-  invert_m4(mat);
-  mul_v3_fl(mat[2], 1.25f);
-  invert_m4(mat);
-
-#if 0 /* The original matrix construction code, preserved here for reference. */
-  if (is_zero_v3(ss->cache->grab_delta_symmetry)) {
-    return;
-  }
-
   cross_v3_v3v3(mat[0], area_no, ss->cache->grab_delta_symmetry);
   mat[0][3] = 0.0f;
   cross_v3_v3v3(mat[1], area_no, mat[0]);
@@ -1174,8 +1165,14 @@ void SCULPT_do_clay_strips_brush(Sculpt *sd, Object *ob, Span<PBVHNode *> nodes)
   scale_m4_fl(scale, ss->cache->radius);
   mul_m4_m4m4(tmat, mat, scale);
 
+  mul_v3_fl(tmat[1], brush->tip_scale_x);
+
+  /* Deform the local space in Z to scale the test cube. As the test cube does not have falloff in
+   * Z this does not produce artifacts in the falloff cube and allows to deform extra vertices
+   * during big deformation while keeping the surface as uniform as possible. */
+  mul_v3_fl(tmat[2], 1.25f);
+
   invert_m4_m4(mat, tmat);
-#endif
 
   SculptThreadedTaskData data{};
   data.sd = sd;

source/blender/editors/sculpt_paint/sculpt_intern.hh

@@ -1260,12 +1260,7 @@ SculptBrushTestFn SCULPT_brush_test_init_with_falloff_shape(SculptSession *ss,
                                                             char falloff_shape);
 const float *SCULPT_brush_frontface_normal_from_falloff_shape(SculptSession *ss,
                                                               char falloff_shape);
-void SCULPT_cube_tip_init(Sculpt *sd,
-                          Object *ob,
-                          Brush *brush,
-                          float mat[4][4],
-                          const float *co = nullptr,  /* Custom brush center. */
-                          const float *no = nullptr); /* Custom brush normal. */
+void SCULPT_cube_tip_init(Sculpt *sd, Object *ob, Brush *brush, float mat[4][4]);
 
 /**
  * Return a multiplier for brush strength on a particular vertex.