Sculpt: New Cavity Automasking Mode

Add new cavity automasking mode based on local mesh
curvature.  Cavity masking is a great way to quickly add
detail in crevices and the like.  It's meant to be used
with the Paint brush in color attribute mode.  It does
work with other brushes but the results can be unpredictable.

{F13131497}

The old "dirty mask" operator has been replace with a new
"mask from cavity" operator that shares the same code with
cavity automasking.

Differences from the sculpt-dev implementation:
    * It uses the word "cavity."  When I first implemented
this I wasn't aware
      this feature existed in other software (and other
paint modes in Blender),
      and for reasons that escape me today I initially
decided to call it a concave or
      concavity mask.
    * The cavity factor works a bit differently.  It's
      no longer non-linear and functions as a simple
      scale around 0.5f.
    * Supports custom curves.
    * Supports blurring.

Reviewed By: Julian Kaspar, Jeroen Bakker and Campbell Barton
Differential Revision: https://developer.blender.org/D15122
Ref D15122

1 files changed, 35 insertions, 0 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 114c2c3839a..ac77e007081 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -3364,6 +3364,8 @@ static void do_brush_action(Sculpt *sd,
       /* Initialize auto-masking cache. */
       if (SCULPT_is_automasking_enabled(sd, ss, brush)) {
         ss->cache->automasking = SCULPT_automasking_cache_init(sd, brush, ob);
+        ss->last_automasking_settings_hash = SCULPT_automasking_settings_hash(
+            ob, ss->cache->automasking);
       }
       /* Initialize surface smooth cache. */
       if ((brush->sculpt_tool == SCULPT_TOOL_SMOOTH) &&
@@ -3546,6 +3548,11 @@ static void do_brush_action(Sculpt *sd,
     SCULPT_bmesh_topology_rake(sd, ob, nodes, totnode, brush->topology_rake_factor);
   }
 
+  if (!SCULPT_tool_can_reuse_cavity_mask(brush->sculpt_tool) || (ss->cache->supports_gravity && sd->gravity_factor > 0.0f)) {
+    /* Clear cavity mask cache. */
+    ss->last_automasking_settings_hash = 0;
+  }
+
   /* The cloth brush adds the gravity as a regular force and it is processed in the solver. */
   if (ss->cache->supports_gravity && !ELEM(brush->sculpt_tool,
                                            SCULPT_TOOL_CLOTH,
@@ -4234,6 +4241,8 @@ static void sculpt_update_cache_invariants(
 
   ss->cache = cache;
 
+  cache->stroke_id = ss->stroke_id;
+
   /* Set scaling adjustment. */
   max_scale = 0.0f;
   for (int i = 0; i < 3; i++) {
@@ -4339,6 +4348,10 @@ static void sculpt_update_cache_invariants(
     cache->original = true;
   }
 
+  if (SCULPT_automasking_needs_original(sd, brush)) {
+    cache->original = true;
+  }
+
   /* Draw sharp does not need the original coordinates to produce the accumulate effect, so it
    * should work the opposite way. */
   if (brush->sculpt_tool == SCULPT_TOOL_DRAW_SHARP) {
@@ -5398,6 +5411,8 @@ static bool sculpt_stroke_test_start(bContext *C, struct wmOperator *op, const f
       SCULPT_undo_push_begin_ex(ob, sculpt_tool_name(sd));
     }
 
+    SCULPT_stroke_id_next(ob);
+
     return true;
   }
   return false;
@@ -5996,4 +6011,24 @@ void SCULPT_fake_neighbors_free(Object *ob)
   sculpt_pose_fake_neighbors_free(ss);
 }
 
+void SCULPT_stroke_id_next(Object *ob)
+{
+  /* Manually wrap in int32 space to avoid tripping up undefined behavior
+   * sanitizers.
+   */
+  ob->sculpt->stroke_id = (uchar)(((int)ob->sculpt->stroke_id + 1) & 255);
+}
+
+void SCULPT_stroke_id_ensure(Object *ob)
+{
+  SculptSession *ss = ob->sculpt;
+
+  if (!ss->attrs.stroke_id) {
+    SculptAttributeParams params = {0};
+
+    ss->attrs.stroke_id = BKE_sculpt_attribute_ensure(
+        ob, ATTR_DOMAIN_POINT, CD_PROP_INT8, SCULPT_ATTRIBUTE_NAME(stroke_id), &params);
+  }
+}
+
 /** \} */