Refactor: Unify vertex and sculpt colors into new

          color attribute system.

This commit removes sculpt colors from experimental
status and unifies it with vertex colors. It
introduces the concept of "color attributes", which
are any attributes that represents colors.  Color
attributes can be represented with byte or floating-point
numbers and can be stored in either vertices or
face corners.

Color attributes share a common namespace
(so you can no longer have a floating-point
sculpt color attribute and a byte vertex color
attribute with the same name).

Note: this commit does not include vertex paint mode,
      which is a separate patch, see:
      https://developer.blender.org/D14179

Differential Revision: https://developer.blender.org/D12587
Ref D12587

1 files changed, 100 insertions, 28 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_paint_color.c b/source/blender/editors/sculpt_paint/sculpt_paint_color.c
index 5d248cb520a..cc4392c6a8a 100644
--- a/source/blender/editors/sculpt_paint/sculpt_paint_color.c
+++ b/source/blender/editors/sculpt_paint/sculpt_paint_color.c
@@ -85,7 +85,11 @@ static void do_color_smooth_task_cb_exec(void *__restrict userdata,
 
     float smooth_color[4];
     SCULPT_neighbor_color_average(ss, smooth_color, vd.index);
-    blend_color_interpolate_float(vd.col, vd.col, smooth_color, fade);
+    float col[4];
+
+    SCULPT_vertex_color_get(ss, vd.index, col);
+    blend_color_interpolate_float(col, col, smooth_color, fade);
+    SCULPT_vertex_color_set(ss, vd.index, col);
 
     if (vd.mvert) {
       BKE_pbvh_vert_mark_update(ss->pbvh, vd.index);
@@ -154,7 +158,7 @@ static void do_paint_brush_task_cb_ex(void *__restrict userdata,
     float noise = 1.0f;
     const float density = ss->cache->paint_brush.density;
     if (density < 1.0f) {
-      const float hash_noise = BLI_hash_int_01(ss->cache->density_seed * 1000 * vd.index);
+      const float hash_noise = (float) BLI_hash_int_01(ss->cache->density_seed * 1000 * vd.index);
       if (hash_noise > density) {
         noise = density * hash_noise;
         fade = fade * noise;
@@ -177,9 +181,11 @@ static void do_paint_brush_task_cb_ex(void *__restrict userdata,
     /* Final mix over the original color using brush alpha. */
     mul_v4_v4fl(buffer_color, color_buffer->color[vd.i], brush->alpha);
 
-    IMB_blend_color_float(vd.col, orig_data.col, buffer_color, brush->blend);
-
-    CLAMP4(vd.col, 0.0f, 1.0f);
+    float col[4];
+    SCULPT_vertex_color_get(ss, vd.index, col);
+    IMB_blend_color_float(col, orig_data.col, buffer_color, brush->blend);
+    CLAMP4(col, 0.0f, 1.0f);
+    SCULPT_vertex_color_set(ss, vd.index, col);
 
     if (vd.mvert) {
       BKE_pbvh_vert_mark_update(ss->pbvh, vd.index);
@@ -214,7 +220,10 @@ static void do_sample_wet_paint_task_cb(void *__restrict userdata,
       continue;
     }
 
-    add_v4_v4(swptd->color, vd.col);
+    float col[4];
+    SCULPT_vertex_color_get(ss, vd.index, col);
+
+    add_v4_v4(swptd->color, col);
     swptd->tot_samples++;
   }
   BKE_pbvh_vertex_iter_end;
@@ -236,13 +245,13 @@ void SCULPT_do_paint_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode
   Brush *brush = BKE_paint_brush(&sd->paint);
   SculptSession *ss = ob->sculpt;
 
-  if (!ss->vcol) {
+  if (!SCULPT_has_colors(ss)) {
     return;
   }
 
   if (SCULPT_stroke_is_first_brush_step_of_symmetry_pass(ss->cache)) {
     if (SCULPT_stroke_is_first_brush_step(ss->cache)) {
-      ss->cache->density_seed = BLI_hash_int_01(ss->cache->location[0] * 1000);
+      ss->cache->density_seed = (float) BLI_hash_int_01(ss->cache->location[0] * 1000);
     }
     return;
   }
@@ -384,6 +393,9 @@ static void do_smear_brush_task_cb_exec(void *__restrict userdata,
     float interp_color[4];
     copy_v4_v4(interp_color, ss->cache->prev_colors[vd.index]);
 
+    float no[3];
+    SCULPT_vertex_normal_get(ss, vd.index, no);
+
     switch (brush->smear_deform_type) {
       case BRUSH_SMEAR_DEFORM_DRAG:
         sub_v3_v3v3(current_disp, ss->cache->location, ss->cache->last_location);
@@ -395,29 +407,89 @@ static void do_smear_brush_task_cb_exec(void *__restrict userdata,
         sub_v3_v3v3(current_disp, vd.co, ss->cache->location);
         break;
     }
+
+    /* Project into vertex plane. */
+    madd_v3_v3fl(current_disp, no, -dot_v3v3(current_disp, no));
+
     normalize_v3_v3(current_disp_norm, current_disp);
     mul_v3_v3fl(current_disp, current_disp_norm, ss->cache->bstrength);
 
-    SculptVertexNeighborIter ni;
-    SCULPT_VERTEX_NEIGHBORS_ITER_BEGIN (ss, vd.index, ni) {
-      float vertex_disp[3];
-      float vertex_disp_norm[3];
-      sub_v3_v3v3(vertex_disp, SCULPT_vertex_co_get(ss, ni.index), vd.co);
-      const float *neighbor_color = ss->cache->prev_colors[ni.index];
-      normalize_v3_v3(vertex_disp_norm, vertex_disp);
-      if (dot_v3v3(current_disp_norm, vertex_disp_norm) >= 0.0f) {
-        continue;
+    float accum[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+    float totw = 0.0f;
+
+    /*
+     * NOTE: we have to do a nested iteration here to avoid
+     * blocky artifacts on quad topologies.  The runtime cost
+     * is not as bad as it seems due to neighbor iteration
+     * in the sculpt code being cache bound; once the data is in
+     * the cache iterating over it a few more times is not terribly
+     * costly.
+     */
+
+    SculptVertexNeighborIter ni2;
+    SCULPT_VERTEX_NEIGHBORS_ITER_BEGIN (ss, vd.index, ni2) {
+      const float *nco = SCULPT_vertex_co_get(ss, ni2.index);
+
+      SculptVertexNeighborIter ni;
+      SCULPT_VERTEX_NEIGHBORS_ITER_BEGIN (ss, ni2.index, ni) {
+        if (ni.index == vd.index) {
+          continue;
+        }
+
+        float vertex_disp[3];
+        float vertex_disp_norm[3];
+
+        sub_v3_v3v3(vertex_disp, SCULPT_vertex_co_get(ss, ni.index), vd.co);
+
+        /* Weight by how close we are to our target distance from vd.co. */
+        float w = (1.0f + fabsf(len_v3(vertex_disp) / ss->cache->bstrength - 1.0f));
+
+        /* TODO: use cotangents (or at least face areas) here. */
+        float len = len_v3v3(SCULPT_vertex_co_get(ss, ni.index), nco);
+        if (len > 0.0f) {
+          len = ss->cache->bstrength / len;
+        }
+        else { /* Coincident point. */
+          len = 1.0f;
+        }
+
+        /* Multiply weight with edge lengths (in the future this will be
+           cotangent weights or face areas). */
+        w *= len;
+
+        /* Build directional weight. */
+
+        /* Project into vertex plane. */
+        madd_v3_v3fl(vertex_disp, no, -dot_v3v3(no, vertex_disp));
+        normalize_v3_v3(vertex_disp_norm, vertex_disp);
+
+        if (dot_v3v3(current_disp_norm, vertex_disp_norm) >= 0.0f) {
+          continue;
+        }
+
+        const float *neighbor_color = ss->cache->prev_colors[ni.index];
+        float color_interp = -dot_v3v3(current_disp_norm, vertex_disp_norm);
+
+        /* Square directional weight to get a somewhat sharper result. */
+        w *= color_interp * color_interp;
+
+        madd_v4_v4fl(accum, neighbor_color, w);
+        totw += w;
       }
-      const float color_interp = clamp_f(
-          -dot_v3v3(current_disp_norm, vertex_disp_norm), 0.0f, 1.0f);
-      float color_mix[4];
-      copy_v4_v4(color_mix, neighbor_color);
-      mul_v4_fl(color_mix, color_interp * fade);
-      blend_color_mix_float(interp_color, interp_color, color_mix);
+      SCULPT_VERTEX_NEIGHBORS_ITER_END(ni);
     }
-    SCULPT_VERTEX_NEIGHBORS_ITER_END(ni);
+    SCULPT_VERTEX_NEIGHBORS_ITER_END(ni2);
+
+    if (totw != 0.0f) {
+      mul_v4_fl(accum, 1.0f / totw);
+    }
+
+    blend_color_mix_float(interp_color, interp_color, accum);
 
-    blend_color_interpolate_float(vd.col, ss->cache->prev_colors[vd.index], interp_color, fade);
+    float col[4];
+    SCULPT_vertex_color_get(ss, vd.index, col);
+    blend_color_interpolate_float(col, ss->cache->prev_colors[vd.index], interp_color, fade);
+    SCULPT_vertex_color_set(ss, vd.index, col);
 
     if (vd.mvert) {
       BKE_pbvh_vert_mark_update(ss->pbvh, vd.index);
@@ -435,7 +507,7 @@ static void do_smear_store_prev_colors_task_cb_exec(void *__restrict userdata,
 
   PBVHVertexIter vd;
   BKE_pbvh_vertex_iter_begin (ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE) {
-    copy_v4_v4(ss->cache->prev_colors[vd.index], SCULPT_vertex_color_get(ss, vd.index));
+    SCULPT_vertex_color_get(ss, vd.index, ss->cache->prev_colors[vd.index]);
   }
   BKE_pbvh_vertex_iter_end;
 }
@@ -445,7 +517,7 @@ void SCULPT_do_smear_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode
   Brush *brush = BKE_paint_brush(&sd->paint);
   SculptSession *ss = ob->sculpt;
 
-  if (!ss->vcol) {
+  if (!SCULPT_has_colors(ss)) {
     return;
   }
 
@@ -455,7 +527,7 @@ void SCULPT_do_smear_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode
     if (!ss->cache->prev_colors) {
       ss->cache->prev_colors = MEM_callocN(sizeof(float[4]) * totvert, "prev colors");
       for (int i = 0; i < totvert; i++) {
-        copy_v4_v4(ss->cache->prev_colors[i], SCULPT_vertex_color_get(ss, i));
+        SCULPT_vertex_color_get(ss, i, ss->cache->prev_colors[i]);
       }
     }
   }