Multires: Initial Face Sets support

This implements the Sculpt Mode API functions needed for Face Sets and
visibility management for PBVH_GRIDS. No major changes were needed in
the operators and the sculpt mode code. This implementation stores the
face sets in the base mesh, so faces created in higher subdivision
levels can't be modified individually. Also, we are not checking for
multiple face sets per vertex (that can be added in the future), so
relax tools don't work yet. The rest of the features (paint, undo,
visibility operators..) work as expected.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D7168

2 files changed, 48 insertions, 16 deletions

diff --git a/source/blender/gpu/GPU_buffers.h b/source/blender/gpu/GPU_buffers.h
index 9d91fd79137..b02f6ed09b3 100644
--- a/source/blender/gpu/GPU_buffers.h
+++ b/source/blender/gpu/GPU_buffers.h
@@ -95,10 +95,14 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                    const int update_flags);
 
 void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
+                                  struct SubdivCCG *subdiv_ccg,
                                   struct CCGElem **grids,
                                   const struct DMFlagMat *grid_flag_mats,
                                   int *grid_indices,
                                   int totgrid,
+                                  const int *sculpt_face_sets,
+                                  const int face_sets_color_seed,
+                                  const int face_sets_color_default,
                                   const struct CCGKey *key,
                                   const int update_flags);
 
diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index 168a3c83a91..cfc1eb05731 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -43,6 +43,7 @@
 #include "BKE_mesh.h"
 #include "BKE_paint.h"
 #include "BKE_pbvh.h"
+#include "BKE_subdiv_ccg.h"
 
 #include "GPU_batch.h"
 #include "GPU_buffers.h"
@@ -523,8 +524,13 @@ GPU_PBVH_Buffers *GPU_pbvh_mesh_buffers_build(const int (*face_vert_indices)[3],
 /** \name Grid PBVH
  * \{ */
 
-static void gpu_pbvh_grid_fill_index_buffers(
-    GPU_PBVH_Buffers *buffers, int *grid_indices, uint visible_quad_len, int totgrid, int gridsize)
+static void gpu_pbvh_grid_fill_index_buffers(GPU_PBVH_Buffers *buffers,
+                                             SubdivCCG *subdiv_ccg,
+                                             const int *face_sets,
+                                             int *grid_indices,
+                                             uint visible_quad_len,
+                                             int totgrid,
+                                             int gridsize)
 {
   GPUIndexBufBuilder elb, elb_lines;
   GPUIndexBufBuilder elb_fast, elb_lines_fast;
@@ -594,7 +600,6 @@ static void gpu_pbvh_grid_fill_index_buffers(
     const uint grid_vert_len = square_uint(gridsize - 1) * 4;
     for (int i = 0; i < totgrid; i++, offset += grid_vert_len) {
       bool grid_visible = false;
-
       BLI_bitmap *gh = buffers->grid_hidden[grid_indices[i]];
 
       uint v0, v1, v2, v3;
@@ -673,16 +678,22 @@ void GPU_pbvh_grid_buffers_update_free(GPU_PBVH_Buffers *buffers,
 
 /* Threaded - do not call any functions that use OpenGL calls! */
 void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
+                                  SubdivCCG *subdiv_ccg,
                                   CCGElem **grids,
-                                  const DMFlagMat *grid_flag_mats,
+                                  const struct DMFlagMat *grid_flag_mats,
                                   int *grid_indices,
                                   int totgrid,
-                                  const CCGKey *key,
+                                  const int *sculpt_face_sets,
+                                  const int face_sets_color_seed,
+                                  const int face_sets_color_default,
+                                  const struct CCGKey *key,
                                   const int update_flags)
 {
   const bool show_mask = (update_flags & GPU_PBVH_BUFFERS_SHOW_MASK) != 0;
   const bool show_vcol = (update_flags & GPU_PBVH_BUFFERS_SHOW_VCOL) != 0;
   bool empty_mask = true;
+  bool default_face_set = true;
+
   int i, j, k, x, y;
 
   /* Build VBO */
@@ -702,8 +713,13 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
       return;
     }
 
-    gpu_pbvh_grid_fill_index_buffers(
-        buffers, grid_indices, visible_quad_len, totgrid, key->grid_size);
+    gpu_pbvh_grid_fill_index_buffers(buffers,
+                                     subdiv_ccg,
+                                     sculpt_face_sets,
+                                     grid_indices,
+                                     visible_quad_len,
+                                     totgrid,
+                                     key->grid_size);
   }
 
   uint vbo_index_offset = 0;
@@ -716,9 +732,23 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
     }
 
     for (i = 0; i < totgrid; i++) {
-      CCGElem *grid = grids[grid_indices[i]];
+      const int grid_index = grid_indices[i];
+      CCGElem *grid = grids[grid_index];
       int vbo_index = vbo_index_offset;
 
+      uchar face_set_color[4] = {UCHAR_MAX, UCHAR_MAX, UCHAR_MAX, UCHAR_MAX};
+
+      if (subdiv_ccg && sculpt_face_sets) {
+        const int face_index = BKE_subdiv_cgg_grid_to_face_index(subdiv_ccg, grid_index);
+
+        const int fset = abs(sculpt_face_sets[face_index]);
+        /* Skip for the default color Face Set to render it white. */
+        if (fset != face_sets_color_default) {
+          face_set_overlay_color_get(fset, face_sets_color_seed, face_set_color);
+          default_face_set = false;
+        }
+      }
+
       if (buffers->smooth) {
         for (y = 0; y < key->grid_size; y++) {
           for (x = 0; x < key->grid_size; x++) {
@@ -742,8 +772,7 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
               GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, &vcol);
             }
 
-            uchar fsets[3] = {UCHAR_MAX, UCHAR_MAX, UCHAR_MAX};
-            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index, &fsets);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index, &face_set_color);
 
             vbo_index += 1;
           }
@@ -799,11 +828,10 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
             GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 2, &vcol);
             GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 3, &vcol);
 
-            uchar fsets[3] = {UCHAR_MAX, UCHAR_MAX, UCHAR_MAX};
-            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 0, &fsets);
-            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 1, &fsets);
-            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 2, &fsets);
-            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 3, &fsets);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 0, &face_set_color);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 1, &face_set_color);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 2, &face_set_color);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.fset, vbo_index + 3, &face_set_color);
 
             vbo_index += 4;
           }
@@ -823,7 +851,7 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
   buffers->totgrid = totgrid;
   buffers->grid_flag_mats = grid_flag_mats;
   buffers->gridkey = *key;
-  buffers->show_overlay = !empty_mask;
+  buffers->show_overlay = !empty_mask || !default_face_set;
 }
 
 /* Threaded - do not call any functions that use OpenGL calls! */