Sculpt Face Sets

Face Sets are the new system to control the visibility state of the mesh in sculpt and paint modes. They are designed to work in modes where brushes are the primary way of interaction and they provide much more control when working with meshes with complex shapes and overlapping surfaces.

This initial commit includes:
- Sculpt Face Sets data structures and PBVH rendering.
- Face Set overlay and opacity controls.
- Sculpt Undo support.
- Remesher reprojection support. The visibility state of the mesh is also preserved when remeshing.
- Automasking and Mesh filter support.
- Mask expand operator mode to expand Face Sets (Shift + W) and flood fill areas by connectivity (press Ctrl while expanding).
- Sculpt Mode Face Sets and Visibility API.
- Sculpt Face Sets creation and visibility management operators.
- Operator to randomize the Face Sets colors.
- Draw Face Sets brush tool to create and edit the Face Sets. Drawing on the mesh creates a new Face Set. Pressing Ctrl before drawing modifies the Face Set under the brush at the beginning of the stroke.
- Updated keymap and menu to work with Face Sets from Sculpt Mode (H to toggle visibility, Alt + H to show all, Shit + H to hide).
- Pie menu on the W key with Face common Sets operations.

Know limitations:
- Multires support. The Face Sets and Visibility API needs to be implemented for Multires.

Reviewed By: jbakker, #user_interface, Severin

Differential Revision: https://developer.blender.org/D6070

3 files changed, 11 insertions, 10 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_sculpt.c b/source/blender/draw/engines/overlay/overlay_sculpt.c
index dc286d36e9e..ba37f56800b 100644
--- a/source/blender/draw/engines/overlay/overlay_sculpt.c
+++ b/source/blender/draw/engines/overlay/overlay_sculpt.c
@@ -34,12 +34,14 @@ void OVERLAY_sculpt_cache_init(OVERLAY_Data *vedata)
   OVERLAY_PrivateData *pd = vedata->stl->pd;
   DRWShadingGroup *grp;
 
-  DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_BLEND_ALPHA;
+  DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_BLEND_MUL;
   DRW_PASS_CREATE(psl->sculpt_mask_ps, state | pd->clipping_state);
 
   GPUShader *sh = OVERLAY_shader_sculpt_mask();
   pd->sculpt_mask_grp = grp = DRW_shgroup_create(sh, psl->sculpt_mask_ps);
   DRW_shgroup_uniform_float_copy(grp, "maskOpacity", pd->overlay.sculpt_mode_mask_opacity);
+  DRW_shgroup_uniform_float_copy(
+      grp, "faceSetsOpacity", pd->overlay.sculpt_mode_face_sets_opacity);
 }
 
 void OVERLAY_sculpt_cache_populate(OVERLAY_Data *vedata, Object *ob)
@@ -51,7 +53,7 @@ void OVERLAY_sculpt_cache_populate(OVERLAY_Data *vedata, Object *ob)
   const bool use_pbvh = BKE_sculptsession_use_pbvh_draw(ob, draw_ctx->v3d);
 
   if (use_pbvh || !ob->sculpt->deform_modifiers_active || ob->sculpt->shapekey_active) {
-    if (!use_pbvh || pbvh_has_mask(pbvh)) {
+    if (!use_pbvh || pbvh_has_mask(pbvh) || pbvh_has_face_sets(pbvh)) {
       DRW_shgroup_call_sculpt(pd->sculpt_mask_grp, ob, false, true, false);
     }
   }
@@ -60,10 +62,10 @@ void OVERLAY_sculpt_cache_populate(OVERLAY_Data *vedata, Object *ob)
 void OVERLAY_sculpt_draw(OVERLAY_Data *vedata)
 {
   OVERLAY_PassList *psl = vedata->psl;
-  OVERLAY_FramebufferList *fbl = vedata->fbl;
+  DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
 
   if (DRW_state_is_fbo()) {
-    GPU_framebuffer_bind(fbl->overlay_default_fb);
+    GPU_framebuffer_bind(dfbl->default_fb);
   }
 
   DRW_draw_pass(psl->sculpt_mask_ps);
diff --git a/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl b/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl
index 38559677706..5d79195a40b 100644
--- a/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl
+++ b/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl
@@ -1,7 +1,9 @@
 
 uniform float maskOpacity;
+uniform float faceSetsOpacity;
 
 in vec3 pos;
+in vec3 fset;
 in float msk;
 
 out vec4 finalColor;
@@ -11,7 +13,8 @@ void main()
   vec3 world_pos = point_object_to_world(pos);
   gl_Position = point_world_to_ndc(world_pos);
 
-  finalColor = vec4(0.0, 0.0, 0.0, msk * maskOpacity);
+  finalColor = vec4(mix(vec3(1.0), fset, faceSetsOpacity), 1.0);
+  finalColor.rgb *= (1.0 - (msk * maskOpacity));
 
 #ifdef USE_WORLD_CLIP_PLANES
   world_clip_planes_calc_clip_distance(world_pos);
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index 6f2a9cc056f..28d5daf011c 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -823,6 +823,7 @@ typedef struct DRWSculptCallbackData {
   bool use_wire;
   bool use_mats;
   bool use_mask;
+  bool use_fsets;
   bool fast_mode; /* Set by draw manager. Do not init. */
 
   int debug_node_nr;
@@ -843,11 +844,6 @@ static float sculpt_debug_colors[9][4] = {
 
 static void sculpt_draw_cb(DRWSculptCallbackData *scd, GPU_PBVH_Buffers *buffers)
 {
-  /* Meh... use_mask is a bit misleading here. */
-  if (scd->use_mask && !GPU_pbvh_buffers_has_mask(buffers)) {
-    return;
-  }
-
   GPUBatch *geom = GPU_pbvh_buffers_batch_get(buffers, scd->fast_mode, scd->use_wire);
   short index = 0;