Workbench: Force Vertex Colors in Paint Mode

Vertex colors behaved differently as the paint overlay mixed the colors
in display mode and the results was multiplied on top of the original
shading.

This patch will align the implementation to texture painting where the
colors are drawn by the workbench engine so the correct shading is
applied.

This also means that we don't show the vertex colors overlay when not
in solid mode.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D6436

1 files changed, 47 insertions, 14 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_forward.c b/source/blender/draw/engines/workbench/workbench_forward.c
index 90f5d24fabd..44f43fc7d09 100644
--- a/source/blender/draw/engines/workbench/workbench_forward.c
+++ b/source/blender/draw/engines/workbench/workbench_forward.c
@@ -226,16 +226,16 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
 static GPUShader *ensure_forward_accum_shaders(WORKBENCH_PrivateData *wpd,
                                                bool is_uniform_color,
                                                bool is_hair,
-                                               bool is_texture_painting,
+                                               const WORKBENCH_ColorOverride color_override,
                                                eGPUShaderConfig sh_cfg)
 {
   WORKBENCH_FORWARD_Shaders *sh_data = &e_data.sh_data[sh_cfg];
   int index = workbench_material_get_accum_shader_index(
-      wpd, is_uniform_color, is_hair, is_texture_painting);
+      wpd, is_uniform_color, is_hair, color_override);
   if (sh_data->transparent_accum_sh_cache[index] == NULL) {
     const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
     char *defines = workbench_material_build_defines(
-        wpd, is_uniform_color, is_hair, is_texture_painting);
+        wpd, is_uniform_color, is_hair, color_override);
     char *transparent_accum_vert = workbench_build_forward_vert(is_hair);
     char *transparent_accum_frag = workbench_build_forward_transparent_accum_frag();
     sh_data->transparent_accum_sh_cache[index] = GPU_shader_create_from_arrays({
@@ -254,7 +254,8 @@ static GPUShader *ensure_forward_composite_shaders(WORKBENCH_PrivateData *wpd)
 {
   int index = OBJECT_OUTLINE_ENABLED(wpd) ? 1 : 0;
   if (e_data.composite_sh_cache[index] == NULL) {
-    char *defines = workbench_material_build_defines(wpd, false, false, false);
+    char *defines = workbench_material_build_defines(
+        wpd, false, false, WORKBENCH_COLOR_OVERRIDE_OFF);
     char *composite_frag = workbench_build_forward_composite_frag();
     e_data.composite_sh_cache[index] = DRW_shader_create_fullscreen(composite_frag, defines);
     MEM_freeN(composite_frag);
@@ -266,14 +267,18 @@ static GPUShader *ensure_forward_composite_shaders(WORKBENCH_PrivateData *wpd)
 void workbench_forward_choose_shaders(WORKBENCH_PrivateData *wpd, eGPUShaderConfig sh_cfg)
 {
   wpd->composite_sh = ensure_forward_composite_shaders(wpd);
-  wpd->transparent_accum_sh = ensure_forward_accum_shaders(wpd, false, false, false, sh_cfg);
-  wpd->transparent_accum_hair_sh = ensure_forward_accum_shaders(wpd, false, true, false, sh_cfg);
+  wpd->transparent_accum_sh = ensure_forward_accum_shaders(
+      wpd, false, false, WORKBENCH_COLOR_OVERRIDE_OFF, sh_cfg);
+  wpd->transparent_accum_hair_sh = ensure_forward_accum_shaders(
+      wpd, false, true, WORKBENCH_COLOR_OVERRIDE_OFF, sh_cfg);
   wpd->transparent_accum_uniform_sh = ensure_forward_accum_shaders(
-      wpd, true, false, false, sh_cfg);
+      wpd, true, false, WORKBENCH_COLOR_OVERRIDE_OFF, sh_cfg);
   wpd->transparent_accum_uniform_hair_sh = ensure_forward_accum_shaders(
-      wpd, true, true, false, sh_cfg);
+      wpd, true, true, WORKBENCH_COLOR_OVERRIDE_OFF, sh_cfg);
   wpd->transparent_accum_textured_sh = ensure_forward_accum_shaders(
-      wpd, false, false, true, sh_cfg);
+      wpd, false, false, WORKBENCH_COLOR_OVERRIDE_TEXTURE, sh_cfg);
+  wpd->transparent_accum_vertex_sh = ensure_forward_accum_shaders(
+      wpd, false, false, WORKBENCH_COLOR_OVERRIDE_VERTEX, sh_cfg);
 }
 
 void workbench_forward_outline_shaders_ensure(WORKBENCH_PrivateData *wpd, eGPUShaderConfig sh_cfg)
@@ -282,9 +287,12 @@ void workbench_forward_outline_shaders_ensure(WORKBENCH_PrivateData *wpd, eGPUSh
 
   if (sh_data->object_outline_sh == NULL) {
     const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
-    char *defines = workbench_material_build_defines(wpd, false, false, false);
-    char *defines_texture = workbench_material_build_defines(wpd, true, false, false);
-    char *defines_hair = workbench_material_build_defines(wpd, false, true, false);
+    char *defines = workbench_material_build_defines(
+        wpd, false, false, WORKBENCH_COLOR_OVERRIDE_OFF);
+    char *defines_texture = workbench_material_build_defines(
+        wpd, true, false, WORKBENCH_COLOR_OVERRIDE_OFF);
+    char *defines_hair = workbench_material_build_defines(
+        wpd, false, true, WORKBENCH_COLOR_OVERRIDE_OFF);
     char *forward_vert = workbench_build_forward_vert(false);
     char *forward_frag = workbench_build_forward_outline_frag();
     char *forward_hair_vert = workbench_build_forward_vert(true);
@@ -600,6 +608,23 @@ static void workbench_forward_cache_populate_texture_paint_mode(WORKBENCH_Data *
     }
   }
 }
+static void workbench_forward_cache_populate_vertex_paint_mode(WORKBENCH_Data *vedata, Object *ob)
+{
+  WORKBENCH_StorageList *stl = vedata->stl;
+  WORKBENCH_PrivateData *wpd = stl->g_data;
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+
+  const bool use_sculpt_pbvh = BKE_sculptsession_use_pbvh_draw(ob, draw_ctx->v3d) &&
+                               !DRW_state_is_image_render();
+  WORKBENCH_MaterialData *material;
+
+  int color_type = workbench_material_determine_color_type(wpd, NULL, ob, use_sculpt_pbvh);
+  struct GPUBatch *geom = DRW_cache_mesh_surface_vertpaint_get(ob);
+  material = workbench_forward_get_or_create_material_data(
+      vedata, ob, NULL, NULL, NULL, color_type, false);
+  DRW_shgroup_call(material->shgrp, geom, ob);
+  DRW_shgroup_call(material->shgrp_object_outline, geom, ob);
+}
 
 void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 {
@@ -640,14 +665,22 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
                                  !DRW_state_is_image_render();
     const int materials_len = MAX2(1, ob->totcol);
     const Mesh *me = (ob->type == OB_MESH) ? ob->data : NULL;
+    const WORKBENCH_ColorOverride color_override = workbench_object_color_override_get(ob);
     const bool use_texture_paint_drawing = !(DRW_state_is_image_render() &&
                                              draw_ctx->v3d == NULL) &&
-                                           workbench_is_object_in_texture_paint_mode(ob) && me &&
-                                           me->mloopuv;
+                                           (color_override == WORKBENCH_COLOR_OVERRIDE_TEXTURE) &&
+                                           me && me->mloopuv;
+    const bool use_vertex_paint_drawing = !(DRW_state_is_image_render() &&
+                                            draw_ctx->v3d == NULL) &&
+                                          (color_override == WORKBENCH_COLOR_OVERRIDE_VERTEX) &&
+                                          me && me->mloopcol;
 
     if (use_texture_paint_drawing) {
       workbench_forward_cache_populate_texture_paint_mode(vedata, ob);
     }
+    else if (use_vertex_paint_drawing) {
+      workbench_forward_cache_populate_vertex_paint_mode(vedata, ob);
+    }
     else if (!use_sculpt_pbvh && TEXTURE_DRAWING_ENABLED(wpd) && me && me->mloopuv) {
       struct GPUBatch **geom_array = DRW_cache_mesh_surface_texpaint_get(ob);
       for (int i = 0; i < materials_len; i++) {