Sculpt: Render Face Sets always as flat shading

This removes the smooth shading rendering from the face set overlay when
smooth shading is enabled.

Reviewed By: jbakker

Maniphest Tasks: T74906, T74622, T75331, T76530

Differential Revision: https://developer.blender.org/D7105

4 files changed, 18 insertions, 3 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 46263f694cb..6f932bf8797 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -384,6 +384,7 @@ data_to_c_simple(engines/overlay/shaders/particle_frag.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/pointcloud_vert.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/pointcloud_frag.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/sculpt_mask_vert.glsl SRC)
+data_to_c_simple(engines/overlay/shaders/sculpt_mask_frag.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/volume_velocity_vert.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/wireframe_vert.glsl SRC)
 data_to_c_simple(engines/overlay/shaders/wireframe_frag.glsl SRC)
diff --git a/source/blender/draw/engines/overlay/overlay_shader.c b/source/blender/draw/engines/overlay/overlay_shader.c
index 264791a6661..59f388df4e3 100644
--- a/source/blender/draw/engines/overlay/overlay_shader.c
+++ b/source/blender/draw/engines/overlay/overlay_shader.c
@@ -105,6 +105,7 @@ extern char datatoc_particle_frag_glsl[];
 extern char datatoc_pointcloud_vert_glsl[];
 extern char datatoc_pointcloud_frag_glsl[];
 extern char datatoc_sculpt_mask_vert_glsl[];
+extern char datatoc_sculpt_mask_frag_glsl[];
 extern char datatoc_volume_velocity_vert_glsl[];
 extern char datatoc_wireframe_vert_glsl[];
 extern char datatoc_wireframe_frag_glsl[];
@@ -1307,7 +1308,7 @@ GPUShader *OVERLAY_shader_sculpt_mask(void)
                                  datatoc_common_view_lib_glsl,
                                  datatoc_sculpt_mask_vert_glsl,
                                  NULL},
-        .frag = (const char *[]){datatoc_gpu_shader_3D_smooth_color_frag_glsl, NULL},
+        .frag = (const char *[]){datatoc_sculpt_mask_frag_glsl, NULL},
         .defs = (const char *[]){sh_cfg->def, NULL},
     });
   }
diff --git a/source/blender/draw/engines/overlay/shaders/sculpt_mask_frag.glsl b/source/blender/draw/engines/overlay/shaders/sculpt_mask_frag.glsl
new file mode 100644
index 00000000000..a778e518392
--- /dev/null
+++ b/source/blender/draw/engines/overlay/shaders/sculpt_mask_frag.glsl
@@ -0,0 +1,10 @@
+
+flat in vec3 faceset_color;
+in float mask_color;
+
+out vec4 fragColor;
+
+void main()
+{
+  fragColor = vec4(faceset_color * vec3(mask_color), 1.0);
+}
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 5d79195a40b..f2b827738ac 100644
--- a/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl
+++ b/source/blender/draw/engines/overlay/shaders/sculpt_mask_vert.glsl
@@ -8,13 +8,16 @@ in float msk;
 
 out vec4 finalColor;
 
+flat out vec3 faceset_color;
+out float mask_color;
+
 void main()
 {
   vec3 world_pos = point_object_to_world(pos);
   gl_Position = point_world_to_ndc(world_pos);
 
-  finalColor = vec4(mix(vec3(1.0), fset, faceSetsOpacity), 1.0);
-  finalColor.rgb *= (1.0 - (msk * maskOpacity));
+  faceset_color = mix(vec3(1.0), fset, faceSetsOpacity);
+  mask_color = 1.0 - (msk * maskOpacity);
 
 #ifdef USE_WORLD_CLIP_PLANES
   world_clip_planes_calc_clip_distance(world_pos);