Workbench: Support Active Vertex Color

Currently it is not possible to view the vertex colors of an object. To
optimize the workflow, workbench will need to support Vertex Colors.

The Vertex Colors is a new option in `shading->color_type`. When objects
do not have vertex color, the objects will be rendered with the
`V3D_SHADING_OBJECT_COLOR`.

In order to support vertex colors in workbench the current texture/solid
shading structure is migrated to a primary shaders and fallback shaders.

Fix: T57000

Reviewers: brecht, fclem

Differential Revision: https://developer.blender.org/D4694

1 files changed, 45 insertions, 1 deletions

diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index 9b89fc3a4a2..ebe5fcf4496 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -91,7 +91,7 @@ struct GPU_PBVH_Buffers {
 };
 
 static struct {
-  uint pos, nor, msk;
+  uint pos, nor, msk, col;
 } g_vbo_id = {0};
 
 /** \} */
@@ -131,7 +131,10 @@ static bool gpu_pbvh_vert_buf_data_set(GPU_PBVH_Buffers *buffers, uint vert_len)
       g_vbo_id.pos = GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
       g_vbo_id.nor = GPU_vertformat_attr_add(
           &format, "nor", GPU_COMP_I16, 3, GPU_FETCH_INT_TO_FLOAT_UNIT);
+      /* TODO: Do not allocate these `.msk` and `.col` when they are not used. */
       g_vbo_id.msk = GPU_vertformat_attr_add(&format, "msk", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
+      g_vbo_id.col = GPU_vertformat_attr_add(
+          &format, "c", GPU_COMP_U8, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
     }
     buffers->vert_buf = GPU_vertbuf_create_with_format_ex(&format, GPU_USAGE_STATIC);
   }
@@ -183,10 +186,12 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                   const int *vert_indices,
                                   int totvert,
                                   const float *vmask,
+                                  const MLoopCol *vcol,
                                   const int (*face_vert_indices)[3],
                                   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;
 
   {
@@ -216,6 +221,18 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
             }
           }
         }
+
+        if (vcol && show_vcol) {
+          for (uint i = 0; i < buffers->face_indices_len; i++) {
+            const MLoopTri *lt = &buffers->looptri[buffers->face_indices[i]];
+            for (int j = 0; j < 3; j++) {
+              const int loop_index = lt->tri[j];
+              const int vidx = face_vert_indices[i][j];
+              const uchar *elem = &vcol[loop_index].r;
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vidx, elem);
+            }
+          }
+        }
       }
       else {
         /* calculate normal for each polygon only once */
@@ -256,6 +273,12 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
             GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index, no);
             GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &fmask);
 
+            if (vcol && show_vcol) {
+              const uint loop_index = lt->tri[j];
+              const uchar *elem = &vcol[loop_index].r;
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, elem);
+            }
+
             vbo_index++;
           }
 
@@ -511,10 +534,12 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
                                   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;
   int i, j, k, x, y;
 
   const bool smooth = grid_flag_mats[grid_indices[0]].flag & ME_SMOOTH;
+  static char vcol[4] = {255, 255, 255, 255};
 
   /* Build VBO */
   const int has_mask = key->has_mask;
@@ -577,6 +602,11 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
               GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &fmask);
               empty_mask = empty_mask && (fmask == 0.0f);
             }
+
+            if (show_vcol) {
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, &vcol);
+            }
+
             vbo_index += 1;
           }
         }
@@ -623,6 +653,10 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
               GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 3, &fmask);
               empty_mask = empty_mask && (fmask == 0.0f);
             }
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 0, &vcol);
+            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 1, &vcol);
+            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);
             vbo_index += 4;
           }
         }
@@ -677,6 +711,7 @@ static void gpu_bmesh_vert_to_buffer_copy__gwn(BMVert *v,
                                                const float *fmask,
                                                const int cd_vert_mask_offset,
                                                const bool show_mask,
+                                               const bool show_vcol,
                                                bool *empty_mask)
 {
   if (!BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {
@@ -694,6 +729,11 @@ static void gpu_bmesh_vert_to_buffer_copy__gwn(BMVert *v,
       *empty_mask = *empty_mask && (effective_mask == 0.0f);
     }
 
+    if (show_vcol) {
+      static char vcol[4] = {255, 255, 255, 255};
+      GPU_vertbuf_attr_set(vert_buf, g_vbo_id.col, *v_index, &vcol);
+    }
+
     /* Assign index for use in the triangle index buffer */
     /* note: caller must set:  bm->elem_index_dirty |= BM_VERT; */
     BM_elem_index_set(v, (*v_index)); /* set_dirty! */
@@ -751,6 +791,7 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                    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;
   int tottri, totvert, maxvert = 0;
   bool empty_mask = true;
 
@@ -799,6 +840,7 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                            NULL,
                                            cd_vert_mask_offset,
                                            show_mask,
+                                           show_vcol,
                                            &empty_mask);
       }
 
@@ -810,6 +852,7 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                            NULL,
                                            cd_vert_mask_offset,
                                            show_mask,
+                                           show_vcol,
                                            &empty_mask);
       }
 
@@ -851,6 +894,7 @@ void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                                &fmask,
                                                cd_vert_mask_offset,
                                                show_mask,
+                                               show_vcol,
                                                &empty_mask);
           }
         }