DRW: Use USHORT for vertex color and upload them in linear color to the GPU

This way we remove the need for the srgb boolean uniform and a lot of code complexity. However, mesh update is going to be a bit slower.

I did not benchmark the performance impact.

This also fix a typo in draw_cache_impl_particles.c and fix hair not using vertex color in workbench.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6610

2 files changed, 18 insertions, 48 deletions

diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index 2c74afd2d8e..bf7b1908321 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -116,7 +116,7 @@ void gpu_pbvh_init()
     g_vbo_id.msk = GPU_vertformat_attr_add(
         &g_vbo_id.format, "msk", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
     g_vbo_id.col = GPU_vertformat_attr_add(
-        &g_vbo_id.format, "ac", GPU_COMP_U8, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
+        &g_vbo_id.format, "ac", GPU_COMP_U16, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
   }
 }
 
@@ -240,8 +240,13 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
             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);
+              const MLoopCol *mcol = &vcol[loop_index];
+              ushort scol[4];
+              scol[0] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->r]);
+              scol[1] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->g]);
+              scol[2] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->b]);
+              scol[3] = unit_float_to_ushort_clamp(mcol->a * (1.0f / 255.0f));
+              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vidx, scol);
             }
           }
         }
@@ -289,8 +294,13 @@ void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
 
             if (show_vcol) {
               const uint loop_index = lt->tri[j];
-              const uchar *elem = &vcol[loop_index].r;
-              memcpy(GPU_vertbuf_raw_step(&col_step), elem, sizeof(uchar) * 4);
+              const MLoopCol *mcol = &vcol[loop_index];
+              ushort scol[4];
+              scol[0] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->r]);
+              scol[1] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->g]);
+              scol[2] = unit_float_to_ushort_clamp(BLI_color_from_srgb_table[mcol->b]);
+              scol[3] = unit_float_to_ushort_clamp(mcol->a * (1.0f / 255.0f));
+              memcpy(GPU_vertbuf_raw_step(&col_step), scol, sizeof(scol));
             }
           }
         }
@@ -654,7 +664,7 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
             }
 
             if (show_vcol) {
-              char vcol[4] = {255, 255, 255, 255};
+              ushort vcol[4] = {USHRT_MAX, USHRT_MAX, USHRT_MAX, USHRT_MAX};
               GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, &vcol);
             }
 
@@ -705,7 +715,7 @@ void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
               empty_mask = empty_mask && (fmask == 0.0f);
             }
 
-            char vcol[4] = {255, 255, 255, 255};
+            ushort vcol[4] = {USHRT_MAX, USHRT_MAX, USHRT_MAX, USHRT_MAX};
             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);
@@ -781,7 +791,7 @@ static void gpu_bmesh_vert_to_buffer_copy(BMVert *v,
   }
 
   if (show_vcol) {
-    static char vcol[4] = {255, 255, 255, 255};
+    ushort vcol[4] = {USHRT_MAX, USHRT_MAX, USHRT_MAX, USHRT_MAX};
     GPU_vertbuf_attr_set(vert_buf, g_vbo_id.col, v_index, &vcol);
   }
 }
diff --git a/source/blender/gpu/intern/gpu_codegen.c b/source/blender/gpu/intern/gpu_codegen.c
index 5a5c3ace552..a7dd34a5f96 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -1042,12 +1042,6 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
                              input->attr_id,
                              attr_prefix_get(input->attr_type),
                              attr_safe_name);
-          /* Auto attribute can be vertex color byte buffer.
-           * We need to know and convert them to linear space in VS. */
-          if (input->attr_type == CD_AUTO_FROM_NAME) {
-            BLI_dynstr_appendf(ds, "uniform bool ba%s;\n", attr_safe_name);
-            BLI_dynstr_appendf(ds, "#define att%d_is_srgb ba%s\n", input->attr_id, attr_safe_name);
-          }
         }
         BLI_dynstr_appendf(ds,
                            "out %s var%d%s;\n",
@@ -1101,24 +1095,6 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
 
   BLI_dynstr_append(ds, use_geom ? "RESOURCE_ID_VARYING_GEOM\n" : "RESOURCE_ID_VARYING\n");
 
-  BLI_dynstr_append(ds,
-                    "#define USE_ATTR\n"
-                    "vec3 srgb_to_linear_attr(vec3 c) {\n"
-                    "\tc = max(c, vec3(0.0));\n"
-                    "\tvec3 c1 = c * (1.0 / 12.92);\n"
-                    "\tvec3 c2 = pow((c + 0.055) * (1.0 / 1.055), vec3(2.4));\n"
-                    "\treturn mix(c1, c2, step(vec3(0.04045), c));\n"
-                    "}\n\n");
-
-  BLI_dynstr_append(ds,
-                    "vec4 srgba_to_linear_attr(vec4 c) {\n"
-                    "\tc = max(c, vec4(0.0));\n"
-                    "\tvec4 c1 = c * (1.0 / 12.92);\n"
-                    "\tvec4 c2 = pow((c + 0.055) * (1.0 / 1.055), vec4(2.4));\n"
-                    "\tvec4 final = mix(c1, c2, step(vec4(0.04045), c));"
-                    "\treturn vec4(final.xyz, c.a);\n"
-                    "}\n\n");
-
   /* Prototype because defined later. */
   BLI_dynstr_append(ds,
                     "vec2 hair_get_customdata_vec2(const samplerBuffer);\n"
@@ -1224,22 +1200,6 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
                              input->attr_id,
                              use_geom ? "g" : "");
         }
-        else if (input->attr_type == CD_MCOL) {
-          BLI_dynstr_appendf(ds,
-                             "\tvar%d%s = srgba_to_linear_attr(att%d);\n",
-                             input->attr_id,
-                             use_geom ? "g" : "",
-                             input->attr_id);
-        }
-        else if (input->attr_type == CD_AUTO_FROM_NAME) {
-          BLI_dynstr_appendf(ds,
-                             "\tvar%d%s = (att%d_is_srgb) ? srgb_to_linear_attr(att%d) : att%d;\n",
-                             input->attr_id,
-                             use_geom ? "g" : "",
-                             input->attr_id,
-                             input->attr_id,
-                             input->attr_id);
-        }
         else {
           BLI_dynstr_appendf(
               ds, "\tvar%d%s = att%d;\n", input->attr_id, use_geom ? "g" : "", input->attr_id);