Shading: Add Vertex Color node.

This patch adds a new Vertex Color node. The node also returns the alpha
of the vertex color layer as an output.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D5767

4 files changed, 23 insertions, 1 deletions

diff --git a/source/blender/gpu/CMakeLists.txt b/source/blender/gpu/CMakeLists.txt
index aea96dac2e3..8d2355ff5ac 100644
--- a/source/blender/gpu/CMakeLists.txt
+++ b/source/blender/gpu/CMakeLists.txt
@@ -313,6 +313,7 @@ data_to_c_simple(shaders/material/gpu_shader_material_vector_curves.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_vector_displacement.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_vector_math.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_velvet.glsl SRC)
+data_to_c_simple(shaders/material/gpu_shader_material_vertex_color.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_volume_absorption.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_volume_info.glsl SRC)
 data_to_c_simple(shaders/material/gpu_shader_material_volume_principled.glsl SRC)
diff --git a/source/blender/gpu/intern/gpu_codegen.c b/source/blender/gpu/intern/gpu_codegen.c
index 8b68bcd5889..242b0ed2e31 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -1080,6 +1080,15 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
                     "\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"
@@ -1184,7 +1193,7 @@ static char *code_generate_vertex(ListBase *nodes, const char *vert_code, bool u
         }
         else if (input->attr_type == CD_MCOL) {
           BLI_dynstr_appendf(ds,
-                             "\tvar%d%s = srgb_to_linear_attr(att%d);\n",
+                             "\tvar%d%s = srgba_to_linear_attr(att%d);\n",
                              input->attr_id,
                              use_geom ? "g" : "",
                              input->attr_id);
diff --git a/source/blender/gpu/intern/gpu_material_library.h b/source/blender/gpu/intern/gpu_material_library.h
index 06544d27af9..3a38eb5c600 100644
--- a/source/blender/gpu/intern/gpu_material_library.h
+++ b/source/blender/gpu/intern/gpu_material_library.h
@@ -114,6 +114,7 @@ extern char datatoc_gpu_shader_material_vector_curves_glsl[];
 extern char datatoc_gpu_shader_material_vector_displacement_glsl[];
 extern char datatoc_gpu_shader_material_vector_math_glsl[];
 extern char datatoc_gpu_shader_material_velvet_glsl[];
+extern char datatoc_gpu_shader_material_vertex_color_glsl[];
 extern char datatoc_gpu_shader_material_volume_absorption_glsl[];
 extern char datatoc_gpu_shader_material_volume_info_glsl[];
 extern char datatoc_gpu_shader_material_volume_principled_glsl[];
@@ -527,6 +528,11 @@ static GPUMaterialLibrary gpu_shader_material_velvet_library = {
     .dependencies = {&gpu_shader_material_diffuse_library, NULL},
 };
 
+static GPUMaterialLibrary gpu_shader_material_vertex_color_library = {
+    .code = datatoc_gpu_shader_material_vertex_color_glsl,
+    .dependencies = {NULL},
+};
+
 static GPUMaterialLibrary gpu_shader_material_volume_absorption_library = {
     .code = datatoc_gpu_shader_material_volume_absorption_glsl,
     .dependencies = {NULL},
@@ -638,6 +644,7 @@ static GPUMaterialLibrary *gpu_material_libraries[] = {
     &gpu_shader_material_vector_displacement_library,
     &gpu_shader_material_vector_math_library,
     &gpu_shader_material_velvet_library,
+    &gpu_shader_material_vertex_color_library,
     &gpu_shader_material_volume_absorption_library,
     &gpu_shader_material_volume_info_library,
     &gpu_shader_material_volume_principled_library,
diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_vertex_color.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_vertex_color.glsl
new file mode 100644
index 00000000000..551b838daf8
--- /dev/null
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_vertex_color.glsl
@@ -0,0 +1,5 @@
+void node_vertex_color(vec4 vertexColor, out vec4 outColor, out float outAlpha)
+{
+  outColor = vertexColor;
+  outAlpha = vertexColor.a;
+}