Support Vertex Color in GLSL viewport for Cycles

The title says it all actually.

Added special custom data type, because we don't know in advance
whether we're referencing UV or Color layer. Also made it so vertex
attributes are normalized.

TODO: Border render in viewport ignores the normalization of the
attribute array for some reason, will be looked into still.

Reviewers: mont29, brecht, campbellbarton

Reviewed By: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D2022

source/blender/blenkernel/intern/DerivedMesh.c

@@ -3629,12 +3629,41 @@ void DM_vertex_attributes_from_gpu(DerivedMesh *dm, GPUVertexAttribs *gattribs,
 		dm->calcLoopTangents(dm, false, (const char (*)[MAX_NAME])tangent_names, tangent_names_count);
 
 	for (b = 0; b < gattribs->totlayer; b++) {
-		if (gattribs->layer[b].type == CD_MTFACE) {
+		int type = gattribs->layer[b].type;
+		layer = -1;
+		if (type == CD_AUTO_FROM_NAME) {
+			/* We need to deduct what exact layer is used.
+			 *
+			 * We do it based on the specified name.
+			 */
+			if (gattribs->layer[b].name[0]) {
+				layer = CustomData_get_named_layer_index(&dm->loopData, CD_TANGENT, gattribs->layer[b].name);
+				type = CD_TANGENT;
+				if (layer == -1) {
+					layer = CustomData_get_named_layer_index(ldata, CD_MLOOPCOL, gattribs->layer[b].name);
+					type = CD_MCOL;
+				}
+				if (layer == -1) {
+					layer = CustomData_get_named_layer_index(ldata, CD_MLOOPUV, gattribs->layer[b].name);
+					type = CD_MTFACE;
+				}
+				if (layer == -1) {
+					continue;
+				}
+			}
+			else {
+				/* Fall back to the UV layer, which matches old behavior. */
+				type = CD_MTFACE;
+			}
+		}
+		if (type == CD_MTFACE) {
 			/* uv coordinates */
-			if (gattribs->layer[b].name[0])
-				layer = CustomData_get_named_layer_index(ldata, CD_MLOOPUV, gattribs->layer[b].name);
-			else
-				layer = CustomData_get_active_layer_index(ldata, CD_MLOOPUV);
+			if (layer == -1) {
+				if (gattribs->layer[b].name[0])
+					layer = CustomData_get_named_layer_index(ldata, CD_MLOOPUV, gattribs->layer[b].name);
+				else
+					layer = CustomData_get_active_layer_index(ldata, CD_MLOOPUV);
+			}
 
 			a = attribs->tottface++;
 
@@ -3650,11 +3679,13 @@ void DM_vertex_attributes_from_gpu(DerivedMesh *dm, GPUVertexAttribs *gattribs,
 			attribs->tface[a].gl_index = gattribs->layer[b].glindex;
 			attribs->tface[a].gl_texco = gattribs->layer[b].gltexco;
 		}
-		else if (gattribs->layer[b].type == CD_MCOL) {
-			if (gattribs->layer[b].name[0])
-				layer = CustomData_get_named_layer_index(ldata, CD_MLOOPCOL, gattribs->layer[b].name);
-			else
-				layer = CustomData_get_active_layer_index(ldata, CD_MLOOPCOL);
+		else if (type == CD_MCOL) {
+			if (layer == -1) {
+				if (gattribs->layer[b].name[0])
+					layer = CustomData_get_named_layer_index(ldata, CD_MLOOPCOL, gattribs->layer[b].name);
+				else
+					layer = CustomData_get_active_layer_index(ldata, CD_MLOOPCOL);
+			}
 
 			a = attribs->totmcol++;
 
@@ -3670,13 +3701,14 @@ void DM_vertex_attributes_from_gpu(DerivedMesh *dm, GPUVertexAttribs *gattribs,
 
 			attribs->mcol[a].gl_index = gattribs->layer[b].glindex;
 		}
-		else if (gattribs->layer[b].type == CD_TANGENT) {
+		else if (type == CD_TANGENT) {
 			/* note, even with 'is_editmesh' this uses the derived-meshes loop data */
-
-			if (gattribs->layer[b].name[0])
-				layer = CustomData_get_named_layer_index(&dm->loopData, CD_TANGENT, gattribs->layer[b].name);
-			else
-				layer = CustomData_get_active_layer_index(&dm->loopData, CD_TANGENT);
+			if (layer == -1) {
+				if (gattribs->layer[b].name[0])
+					layer = CustomData_get_named_layer_index(&dm->loopData, CD_TANGENT, gattribs->layer[b].name);
+				else
+					layer = CustomData_get_active_layer_index(&dm->loopData, CD_TANGENT);
+			}
 
 			a = attribs->tottang++;
 
@@ -3691,9 +3723,11 @@ void DM_vertex_attributes_from_gpu(DerivedMesh *dm, GPUVertexAttribs *gattribs,
 
 			attribs->tang[a].gl_index = gattribs->layer[b].glindex;
 		}
-		else if (gattribs->layer[b].type == CD_ORCO) {
+		else if (type == CD_ORCO) {
 			/* original coordinates */
-			layer = CustomData_get_layer_index(vdata, CD_ORCO);
+			if (layer == -1) {
+				layer = CustomData_get_layer_index(vdata, CD_ORCO);
+			}
 			attribs->totorco = 1;
 
 			if (layer != -1) {

source/blender/gpu/intern/gpu_buffers.c

@@ -823,7 +823,7 @@ void GPU_interleaved_attrib_setup(GPUBuffer *buffer, GPUAttrib data[], int numda
 	for (i = 0; i < numdata; i++) {
 		glEnableVertexAttribArray(data[i].index);
 		glVertexAttribPointer(data[i].index, data[i].size, data[i].type,
-		                         GL_FALSE, elementsize, BUFFER_OFFSET(offset));
+		                         GL_TRUE, elementsize, BUFFER_OFFSET(offset));
 		offset += data[i].size * GPU_typesize(data[i].type);
 		
 		attribData[i].index = data[i].index;

source/blender/gpu/shaders/gpu_shader_material.glsl

@@ -2573,11 +2573,11 @@ void node_gamma(vec4 col, float gamma, out vec4 outcol)
 
 /* geometry */
 
-void node_attribute(vec3 attr_uv, out vec4 outcol, out vec3 outvec, out float outf)
+void node_attribute(vec3 attr, out vec4 outcol, out vec3 outvec, out float outf)
 {
-	outcol = vec4(attr_uv, 1.0);
-	outvec = attr_uv;
-	outf = (attr_uv.x + attr_uv.y + attr_uv.z)/3.0;
+	outcol = vec4(attr, 1.0);
+	outvec = attr;
+	outf = (attr.x + attr.y + attr.z)/3.0;
 }
 
 void node_uvmap(vec3 attr_uv, out vec3 outvec)

source/blender/makesdna/DNA_customdata_types.h

@@ -75,6 +75,12 @@ typedef struct CustomData {
 
 /* CustomData.type */
 typedef enum CustomDataType {
+	/* Used by GLSL attributes in the cases when we need a delayed CD type
+	 * assignment (in the cases when we don't know in advance which layer
+	 * we are addressing).
+	 */
+	CD_AUTO_FROM_NAME   = -1,
+
 	CD_MVERT            = 0,
 #ifdef DNA_DEPRECATED
 	CD_MSTICKY          = 1,  /* DEPRECATED */

source/blender/nodes/shader/nodes/node_shader_attribute.c

@@ -45,9 +45,9 @@ static void node_shader_init_attribute(bNodeTree *UNUSED(ntree), bNode *node)
 static int node_shader_gpu_attribute(GPUMaterial *mat, bNode *node, bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
 {
 	NodeShaderAttribute *attr = node->storage;
-	GPUNodeLink *mtface = GPU_attribute(CD_MTFACE, attr->name);
+	GPUNodeLink *cd_attr = GPU_attribute(CD_AUTO_FROM_NAME, attr->name);
 
-	return GPU_stack_link(mat, "node_attribute", in, out, mtface);
+	return GPU_stack_link(mat, "node_attribute", in, out, cd_attr);
 }
 
 /* node type definition */