Cycles: Add AttributeDescriptor

Adds a descriptor for attributes that can easily be passed around and extended
to contain more data. Will be used for attributes on subdivision meshes.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2110

6 files changed, 129 insertions, 125 deletions

diff --git a/intern/cycles/kernel/geom/geom_attribute.h b/intern/cycles/kernel/geom/geom_attribute.h
index 5d78cf8f9fc..e036c2752d7 100644
--- a/intern/cycles/kernel/geom/geom_attribute.h
+++ b/intern/cycles/kernel/geom/geom_attribute.h
@@ -43,12 +43,19 @@ ccl_device_inline uint attribute_primitive_type(KernelGlobals *kg, const ShaderD
 	}
 }
 
+ccl_device_inline AttributeDescriptor attribute_not_found()
+{
+	const AttributeDescriptor desc = {ATTR_ELEMENT_NONE, (NodeAttributeType)0, ATTR_STD_NOT_FOUND};
+	return desc;
+}
+
 /* Find attribute based on ID */
 
-ccl_device_inline int find_attribute(KernelGlobals *kg, const ShaderData *sd, uint id, AttributeElement *elem)
+ccl_device_inline AttributeDescriptor find_attribute(KernelGlobals *kg, const ShaderData *sd, uint id)
 {
-	if(ccl_fetch(sd, object) == PRIM_NONE)
-		return (int)ATTR_STD_NOT_FOUND;
+	if(ccl_fetch(sd, object) == PRIM_NONE) {
+		return attribute_not_found();
+	}
 
 	/* for SVM, find attribute by unique id */
 	uint attr_offset = ccl_fetch(sd, object)*kernel_data.bvh.attributes_map_stride;
@@ -57,31 +64,36 @@ ccl_device_inline int find_attribute(KernelGlobals *kg, const ShaderData *sd, ui
 	
 	while(attr_map.x != id) {
 		if(UNLIKELY(attr_map.x == ATTR_STD_NONE)) {
-			return ATTR_STD_NOT_FOUND;
+			return attribute_not_found();
 		}
 		attr_offset += ATTR_PRIM_TYPES;
 		attr_map = kernel_tex_fetch(__attributes_map, attr_offset);
 	}
 
-	*elem = (AttributeElement)attr_map.y;
+	AttributeDescriptor desc;
+	desc.element = (AttributeElement)attr_map.y;
 	
-	if(ccl_fetch(sd, prim) == PRIM_NONE && (AttributeElement)attr_map.y != ATTR_ELEMENT_MESH)
-		return ATTR_STD_NOT_FOUND;
+	if(ccl_fetch(sd, prim) == PRIM_NONE && desc.element != ATTR_ELEMENT_MESH) {
+		return attribute_not_found();
+	}
 
 	/* return result */
-	return (attr_map.y == ATTR_ELEMENT_NONE) ? (int)ATTR_STD_NOT_FOUND : (int)attr_map.z;
+	desc.offset = (attr_map.y == ATTR_ELEMENT_NONE) ? (int)ATTR_STD_NOT_FOUND : (int)attr_map.z;
+	desc.type = (NodeAttributeType)attr_map.w;
+
+	return desc;
 }
 
 /* Transform matrix attribute on meshes */
 
-ccl_device Transform primitive_attribute_matrix(KernelGlobals *kg, const ShaderData *sd, int offset)
+ccl_device Transform primitive_attribute_matrix(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc)
 {
 	Transform tfm;
 
-	tfm.x = kernel_tex_fetch(__attributes_float3, offset + 0);
-	tfm.y = kernel_tex_fetch(__attributes_float3, offset + 1);
-	tfm.z = kernel_tex_fetch(__attributes_float3, offset + 2);
-	tfm.w = kernel_tex_fetch(__attributes_float3, offset + 3);
+	tfm.x = kernel_tex_fetch(__attributes_float3, desc.offset + 0);
+	tfm.y = kernel_tex_fetch(__attributes_float3, desc.offset + 1);
+	tfm.z = kernel_tex_fetch(__attributes_float3, desc.offset + 2);
+	tfm.w = kernel_tex_fetch(__attributes_float3, desc.offset + 3);
 
 	return tfm;
 }
diff --git a/intern/cycles/kernel/geom/geom_curve.h b/intern/cycles/kernel/geom/geom_curve.h
index 292e1bfca0e..aa9cd295452 100644
--- a/intern/cycles/kernel/geom/geom_curve.h
+++ b/intern/cycles/kernel/geom/geom_curve.h
@@ -24,23 +24,23 @@ CCL_NAMESPACE_BEGIN
 
 /* Reading attributes on various curve elements */
 
-ccl_device float curve_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float *dx, float *dy)
+ccl_device float curve_attribute_float(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float *dx, float *dy)
 {
-	if(elem == ATTR_ELEMENT_CURVE) {
+	if(desc.element == ATTR_ELEMENT_CURVE) {
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = 0.0f;
 		if(dy) *dy = 0.0f;
 #endif
 
-		return kernel_tex_fetch(__attributes_float, offset + ccl_fetch(sd, prim));
+		return kernel_tex_fetch(__attributes_float, desc.offset + ccl_fetch(sd, prim));
 	}
-	else if(elem == ATTR_ELEMENT_CURVE_KEY || elem == ATTR_ELEMENT_CURVE_KEY_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_CURVE_KEY || desc.element == ATTR_ELEMENT_CURVE_KEY_MOTION) {
 		float4 curvedata = kernel_tex_fetch(__curves, ccl_fetch(sd, prim));
 		int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(ccl_fetch(sd, type));
 		int k1 = k0 + 1;
 
-		float f0 = kernel_tex_fetch(__attributes_float, offset + k0);
-		float f1 = kernel_tex_fetch(__attributes_float, offset + k1);
+		float f0 = kernel_tex_fetch(__attributes_float, desc.offset + k0);
+		float f1 = kernel_tex_fetch(__attributes_float, desc.offset + k1);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*(f1 - f0);
@@ -59,9 +59,9 @@ ccl_device float curve_attribute_float(KernelGlobals *kg, const ShaderData *sd,
 	}
 }
 
-ccl_device float3 curve_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float3 *dx, float3 *dy)
+ccl_device float3 curve_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
 {
-	if(elem == ATTR_ELEMENT_CURVE) {
+	if(desc.element == ATTR_ELEMENT_CURVE) {
 		/* idea: we can't derive any useful differentials here, but for tiled
 		 * mipmap image caching it would be useful to avoid reading the highest
 		 * detail level always. maybe a derivative based on the hair density
@@ -71,15 +71,15 @@ ccl_device float3 curve_attribute_float3(KernelGlobals *kg, const ShaderData *sd
 		if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
 #endif
 
-		return float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + ccl_fetch(sd, prim)));
+		return float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + ccl_fetch(sd, prim)));
 	}
-	else if(elem == ATTR_ELEMENT_CURVE_KEY || elem == ATTR_ELEMENT_CURVE_KEY_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_CURVE_KEY || desc.element == ATTR_ELEMENT_CURVE_KEY_MOTION) {
 		float4 curvedata = kernel_tex_fetch(__curves, ccl_fetch(sd, prim));
 		int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(ccl_fetch(sd, type));
 		int k1 = k0 + 1;
 
-		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + k0));
-		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + k1));
+		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + k0));
+		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + k1));
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*(f1 - f0);
diff --git a/intern/cycles/kernel/geom/geom_primitive.h b/intern/cycles/kernel/geom/geom_primitive.h
index b16f0c9a99b..4384c2093e9 100644
--- a/intern/cycles/kernel/geom/geom_primitive.h
+++ b/intern/cycles/kernel/geom/geom_primitive.h
@@ -25,24 +25,23 @@ CCL_NAMESPACE_BEGIN
 
 ccl_device_inline float primitive_attribute_float(KernelGlobals *kg,
                                                   const ShaderData *sd,
-                                                  AttributeElement elem,
-                                                  int offset,
+                                                  const AttributeDescriptor desc,
                                                   float *dx, float *dy)
 {
 	if(ccl_fetch(sd, type) & PRIMITIVE_ALL_TRIANGLE) {
 		if(subd_triangle_patch(kg, sd) == ~0)
-			return triangle_attribute_float(kg, sd, elem, offset, dx, dy);
+			return triangle_attribute_float(kg, sd, desc, dx, dy);
 		else
-			return subd_triangle_attribute_float(kg, sd, elem, offset, dx, dy);
+			return subd_triangle_attribute_float(kg, sd, desc, dx, dy);
 	}
 #ifdef __HAIR__
 	else if(ccl_fetch(sd, type) & PRIMITIVE_ALL_CURVE) {
-		return curve_attribute_float(kg, sd, elem, offset, dx, dy);
+		return curve_attribute_float(kg, sd, desc, dx, dy);
 	}
 #endif
 #ifdef __VOLUME__
-	else if(ccl_fetch(sd, object) != OBJECT_NONE && elem == ATTR_ELEMENT_VOXEL) {
-		return volume_attribute_float(kg, sd, elem, offset, dx, dy);
+	else if(ccl_fetch(sd, object) != OBJECT_NONE && desc.element == ATTR_ELEMENT_VOXEL) {
+		return volume_attribute_float(kg, sd, desc, dx, dy);
 	}
 #endif
 	else {
@@ -54,25 +53,23 @@ ccl_device_inline float primitive_attribute_float(KernelGlobals *kg,
 
 ccl_device_inline float3 primitive_attribute_float3(KernelGlobals *kg,
                                                     const ShaderData *sd,
-                                                    AttributeElement elem,
-                                                    int offset,
-                                                    float3 *dx,
-                                                    float3 *dy)
+                                                    const AttributeDescriptor desc,
+                                                    float3 *dx, float3 *dy)
 {
 	if(ccl_fetch(sd, type) & PRIMITIVE_ALL_TRIANGLE) {
 		if(subd_triangle_patch(kg, sd) == ~0)
-			return triangle_attribute_float3(kg, sd, elem, offset, dx, dy);
+			return triangle_attribute_float3(kg, sd, desc, dx, dy);
 		else
-			return subd_triangle_attribute_float3(kg, sd, elem, offset, dx, dy);
+			return subd_triangle_attribute_float3(kg, sd, desc, dx, dy);
 	}
 #ifdef __HAIR__
 	else if(ccl_fetch(sd, type) & PRIMITIVE_ALL_CURVE) {
-		return curve_attribute_float3(kg, sd, elem, offset, dx, dy);
+		return curve_attribute_float3(kg, sd, desc, dx, dy);
 	}
 #endif
 #ifdef __VOLUME__
-	else if(ccl_fetch(sd, object) != OBJECT_NONE && elem == ATTR_ELEMENT_VOXEL) {
-		return volume_attribute_float3(kg, sd, elem, offset, dx, dy);
+	else if(ccl_fetch(sd, object) != OBJECT_NONE && desc.element == ATTR_ELEMENT_VOXEL) {
+		return volume_attribute_float3(kg, sd, desc, dx, dy);
 	}
 #endif
 	else {
@@ -86,13 +83,12 @@ ccl_device_inline float3 primitive_attribute_float3(KernelGlobals *kg,
 
 ccl_device_inline float3 primitive_uv(KernelGlobals *kg, ShaderData *sd)
 {
-	AttributeElement elem_uv;
-	int offset_uv = find_attribute(kg, sd, ATTR_STD_UV, &elem_uv);
+	const AttributeDescriptor desc = find_attribute(kg, sd, ATTR_STD_UV);
 
-	if(offset_uv == ATTR_STD_NOT_FOUND)
+	if(desc.offset == ATTR_STD_NOT_FOUND)
 		return make_float3(0.0f, 0.0f, 0.0f);
 
-	float3 uv = primitive_attribute_float3(kg, sd, elem_uv, offset_uv, NULL, NULL);
+	float3 uv = primitive_attribute_float3(kg, sd, desc, NULL, NULL);
 	uv.z = 1.0f;
 	return uv;
 }
@@ -102,15 +98,14 @@ ccl_device_inline float3 primitive_uv(KernelGlobals *kg, ShaderData *sd)
 ccl_device bool primitive_ptex(KernelGlobals *kg, ShaderData *sd, float2 *uv, int *face_id)
 {
 	/* storing ptex data as attributes is not memory efficient but simple for tests */
-	AttributeElement elem_face_id, elem_uv;
-	int offset_face_id = find_attribute(kg, sd, ATTR_STD_PTEX_FACE_ID, &elem_face_id);
-	int offset_uv = find_attribute(kg, sd, ATTR_STD_PTEX_UV, &elem_uv);
+	const AttributeDescriptor desc_face_id = find_attribute(kg, sd, ATTR_STD_PTEX_FACE_ID);
+	const AttributeDescriptor desc_uv = find_attribute(kg, sd, ATTR_STD_PTEX_UV);
 
-	if(offset_face_id == ATTR_STD_NOT_FOUND || offset_uv == ATTR_STD_NOT_FOUND)
+	if(desc_face_id.offset == ATTR_STD_NOT_FOUND || desc_uv.offset == ATTR_STD_NOT_FOUND)
 		return false;
 
-	float3 uv3 = primitive_attribute_float3(kg, sd, elem_uv, offset_uv, NULL, NULL);
-	float face_id_f = primitive_attribute_float(kg, sd, elem_face_id, offset_face_id, NULL, NULL);
+	float3 uv3 = primitive_attribute_float3(kg, sd, desc_uv, NULL, NULL);
+	float face_id_f = primitive_attribute_float(kg, sd, desc_face_id, NULL, NULL);
 
 	*uv = make_float2(uv3.x, uv3.y);
 	*face_id = (int)face_id_f;
@@ -132,11 +127,10 @@ ccl_device float3 primitive_tangent(KernelGlobals *kg, ShaderData *sd)
 #endif
 
 	/* try to create spherical tangent from generated coordinates */
-	AttributeElement attr_elem;
-	int attr_offset = find_attribute(kg, sd, ATTR_STD_GENERATED, &attr_elem);
+	const AttributeDescriptor desc = find_attribute(kg, sd, ATTR_STD_GENERATED);
 
-	if(attr_offset != ATTR_STD_NOT_FOUND) {
-		float3 data = primitive_attribute_float3(kg, sd, attr_elem, attr_offset, NULL, NULL);
+	if(desc.offset != ATTR_STD_NOT_FOUND) {
+		float3 data = primitive_attribute_float3(kg, sd, desc, NULL, NULL);
 		data = make_float3(-(data.y - 0.5f), (data.x - 0.5f), 0.0f);
 		object_normal_transform(kg, sd, &data);
 		return cross(ccl_fetch(sd, N), normalize(cross(data, ccl_fetch(sd, N))));
@@ -173,19 +167,18 @@ ccl_device_inline float4 primitive_motion_vector(KernelGlobals *kg, ShaderData *
 	float3 motion_pre = center, motion_post = center;
 
 	/* deformation motion */
-	AttributeElement elem;
-	int offset = find_attribute(kg, sd, ATTR_STD_MOTION_VERTEX_POSITION, &elem);
+	AttributeDescriptor desc = find_attribute(kg, sd, ATTR_STD_MOTION_VERTEX_POSITION);
 
-	if(offset != ATTR_STD_NOT_FOUND) {
+	if(desc.offset != ATTR_STD_NOT_FOUND) {
 		/* get motion info */
 		int numverts, numkeys;
 		object_motion_info(kg, ccl_fetch(sd, object), NULL, &numverts, &numkeys);
 
 		/* lookup attributes */
-		int offset_next = (ccl_fetch(sd, type) & PRIMITIVE_ALL_TRIANGLE)? offset + numverts: offset + numkeys;
+		motion_pre = primitive_attribute_float3(kg, sd, desc, NULL, NULL);
 
-		motion_pre = primitive_attribute_float3(kg, sd, elem, offset, NULL, NULL);
-		motion_post = primitive_attribute_float3(kg, sd, elem, offset_next, NULL, NULL);
+		desc.offset += (ccl_fetch(sd, type) & PRIMITIVE_ALL_TRIANGLE)? numverts: numkeys;
+		motion_post = primitive_attribute_float3(kg, sd, desc, NULL, NULL);
 
 #ifdef __HAIR__
 		if(is_curve_primitive && (ccl_fetch(sd, flag) & SD_OBJECT_HAS_VERTEX_MOTION) == 0) {
diff --git a/intern/cycles/kernel/geom/geom_subd_triangle.h b/intern/cycles/kernel/geom/geom_subd_triangle.h
index bf9be182345..79a2ce5cc70 100644
--- a/intern/cycles/kernel/geom/geom_subd_triangle.h
+++ b/intern/cycles/kernel/geom/geom_subd_triangle.h
@@ -97,27 +97,27 @@ ccl_device_inline void subd_triangle_patch_corners(KernelGlobals *kg, int patch,
 
 /* Reading attributes on various subdivision triangle elements */
 
-ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float *dx, float *dy)
+ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float *dx, float *dy)
 {
 	int patch = subd_triangle_patch(kg, sd);
 
-	if(elem == ATTR_ELEMENT_FACE) {
+	if(desc.element == ATTR_ELEMENT_FACE) {
 		if(dx) *dx = 0.0f;
 		if(dy) *dy = 0.0f;
 
-		return kernel_tex_fetch(__attributes_float, offset + subd_triangle_patch_face(kg, patch));
+		return kernel_tex_fetch(__attributes_float, desc.offset + subd_triangle_patch_face(kg, patch));
 	}
-	else if(elem == ATTR_ELEMENT_VERTEX || elem == ATTR_ELEMENT_VERTEX_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_VERTEX || desc.element == ATTR_ELEMENT_VERTEX_MOTION) {
 		float2 uv[3];
 		subd_triangle_patch_uv(kg, sd, uv);
 		uint4 v = subd_triangle_patch_indices(kg, patch);
 
 		float a, b, c;
 
-		float f0 = kernel_tex_fetch(__attributes_float, offset + v.x);
-		float f1 = kernel_tex_fetch(__attributes_float, offset + v.y);
-		float f2 = kernel_tex_fetch(__attributes_float, offset + v.z);
-		float f3 = kernel_tex_fetch(__attributes_float, offset + v.w);
+		float f0 = kernel_tex_fetch(__attributes_float, desc.offset + v.x);
+		float f1 = kernel_tex_fetch(__attributes_float, desc.offset + v.y);
+		float f2 = kernel_tex_fetch(__attributes_float, desc.offset + v.z);
+		float f3 = kernel_tex_fetch(__attributes_float, desc.offset + v.w);
 
 		if(subd_triangle_patch_num_corners(kg, patch) != 4) {
 			f1 = (f1+f0)*0.5f;
@@ -135,7 +135,7 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 
 		return ccl_fetch(sd, u)*a + ccl_fetch(sd, v)*b + (1.0f - ccl_fetch(sd, u) - ccl_fetch(sd, v))*c;
 	}
-	else if(elem == ATTR_ELEMENT_CORNER) {
+	else if(desc.element == ATTR_ELEMENT_CORNER) {
 		int corners[4];
 		subd_triangle_patch_corners(kg, patch, corners);
 
@@ -144,10 +144,10 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 
 		float a, b, c;
 
-		float f0 = kernel_tex_fetch(__attributes_float, corners[0] + offset);
-		float f1 = kernel_tex_fetch(__attributes_float, corners[1] + offset);
-		float f2 = kernel_tex_fetch(__attributes_float, corners[2] + offset);
-		float f3 = kernel_tex_fetch(__attributes_float, corners[3] + offset);
+		float f0 = kernel_tex_fetch(__attributes_float, corners[0] + desc.offset);
+		float f1 = kernel_tex_fetch(__attributes_float, corners[1] + desc.offset);
+		float f2 = kernel_tex_fetch(__attributes_float, corners[2] + desc.offset);
+		float f3 = kernel_tex_fetch(__attributes_float, corners[3] + desc.offset);
 
 		if(subd_triangle_patch_num_corners(kg, patch) != 4) {
 			f1 = (f1+f0)*0.5f;
@@ -173,27 +173,27 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 	}
 }
 
-ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float3 *dx, float3 *dy)
+ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
 {
 	int patch = subd_triangle_patch(kg, sd);
 
-	if(elem == ATTR_ELEMENT_FACE) {
+	if(desc.element == ATTR_ELEMENT_FACE) {
 		if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
 		if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
 
-		return float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + subd_triangle_patch_face(kg, patch)));
+		return float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + subd_triangle_patch_face(kg, patch)));
 	}
-	else if(elem == ATTR_ELEMENT_VERTEX || elem == ATTR_ELEMENT_VERTEX_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_VERTEX || desc.element == ATTR_ELEMENT_VERTEX_MOTION) {
 		float2 uv[3];
 		subd_triangle_patch_uv(kg, sd, uv);
 		uint4 v = subd_triangle_patch_indices(kg, patch);
 
 		float3 a, b, c;
 
-		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + v.x));
-		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + v.y));
-		float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + v.z));
-		float3 f3 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + v.w));
+		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + v.x));
+		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + v.y));
+		float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + v.z));
+		float3 f3 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + v.w));
 
 		if(subd_triangle_patch_num_corners(kg, patch) != 4) {
 			f1 = (f1+f0)*0.5f;
@@ -211,7 +211,7 @@ ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const Shader
 
 		return ccl_fetch(sd, u)*a + ccl_fetch(sd, v)*b + (1.0f - ccl_fetch(sd, u) - ccl_fetch(sd, v))*c;
 	}
-	else if(elem == ATTR_ELEMENT_CORNER || elem == ATTR_ELEMENT_CORNER_BYTE) {
+	else if(desc.element == ATTR_ELEMENT_CORNER || desc.element == ATTR_ELEMENT_CORNER_BYTE) {
 		int corners[4];
 		subd_triangle_patch_corners(kg, patch, corners);
 
@@ -221,17 +221,17 @@ ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const Shader
 		float3 a, b, c;
 		float3 f0, f1, f2, f3;
 
-		if(elem == ATTR_ELEMENT_CORNER) {
-			f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[0] + offset));
-			f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[1] + offset));
-			f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[2] + offset));
-			f3 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[3] + offset));
+		if(desc.element == ATTR_ELEMENT_CORNER) {
+			f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[0] + desc.offset));
+			f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[1] + desc.offset));
+			f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[2] + desc.offset));
+			f3 = float4_to_float3(kernel_tex_fetch(__attributes_float3, corners[3] + desc.offset));
 		}
 		else {
-			f0 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[0] + offset));
-			f1 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[1] + offset));
-			f2 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[2] + offset));
-			f3 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[3] + offset));
+			f0 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[0] + desc.offset));
+			f1 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[1] + desc.offset));
+			f2 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[2] + desc.offset));
+			f3 = color_byte_to_float(kernel_tex_fetch(__attributes_uchar4, corners[3] + desc.offset));
 		}
 
 		if(subd_triangle_patch_num_corners(kg, patch) != 4) {
diff --git a/intern/cycles/kernel/geom/geom_triangle.h b/intern/cycles/kernel/geom/geom_triangle.h
index 0c2351e1d1b..d3289d6572c 100644
--- a/intern/cycles/kernel/geom/geom_triangle.h
+++ b/intern/cycles/kernel/geom/geom_triangle.h
@@ -105,20 +105,20 @@ ccl_device_inline void triangle_dPdudv(KernelGlobals *kg, int prim, ccl_addr_spa
 
 /* Reading attributes on various triangle elements */
 
-ccl_device float triangle_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float *dx, float *dy)
+ccl_device float triangle_attribute_float(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float *dx, float *dy)
 {
-	if(elem == ATTR_ELEMENT_FACE) {
+	if(desc.element == ATTR_ELEMENT_FACE) {
 		if(dx) *dx = 0.0f;
 		if(dy) *dy = 0.0f;
 
-		return kernel_tex_fetch(__attributes_float, offset + ccl_fetch(sd, prim));
+		return kernel_tex_fetch(__attributes_float, desc.offset + ccl_fetch(sd, prim));
 	}
-	else if(elem == ATTR_ELEMENT_VERTEX || elem == ATTR_ELEMENT_VERTEX_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_VERTEX || desc.element == ATTR_ELEMENT_VERTEX_MOTION) {
 		uint4 tri_vindex = kernel_tex_fetch(__tri_vindex, ccl_fetch(sd, prim));
 
-		float f0 = kernel_tex_fetch(__attributes_float, offset + tri_vindex.x);
-		float f1 = kernel_tex_fetch(__attributes_float, offset + tri_vindex.y);
-		float f2 = kernel_tex_fetch(__attributes_float, offset + tri_vindex.z);
+		float f0 = kernel_tex_fetch(__attributes_float, desc.offset + tri_vindex.x);
+		float f1 = kernel_tex_fetch(__attributes_float, desc.offset + tri_vindex.y);
+		float f2 = kernel_tex_fetch(__attributes_float, desc.offset + tri_vindex.z);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*f0 + ccl_fetch(sd, dv).dx*f1 - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*f2;
@@ -127,8 +127,8 @@ ccl_device float triangle_attribute_float(KernelGlobals *kg, const ShaderData *s
 
 		return ccl_fetch(sd, u)*f0 + ccl_fetch(sd, v)*f1 + (1.0f - ccl_fetch(sd, u) - ccl_fetch(sd, v))*f2;
 	}
-	else if(elem == ATTR_ELEMENT_CORNER) {
-		int tri = offset + ccl_fetch(sd, prim)*3;
+	else if(desc.element == ATTR_ELEMENT_CORNER) {
+		int tri = desc.offset + ccl_fetch(sd, prim)*3;
 		float f0 = kernel_tex_fetch(__attributes_float, tri + 0);
 		float f1 = kernel_tex_fetch(__attributes_float, tri + 1);
 		float f2 = kernel_tex_fetch(__attributes_float, tri + 2);
@@ -148,20 +148,20 @@ ccl_device float triangle_attribute_float(KernelGlobals *kg, const ShaderData *s
 	}
 }
 
-ccl_device float3 triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int offset, float3 *dx, float3 *dy)
+ccl_device float3 triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
 {
-	if(elem == ATTR_ELEMENT_FACE) {
+	if(desc.element == ATTR_ELEMENT_FACE) {
 		if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
 		if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
 
-		return float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + ccl_fetch(sd, prim)));
+		return float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + ccl_fetch(sd, prim)));
 	}
-	else if(elem == ATTR_ELEMENT_VERTEX || elem == ATTR_ELEMENT_VERTEX_MOTION) {
+	else if(desc.element == ATTR_ELEMENT_VERTEX || desc.element == ATTR_ELEMENT_VERTEX_MOTION) {
 		uint4 tri_vindex = kernel_tex_fetch(__tri_vindex, ccl_fetch(sd, prim));
 
-		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + tri_vindex.x));
-		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + tri_vindex.y));
-		float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, offset + tri_vindex.z));
+		float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + tri_vindex.x));
+		float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + tri_vindex.y));
+		float3 f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + tri_vindex.z));
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*f0 + ccl_fetch(sd, dv).dx*f1 - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*f2;
@@ -170,11 +170,11 @@ ccl_device float3 triangle_attribute_float3(KernelGlobals *kg, const ShaderData
 
 		return ccl_fetch(sd, u)*f0 + ccl_fetch(sd, v)*f1 + (1.0f - ccl_fetch(sd, u) - ccl_fetch(sd, v))*f2;
 	}
-	else if(elem == ATTR_ELEMENT_CORNER || elem == ATTR_ELEMENT_CORNER_BYTE) {
-		int tri = offset + ccl_fetch(sd, prim)*3;
+	else if(desc.element == ATTR_ELEMENT_CORNER || desc.element == ATTR_ELEMENT_CORNER_BYTE) {
+		int tri = desc.offset + ccl_fetch(sd, prim)*3;
 		float3 f0, f1, f2;
 
-		if(elem == ATTR_ELEMENT_CORNER) {
+		if(desc.element == ATTR_ELEMENT_CORNER) {
 			f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 0));
 			f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 1));
 			f2 = float4_to_float3(kernel_tex_fetch(__attributes_float3, tri + 2));
diff --git a/intern/cycles/kernel/geom/geom_volume.h b/intern/cycles/kernel/geom/geom_volume.h
index 7c8182bc430..efe540a8518 100644
--- a/intern/cycles/kernel/geom/geom_volume.h
+++ b/intern/cycles/kernel/geom/geom_volume.h
@@ -50,36 +50,35 @@ ccl_device_inline float3 volume_normalized_position(KernelGlobals *kg,
 {
 	/* todo: optimize this so it's just a single matrix multiplication when
 	 * possible (not motion blur), or perhaps even just translation + scale */
-	AttributeElement attr_elem;
-	int attr_offset = find_attribute(kg, sd, ATTR_STD_GENERATED_TRANSFORM, &attr_elem);
+	const AttributeDescriptor desc = find_attribute(kg, sd, ATTR_STD_GENERATED_TRANSFORM);
 
 	object_inverse_position_transform(kg, sd, &P);
 
-	if(attr_offset != ATTR_STD_NOT_FOUND) {
-		Transform tfm = primitive_attribute_matrix(kg, sd, attr_offset);
+	if(desc.offset != ATTR_STD_NOT_FOUND) {
+		Transform tfm = primitive_attribute_matrix(kg, sd, desc);
 		P = transform_point(&tfm, P);
 	}
 
 	return P;
 }
 
-ccl_device float volume_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int id, float *dx, float *dy)
+ccl_device float volume_attribute_float(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float *dx, float *dy)
 {
 	float3 P = volume_normalized_position(kg, sd, sd->P);
 #ifdef __KERNEL_GPU__
 #  if __CUDA_ARCH__ >= 300
-	CUtexObject tex = kernel_tex_fetch(__bindless_mapping, id);
+	CUtexObject tex = kernel_tex_fetch(__bindless_mapping, desc.offset);
 	float f = kernel_tex_image_interp_3d_float(tex, P.x, P.y, P.z);
 	float4 r = make_float4(f, f, f, 1.0);
 #  else
-	float4 r = volume_image_texture_3d(id, P.x, P.y, P.z);
+	float4 r = volume_image_texture_3d(desc.offset, P.x, P.y, P.z);
 #  endif
 #else
 	float4 r;
 	if(sd->flag & SD_VOLUME_CUBIC)
-		r = kernel_tex_image_interp_3d_ex(id, P.x, P.y, P.z, INTERPOLATION_CUBIC);
+		r = kernel_tex_image_interp_3d_ex(desc.offset, P.x, P.y, P.z, INTERPOLATION_CUBIC);
 	else
-		r = kernel_tex_image_interp_3d(id, P.x, P.y, P.z);
+		r = kernel_tex_image_interp_3d(desc.offset, P.x, P.y, P.z);
 #endif
 
 	if(dx) *dx = 0.0f;
@@ -88,22 +87,22 @@ ccl_device float volume_attribute_float(KernelGlobals *kg, const ShaderData *sd,
 	return average(float4_to_float3(r));
 }
 
-ccl_device float3 volume_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int id, float3 *dx, float3 *dy)
+ccl_device float3 volume_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
 {
 	float3 P = volume_normalized_position(kg, sd, sd->P);
 #ifdef __KERNEL_GPU__
 #  if __CUDA_ARCH__ >= 300
-	CUtexObject tex = kernel_tex_fetch(__bindless_mapping, id);
+	CUtexObject tex = kernel_tex_fetch(__bindless_mapping, desc.offset);
 	float4 r = kernel_tex_image_interp_3d_float4(tex, P.x, P.y, P.z);
 #  else
-	float4 r = volume_image_texture_3d(id, P.x, P.y, P.z);
+	float4 r = volume_image_texture_3d(desc.offset, P.x, P.y, P.z);
 #  endif
 #else
 	float4 r;
 	if(sd->flag & SD_VOLUME_CUBIC)
-		r = kernel_tex_image_interp_3d_ex(id, P.x, P.y, P.z, INTERPOLATION_CUBIC);
+		r = kernel_tex_image_interp_3d_ex(desc.offset, P.x, P.y, P.z, INTERPOLATION_CUBIC);
 	else
-		r = kernel_tex_image_interp_3d(id, P.x, P.y, P.z);
+		r = kernel_tex_image_interp_3d(desc.offset, P.x, P.y, P.z);
 #endif
 
 	if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);