Cycles microdisplacement: Support for Catmull-Clark subdivision via OpenSubdiv

Enables Catmull-Clark subdivision meshes with support for creases and attribute
subdivision. Still waiting on OpenSubdiv to fully support face varying
interpolation for subdividing uv coordinates tho. Also there may be some
inconsistencies with Blender's subdivision which will be resolved at a
later time.

Code for reading patch tables and creating patch maps is borrowed
from OpenSubdiv.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2111

1 files changed, 115 insertions, 28 deletions

diff --git a/intern/cycles/kernel/geom/geom_subd_triangle.h b/intern/cycles/kernel/geom/geom_subd_triangle.h
index 79a2ce5cc70..fccacf435f9 100644
--- a/intern/cycles/kernel/geom/geom_subd_triangle.h
+++ b/intern/cycles/kernel/geom/geom_subd_triangle.h
@@ -97,11 +97,54 @@ 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, const AttributeDescriptor desc, float *dx, float *dy)
+ccl_device_noinline 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(desc.element == ATTR_ELEMENT_FACE) {
+	if(desc.flags & ATTR_SUBDIVIDED) {
+		float2 uv[3];
+		subd_triangle_patch_uv(kg, sd, uv);
+
+		float2 dpdu = uv[0] - uv[2];
+		float2 dpdv = uv[1] - uv[2];
+
+		/* p is [s, t] */
+		float2 p = dpdu * ccl_fetch(sd, u) + dpdv * ccl_fetch(sd, v) + uv[2];
+
+		float a, dads, dadt;
+		a = patch_eval_float(kg, sd, desc.offset, patch, p.x, p.y, 0, &dads, &dadt);
+
+#ifdef __RAY_DIFFERENTIALS__
+		if(dx || dy) {
+			float dsdu = dpdu.x;
+			float dtdu = dpdu.y;
+			float dsdv = dpdv.x;
+			float dtdv = dpdv.y;
+
+			if(dx) {
+				float dudx = ccl_fetch(sd, du).dx;
+				float dvdx = ccl_fetch(sd, dv).dx;
+
+				float dsdx = dsdu*dudx + dsdv*dvdx;
+				float dtdx = dtdu*dudx + dtdv*dvdx;
+
+				*dx = dads*dsdx + dadt*dtdx;
+			}
+			if(dy) {
+				float dudy = ccl_fetch(sd, du).dy;
+				float dvdy = ccl_fetch(sd, dv).dy;
+
+				float dsdy = dsdu*dudy + dsdv*dvdy;
+				float dtdy = dtdu*dudy + dtdv*dvdy;
+
+				*dy = dads*dsdy + dadt*dtdy;
+			}
+		}
+#endif
+
+		return a;
+	}
+	else if(desc.element == ATTR_ELEMENT_FACE) {
 		if(dx) *dx = 0.0f;
 		if(dy) *dy = 0.0f;
 
@@ -110,9 +153,8 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 	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;
+		uint4 v = subd_triangle_patch_indices(kg, patch);
 
 		float f0 = kernel_tex_fetch(__attributes_float, desc.offset + v.x);
 		float f1 = kernel_tex_fetch(__attributes_float, desc.offset + v.y);
@@ -124,9 +166,9 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 			f3 = (f3+f0)*0.5f;
 		}
 
-		a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
-		b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
-		c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
+		float a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
+		float b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
+		float c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*a + ccl_fetch(sd, dv).dx*b - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*c;
@@ -136,13 +178,11 @@ 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(desc.element == ATTR_ELEMENT_CORNER) {
-		int corners[4];
-		subd_triangle_patch_corners(kg, patch, corners);
-
 		float2 uv[3];
 		subd_triangle_patch_uv(kg, sd, uv);
 
-		float a, b, c;
+		int corners[4];
+		subd_triangle_patch_corners(kg, patch, corners);
 
 		float f0 = kernel_tex_fetch(__attributes_float, corners[0] + desc.offset);
 		float f1 = kernel_tex_fetch(__attributes_float, corners[1] + desc.offset);
@@ -154,9 +194,9 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 			f3 = (f3+f0)*0.5f;
 		}
 
-		a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
-		b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
-		c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
+		float a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
+		float b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
+		float c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*a + ccl_fetch(sd, dv).dx*b - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*c;
@@ -173,11 +213,60 @@ ccl_device float subd_triangle_attribute_float(KernelGlobals *kg, const ShaderDa
 	}
 }
 
-ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
+ccl_device_noinline 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(desc.element == ATTR_ELEMENT_FACE) {
+	if(desc.flags & ATTR_SUBDIVIDED) {
+		float2 uv[3];
+		subd_triangle_patch_uv(kg, sd, uv);
+
+		float2 dpdu = uv[0] - uv[2];
+		float2 dpdv = uv[1] - uv[2];
+
+		/* p is [s, t] */
+		float2 p = dpdu * ccl_fetch(sd, u) + dpdv * ccl_fetch(sd, v) + uv[2];
+
+		float3 a, dads, dadt;
+
+		if(desc.element == ATTR_ELEMENT_CORNER_BYTE) {
+			a = patch_eval_uchar4(kg, sd, desc.offset, patch, p.x, p.y, 0, &dads, &dadt);
+		}
+		else {
+			a = patch_eval_float3(kg, sd, desc.offset, patch, p.x, p.y, 0, &dads, &dadt);
+		}
+
+#ifdef __RAY_DIFFERENTIALS__
+		if(dx || dy) {
+			float dsdu = dpdu.x;
+			float dtdu = dpdu.y;
+			float dsdv = dpdv.x;
+			float dtdv = dpdv.y;
+
+			if(dx) {
+				float dudx = ccl_fetch(sd, du).dx;
+				float dvdx = ccl_fetch(sd, dv).dx;
+
+				float dsdx = dsdu*dudx + dsdv*dvdx;
+				float dtdx = dtdu*dudx + dtdv*dvdx;
+
+				*dx = dads*dsdx + dadt*dtdx;
+			}
+			if(dy) {
+				float dudy = ccl_fetch(sd, du).dy;
+				float dvdy = ccl_fetch(sd, dv).dy;
+
+				float dsdy = dsdu*dudy + dsdv*dvdy;
+				float dtdy = dtdu*dudy + dtdv*dvdy;
+
+				*dy = dads*dsdy + dadt*dtdy;
+			}
+		}
+#endif
+
+		return a;
+	}
+	else 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);
 
@@ -186,9 +275,8 @@ ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const Shader
 	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;
+		uint4 v = subd_triangle_patch_indices(kg, patch);
 
 		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));
@@ -200,9 +288,9 @@ ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const Shader
 			f3 = (f3+f0)*0.5f;
 		}
 
-		a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
-		b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
-		c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
+		float3 a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
+		float3 b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
+		float3 c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*a + ccl_fetch(sd, dv).dx*b - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*c;
@@ -212,13 +300,12 @@ 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(desc.element == ATTR_ELEMENT_CORNER || desc.element == ATTR_ELEMENT_CORNER_BYTE) {
-		int corners[4];
-		subd_triangle_patch_corners(kg, patch, corners);
-
 		float2 uv[3];
 		subd_triangle_patch_uv(kg, sd, uv);
 
-		float3 a, b, c;
+		int corners[4];
+		subd_triangle_patch_corners(kg, patch, corners);
+
 		float3 f0, f1, f2, f3;
 
 		if(desc.element == ATTR_ELEMENT_CORNER) {
@@ -239,9 +326,9 @@ ccl_device float3 subd_triangle_attribute_float3(KernelGlobals *kg, const Shader
 			f3 = (f3+f0)*0.5f;
 		}
 
-		a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
-		b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
-		c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
+		float3 a = mix(mix(f0, f1, uv[0].x), mix(f3, f2, uv[0].x), uv[0].y);
+		float3 b = mix(mix(f0, f1, uv[1].x), mix(f3, f2, uv[1].x), uv[1].y);
+		float3 c = mix(mix(f0, f1, uv[2].x), mix(f3, f2, uv[2].x), uv[2].y);
 
 #ifdef __RAY_DIFFERENTIALS__
 		if(dx) *dx = ccl_fetch(sd, du).dx*a + ccl_fetch(sd, dv).dx*b - (ccl_fetch(sd, du).dx + ccl_fetch(sd, dv).dx)*c;