Cycles: CUDA bicubic and tricubic texture interpolation support.

While cubic interpolation is quite expensive on the CPU compared to linear
interpolation, the difference on the GPU is quite small.

1 files changed, 143 insertions, 8 deletions

diff --git a/intern/cycles/kernel/kernels/cuda/kernel_cuda_image.h b/intern/cycles/kernel/kernels/cuda/kernel_cuda_image.h
index 00f6954003d..269e74f6164 100644
--- a/intern/cycles/kernel/kernels/cuda/kernel_cuda_image.h
+++ b/intern/cycles/kernel/kernels/cuda/kernel_cuda_image.h
@@ -18,7 +18,115 @@
 
 /* Kepler */
 
-ccl_device float4 kernel_tex_image_interp(void *kg, int id, float x, float y)
+/* w0, w1, w2, and w3 are the four cubic B-spline basis functions. */
+ccl_device float cubic_w0(float a)
+{
+	return (1.0f/6.0f)*(a*(a*(-a + 3.0f) - 3.0f) + 1.0f);
+}
+
+ccl_device float cubic_w1(float a)
+{
+	return (1.0f/6.0f)*(a*a*(3.0f*a - 6.0f) + 4.0f);
+}
+
+ccl_device float cubic_w2(float a)
+{
+	return (1.0f/6.0f)*(a*(a*(-3.0f*a + 3.0f) + 3.0f) + 1.0f);
+}
+
+ccl_device float cubic_w3(float a)
+{
+	return (1.0f/6.0f)*(a*a*a);
+}
+
+/* g0 and g1 are the two amplitude functions. */
+ccl_device float cubic_g0(float a)
+{
+	return cubic_w0(a) + cubic_w1(a);
+}
+
+ccl_device float cubic_g1(float a)
+{
+	return cubic_w2(a) + cubic_w3(a);
+}
+
+/* h0 and h1 are the two offset functions */
+ccl_device float cubic_h0(float a)
+{
+	/* Note +0.5 offset to compensate for CUDA linear filtering convention. */
+	return -1.0f + cubic_w1(a) / (cubic_w0(a) + cubic_w1(a)) + 0.5f;
+}
+
+ccl_device float cubic_h1(float a)
+{
+	return 1.0f + cubic_w3(a) / (cubic_w2(a) + cubic_w3(a)) + 0.5f;
+}
+
+/* Fast bicubic texture lookup using 4 bilinear lookups, adapted from CUDA samples. */
+template<typename T>
+ccl_device T kernel_tex_image_interp_bicubic(const TextureInfo& info, CUtexObject tex, float x, float y)
+{
+	x = (x * info.width) - 0.5f;
+	y = (y * info.height) - 0.5f;
+
+	float px = floor(x);
+	float py = floor(y);
+	float fx = x - px;
+	float fy = y - py;
+
+	float g0x = cubic_g0(fx);
+	float g1x = cubic_g1(fx);
+	float x0 = (px + cubic_h0(fx)) / info.width;
+	float x1 = (px + cubic_h1(fx)) / info.width;
+	float y0 = (py + cubic_h0(fy)) / info.height;
+	float y1 = (py + cubic_h1(fy)) / info.height;
+
+	return cubic_g0(fy) * (g0x * tex2D<T>(tex, x0, y0) +
+	                       g1x * tex2D<T>(tex, x1, y0)) +
+	       cubic_g1(fy) * (g0x * tex2D<T>(tex, x0, y1) +
+	                       g1x * tex2D<T>(tex, x1, y1));
+}
+
+/* Fast tricubic texture lookup using 8 bilinear lookups. */
+template<typename T>
+ccl_device T kernel_tex_image_interp_bicubic_3d(const TextureInfo& info, CUtexObject tex, float x, float y, float z)
+{
+	x = (x * info.width) - 0.5f;
+	y = (y * info.height) - 0.5f;
+	z = (z * info.depth) - 0.5f;
+
+	float px = floor(x);
+	float py = floor(y);
+	float pz = floor(z);
+	float fx = x - px;
+	float fy = y - py;
+	float fz = z - pz;
+
+	float g0x = cubic_g0(fx);
+	float g1x = cubic_g1(fx);
+	float g0y = cubic_g0(fy);
+	float g1y = cubic_g1(fy);
+	float g0z = cubic_g0(fz);
+	float g1z = cubic_g1(fz);
+
+	float x0 = (px + cubic_h0(fx)) / info.width;
+	float x1 = (px + cubic_h1(fx)) / info.width;
+	float y0 = (py + cubic_h0(fy)) / info.height;
+	float y1 = (py + cubic_h1(fy)) / info.height;
+	float z0 = (pz + cubic_h0(fz)) / info.depth;
+	float z1 = (pz + cubic_h1(fz)) / info.depth;
+
+	return g0z * (g0y * (g0x * tex3D<T>(tex, x0, y0, z0) +
+	                     g1x * tex3D<T>(tex, x1, y0, z0)) +
+	              g1y * (g0x * tex3D<T>(tex, x0, y1, z0) +
+	                     g1x * tex3D<T>(tex, x1, y1, z0))) +
+	       g1z * (g0y * (g0x * tex3D<T>(tex, x0, y0, z1) +
+	                     g1x * tex3D<T>(tex, x1, y0, z1)) +
+	              g1y * (g0x * tex3D<T>(tex, x0, y1, z1) +
+	                     g1x * tex3D<T>(tex, x1, y1, z1)));
+}
+
+ccl_device float4 kernel_tex_image_interp(KernelGlobals *kg, int id, float x, float y)
 {
 	const TextureInfo& info = kernel_tex_fetch(__texture_info, id);
 	CUtexObject tex = (CUtexObject)info.data;
@@ -29,29 +137,56 @@ ccl_device float4 kernel_tex_image_interp(void *kg, int id, float x, float y)
 	   texture_type == IMAGE_DATA_TYPE_BYTE4 ||
 	   texture_type == IMAGE_DATA_TYPE_HALF4)
 	{
-		return tex2D<float4>(tex, x, y);
+		if(info.interpolation == INTERPOLATION_CUBIC) {
+			return kernel_tex_image_interp_bicubic<float4>(info, tex, x, y);
+		}
+		else {
+			return tex2D<float4>(tex, x, y);
+		}
 	}
 	/* float, byte and half */
 	else {
-		float f = tex2D<float>(tex, x, y);
+		float f;
+
+		if(info.interpolation == INTERPOLATION_CUBIC) {
+			f = kernel_tex_image_interp_bicubic<float>(info, tex, x, y);
+		}
+		else {
+			f = tex2D<float>(tex, x, y);
+		}
+
 		return make_float4(f, f, f, 1.0f);
 	}
 }
 
-ccl_device float4 kernel_tex_image_interp_3d(void *kg, int id, float x, float y, float z)
+ccl_device float4 kernel_tex_image_interp_3d(KernelGlobals *kg, int id, float x, float y, float z, InterpolationType interp)
 {
 	const TextureInfo& info = kernel_tex_fetch(__texture_info, id);
 	CUtexObject tex = (CUtexObject)info.data;
+	uint interpolation = (interp == INTERPOLATION_NONE)? info.interpolation: interp;
 
 	const int texture_type = kernel_tex_type(id);
 	if(texture_type == IMAGE_DATA_TYPE_FLOAT4 ||
 	   texture_type == IMAGE_DATA_TYPE_BYTE4 ||
 	   texture_type == IMAGE_DATA_TYPE_HALF4)
 	{
-		return tex3D<float4>(tex, x, y, z);
+		if(interpolation == INTERPOLATION_CUBIC) {
+			return kernel_tex_image_interp_bicubic_3d<float4>(info, tex, x, y, z);
+		}
+		else {
+			return tex3D<float4>(tex, x, y, z);
+		}
 	}
 	else {
-		float f = tex3D<float>(tex, x, y, z);
+		float f;
+
+		if(interpolation == INTERPOLATION_CUBIC) {
+			f = kernel_tex_image_interp_bicubic_3d<float>(info, tex, x, y, z);
+		}
+		else {
+			f = tex3D<float>(tex, x, y, z);
+		}
+
 		return make_float4(f, f, f, 1.0f);
 	}
 }
@@ -60,7 +195,7 @@ ccl_device float4 kernel_tex_image_interp_3d(void *kg, int id, float x, float y,
 
 /* Fermi */
 
-ccl_device float4 kernel_tex_image_interp(void *kg, int id, float x, float y)
+ccl_device float4 kernel_tex_image_interp(KernelGlobals *kg, int id, float x, float y)
 {
 	float4 r;
 	switch(id) {
@@ -158,7 +293,7 @@ ccl_device float4 kernel_tex_image_interp(void *kg, int id, float x, float y)
 	return r;
 }
 
-ccl_device float4 kernel_tex_image_interp_3d(void *kg, int id, float x, float y, float z)
+ccl_device float4 kernel_tex_image_interp_3d(KernelGlobals *kg, int id, float x, float y, float z)
 {
 	float4 r;
 	switch(id) {