9cfc7967dd
* Replace license text in headers with SPDX identifiers. * Remove specific license info from outdated readme.txt, instead leave details to the source files. * Add list of SPDX license identifiers used, and corresponding license texts. * Update copyright dates while we're at it. Ref D14069, T95597
110 lines
4.3 KiB
C
110 lines
4.3 KiB
C
/* SPDX-License-Identifier: Apache-2.0
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* Copyright 2011-2022 Blender Foundation */
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#pragma once
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CCL_NAMESPACE_BEGIN
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/* IES Light */
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ccl_device_inline float interpolate_ies_vertical(
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KernelGlobals kg, int ofs, int v, int v_num, float v_frac, int h)
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{
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/* Since lookups are performed in spherical coordinates, clamping the coordinates at the low end
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* of v (corresponding to the north pole) would result in artifacts. The proper way of dealing
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* with this would be to lookup the corresponding value on the other side of the pole, but since
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* the horizontal coordinates might be nonuniform, this would require yet another interpolation.
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* Therefore, the assumption is made that the light is going to be symmetrical, which means that
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* we can just take the corresponding value at the current horizontal coordinate. */
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#define IES_LOOKUP(v) kernel_tex_fetch(__ies, ofs + h * v_num + (v))
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/* If v is zero, assume symmetry and read at v=1 instead of v=-1. */
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float a = IES_LOOKUP((v == 0) ? 1 : v - 1);
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float b = IES_LOOKUP(v);
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float c = IES_LOOKUP(v + 1);
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float d = IES_LOOKUP(min(v + 2, v_num - 1));
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#undef IES_LOOKUP
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return cubic_interp(a, b, c, d, v_frac);
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}
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ccl_device_inline float kernel_ies_interp(KernelGlobals kg, int slot, float h_angle, float v_angle)
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{
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/* Find offset of the IES data in the table. */
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int ofs = __float_as_int(kernel_tex_fetch(__ies, slot));
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if (ofs == -1) {
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return 100.0f;
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}
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int h_num = __float_as_int(kernel_tex_fetch(__ies, ofs++));
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int v_num = __float_as_int(kernel_tex_fetch(__ies, ofs++));
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#define IES_LOOKUP_ANGLE_H(h) kernel_tex_fetch(__ies, ofs + (h))
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#define IES_LOOKUP_ANGLE_V(v) kernel_tex_fetch(__ies, ofs + h_num + (v))
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/* Check whether the angle is within the bounds of the IES texture. */
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if (v_angle >= IES_LOOKUP_ANGLE_V(v_num - 1)) {
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return 0.0f;
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}
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kernel_assert(v_angle >= IES_LOOKUP_ANGLE_V(0));
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kernel_assert(h_angle >= IES_LOOKUP_ANGLE_H(0));
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kernel_assert(h_angle <= IES_LOOKUP_ANGLE_H(h_num - 1));
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/* Lookup the angles to find the table position. */
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int h_i, v_i;
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/* TODO(lukas): Consider using bisection.
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* Probably not worth it for the vast majority of IES files. */
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for (h_i = 0; IES_LOOKUP_ANGLE_H(h_i + 1) < h_angle; h_i++)
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;
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for (v_i = 0; IES_LOOKUP_ANGLE_V(v_i + 1) < v_angle; v_i++)
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;
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float h_frac = inverse_lerp(IES_LOOKUP_ANGLE_H(h_i), IES_LOOKUP_ANGLE_H(h_i + 1), h_angle);
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float v_frac = inverse_lerp(IES_LOOKUP_ANGLE_V(v_i), IES_LOOKUP_ANGLE_V(v_i + 1), v_angle);
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#undef IES_LOOKUP_ANGLE_H
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#undef IES_LOOKUP_ANGLE_V
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/* Skip forward to the actual intensity data. */
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ofs += h_num + v_num;
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/* Perform cubic interpolation along the horizontal coordinate to get the intensity value.
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* If h_i is zero, just wrap around since the horizontal angles always go over the full circle.
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* However, the last entry (360°) equals the first one, so we need to wrap around to the one
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* before that. */
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float a = interpolate_ies_vertical(
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kg, ofs, v_i, v_num, v_frac, (h_i == 0) ? h_num - 2 : h_i - 1);
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float b = interpolate_ies_vertical(kg, ofs, v_i, v_num, v_frac, h_i);
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float c = interpolate_ies_vertical(kg, ofs, v_i, v_num, v_frac, h_i + 1);
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/* Same logic here, wrap around to the second element if necessary. */
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float d = interpolate_ies_vertical(
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kg, ofs, v_i, v_num, v_frac, (h_i + 2 == h_num) ? 1 : h_i + 2);
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/* Cubic interpolation can result in negative values, so get rid of them. */
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return max(cubic_interp(a, b, c, d, h_frac), 0.0f);
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}
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ccl_device_noinline void svm_node_ies(KernelGlobals kg,
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ccl_private ShaderData *sd,
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ccl_private float *stack,
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uint4 node)
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{
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uint vector_offset, strength_offset, fac_offset, slot = node.z;
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svm_unpack_node_uchar3(node.y, &strength_offset, &vector_offset, &fac_offset);
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float3 vector = stack_load_float3(stack, vector_offset);
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float strength = stack_load_float_default(stack, strength_offset, node.w);
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vector = normalize(vector);
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float v_angle = safe_acosf(-vector.z);
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float h_angle = atan2f(vector.x, vector.y) + M_PI_F;
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float fac = strength * kernel_ies_interp(kg, slot, h_angle, v_angle);
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if (stack_valid(fac_offset)) {
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stack_store_float(stack, fac_offset, fac);
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}
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}
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CCL_NAMESPACE_END
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