forked from bartvdbraak/blender
Brecht Van Lommel
8fbd71e5f2
It turns out that the new Beckmann sampling function doesn't work well with Quasi Monte Carlo sampling, mainly near normal incidence where it can be worse than the previous sampler. In the new sampler the random number pattern gets split in two, warped and overlapped, which hurts the stratification, see the visualization in the differential revision. Now we use a precomputed table, which is much better behaved. GGX does not seem to benefit from using a precomputed table. Disadvantage is that this table adds 1MB of memory usage and 0.03s startup time to every render (on my quad core CPU). Differential Revision: https://developer.blender.org/D614
85 lines
3.4 KiB
C
85 lines
3.4 KiB
C
/*
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* Adapted from Open Shading Language with this license:
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*
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* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
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* All Rights Reserved.
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*
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* Modifications Copyright 2013, Blender Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Sony Pictures Imageworks nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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CCL_NAMESPACE_BEGIN
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/* Blackbody Node */
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ccl_device void svm_node_blackbody(KernelGlobals *kg, ShaderData *sd, float *stack, uint temperature_offset, uint col_offset)
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{
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/* Output */
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float3 color_rgb = make_float3(0.0f, 0.0f, 0.0f);
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/* Input */
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float temperature = stack_load_float(stack, temperature_offset);
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if (temperature < BB_DRAPPER) {
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/* just return very very dim red */
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color_rgb = make_float3(1.0e-6f,0.0f,0.0f);
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}
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else if (temperature <= BB_MAX_TABLE_RANGE) {
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/* This is the overall size of the table */
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const int lookuptablesize = 956;
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const float lookuptablenormalize = 1.0f/956.0f;
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/* reconstruct a proper index for the table lookup, compared to OSL we don't look up two colors
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just one (the OSL-lerp is also automatically done for us by "lookup_table_read") */
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float t = powf((temperature - BB_DRAPPER) * (1.0f / BB_TABLE_SPACING), (1.0f / BB_TABLE_XPOWER));
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int blackbody_table_offset = kernel_data.tables.blackbody_offset;
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/* Retrieve colors from the lookup table */
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float lutval = t*lookuptablenormalize;
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float R = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
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lutval = (t + 319.0f*1.0f)*lookuptablenormalize;
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float G = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
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lutval = (t + 319.0f*2.0f)*lookuptablenormalize;
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float B = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
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R = powf(R, BB_TABLE_YPOWER);
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G = powf(G, BB_TABLE_YPOWER);
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B = powf(B, BB_TABLE_YPOWER);
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color_rgb = make_float3(R, G, B);
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}
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/* Luminance */
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float l = linear_rgb_to_gray(color_rgb);
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if (l != 0.0f)
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color_rgb /= l;
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if (stack_valid(col_offset))
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stack_store_float3(stack, col_offset, color_rgb);
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}
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CCL_NAMESPACE_END
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