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/*
* Adapted from Open Shading Language with this license:
*
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2013, Blender Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Sony Pictures Imageworks nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
CCL_NAMESPACE_BEGIN
/* Blackbody Node */
ccl_device void svm_node_blackbody(KernelGlobals *kg, ShaderData *sd, float *stack, uint temperature_offset, uint col_offset)
{
/* Output */
float3 color_rgb = make_float3(0.0f, 0.0f, 0.0f);
/* Input */
float temperature = stack_load_float(stack, temperature_offset);
if (temperature < BB_DRAPER) {
/* just return very very dim red */
color_rgb = make_float3(1.0e-6f,0.0f,0.0f);
}
else if (temperature <= BB_MAX_TABLE_RANGE) {
/* This is the overall size of the table */
const int lookuptablesize = 956;
const float lookuptablenormalize = 1.0f/956.0f;
/* reconstruct a proper index for the table lookup, compared to OSL we don't look up two colors
just one (the OSL-lerp is also automatically done for us by "lookup_table_read") */
float t = powf((temperature - BB_DRAPER) * (1.0f / BB_TABLE_SPACING), (1.0f / BB_TABLE_XPOWER));
int blackbody_table_offset = kernel_data.tables.blackbody_offset;
/* Retrieve colors from the lookup table */
float lutval = t*lookuptablenormalize;
float R = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
lutval = (t + 319.0f*1.0f)*lookuptablenormalize;
float G = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
lutval = (t + 319.0f*2.0f)*lookuptablenormalize;
float B = lookup_table_read(kg, lutval, blackbody_table_offset, lookuptablesize);
R = powf(R, BB_TABLE_YPOWER);
G = powf(G, BB_TABLE_YPOWER);
B = powf(B, BB_TABLE_YPOWER);
color_rgb = make_float3(R, G, B);
}
/* Luminance */
float l = linear_rgb_to_gray(color_rgb);
if (l != 0.0f)
color_rgb /= l;
if (stack_valid(col_offset))
stack_store_float3(stack, col_offset, color_rgb);
}
CCL_NAMESPACE_END
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