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/* SPDX-License-Identifier: BSD-3-Clause
*
* Adapted from Open Shading Language
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011-2022 Blender Foundation. */
#pragma once
CCL_NAMESPACE_BEGIN
/* Wavelength to RGB */
ccl_device_noinline void svm_node_wavelength(KernelGlobals kg,
ccl_private ShaderData *sd,
ccl_private float *stack,
uint wavelength,
uint color_out)
{
float lambda_nm = stack_load_float(stack, wavelength);
float ii = (lambda_nm - 380.0f) * (1.0f / 5.0f); // scaled 0..80
int i = float_to_int(ii);
float3 color;
if (i < 0 || i >= 80) {
color = make_float3(0.0f, 0.0f, 0.0f);
}
else {
ii -= i;
ccl_constant float *c = cie_colour_match[i];
color = interp(make_float3(c[0], c[1], c[2]), make_float3(c[3], c[4], c[5]), ii);
}
color = xyz_to_rgb(kg, color);
color *= 1.0f / 2.52f; // Empirical scale from lg to make all comps <= 1
/* Clamp to zero if values are smaller */
color = max(color, make_float3(0.0f, 0.0f, 0.0f));
stack_store_float3(stack, color_out, color);
}
CCL_NAMESPACE_END
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