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 * Remove specific license info from outdated readme.txt, instead leave details to the source files.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
39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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*
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* Adapted from Open Shading Language
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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 2011-2022 Blender Foundation. */
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float fresnel_dielectric_cos(float cosi, float eta)
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{
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/* compute fresnel reflectance without explicitly computing
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* the refracted direction */
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float c = fabs(cosi);
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float g = eta * eta - 1 + c * c;
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float result;
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if (g > 0) {
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g = sqrt(g);
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float A = (g - c) / (g + c);
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float B = (c * (g + c) - 1) / (c * (g - c) + 1);
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result = 0.5 * A * A * (1 + B * B);
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}
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else
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result = 1.0; /* TIR (no refracted component) */
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return result;
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}
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color fresnel_conductor(float cosi, color eta, color k)
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{
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color cosi2 = color(cosi * cosi);
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color one = color(1, 1, 1);
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color tmp_f = eta * eta + k * k;
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color tmp = tmp_f * cosi2;
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color Rparl2 = (tmp - (2.0 * eta * cosi) + one) / (tmp + (2.0 * eta * cosi) + one);
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color Rperp2 = (tmp_f - (2.0 * eta * cosi) + cosi2) / (tmp_f + (2.0 * eta * cosi) + cosi2);
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return (Rparl2 + Rperp2) * 0.5;
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}
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