forked from bartvdbraak/blender
2efe0f6733
* Rename fresnel_dielectric() to fresnel_dielectric_cos() to match SVM, easier when searching code. * Also remove an old code comment in bsdf_reflection.h from Cycles branch days.
37 lines
1.1 KiB
C
37 lines
1.1 KiB
C
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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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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