2012-06-06 16:00:21 +00:00
|
|
|
/*
|
2019-01-28 10:51:24 +00:00
|
|
|
* Adapted from Open Shading Language with this license:
|
2012-06-06 16:00:21 +00:00
|
|
|
*
|
2019-01-28 10:51:24 +00:00
|
|
|
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
|
|
|
|
* All Rights Reserved.
|
2012-06-06 16:00:21 +00:00
|
|
|
*
|
2019-01-28 10:51:24 +00:00
|
|
|
* Modifications Copyright 2011, Blender Foundation.
|
2013-08-18 14:16:15 +00:00
|
|
|
*
|
2019-01-28 10:51:24 +00:00
|
|
|
* 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.
|
2012-06-06 16:00:21 +00:00
|
|
|
*/
|
2018-07-06 08:17:58 +00:00
|
|
|
|
2013-05-26 17:10:22 +00:00
|
|
|
float fresnel_dielectric_cos(float cosi, float eta)
|
2011-04-27 11:58:34 +00:00
|
|
|
{
|
|
|
|
/* compute fresnel reflectance without explicitly computing
|
2012-06-09 17:22:52 +00:00
|
|
|
* the refracted direction */
|
2013-05-26 17:10:22 +00:00
|
|
|
float c = fabs(cosi);
|
2011-04-27 11:58:34 +00:00
|
|
|
float g = eta * eta - 1 + c * c;
|
|
|
|
float result;
|
|
|
|
|
2012-06-04 22:44:58 +00:00
|
|
|
if (g > 0) {
|
2011-04-27 11:58:34 +00:00
|
|
|
g = sqrt(g);
|
2012-06-04 22:44:58 +00:00
|
|
|
float A = (g - c) / (g + c);
|
|
|
|
float B = (c * (g + c) - 1) / (c * (g - c) + 1);
|
|
|
|
result = 0.5 * A * A * (1 + B * B);
|
2011-04-27 11:58:34 +00:00
|
|
|
}
|
|
|
|
else
|
|
|
|
result = 1.0; /* TIR (no refracted component) */
|
|
|
|
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
2014-09-07 16:28:59 +00:00
|
|
|
color fresnel_conductor(float cosi, color eta, color k)
|
|
|
|
{
|
2014-09-29 16:04:34 +00:00
|
|
|
color cosi2 = color(cosi * cosi);
|
2014-09-07 16:28:59 +00:00
|
|
|
color one = color(1, 1, 1);
|
|
|
|
color tmp_f = eta * eta + k * k;
|
|
|
|
color tmp = tmp_f * cosi2;
|
|
|
|
color Rparl2 = (tmp - (2.0 * eta * cosi) + one) / (tmp + (2.0 * eta * cosi) + one);
|
|
|
|
color Rperp2 = (tmp_f - (2.0 * eta * cosi) + cosi2) / (tmp_f + (2.0 * eta * cosi) + cosi2);
|
|
|
|
return (Rparl2 + Rperp2) * 0.5;
|
|
|
|
}
|