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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "stdosl.h"
/* "Bump Mapping Unparameterized Surfaces on the GPU"
* Morten S. Mikkelsen, 2010 */
surface node_bump(
normal NormalIn = N,
float Strength = 0.0,
float SampleCenter = 0.0,
float SampleX = 0.0,
float SampleY = 0.0,
output normal Normal = N)
{
/* get surface tangents from normal */
vector dPdx = Dx(P);
vector dPdy = Dy(P);
vector Rx = cross(dPdy, NormalIn);
vector Ry = cross(NormalIn, dPdx);
/* compute surface gradient and determinant */
float det = dot(dPdx, Rx);
vector surfgrad = (SampleX - SampleCenter) * Rx + (SampleY - SampleCenter) * Ry;
surfgrad *= Strength;
float absdet = fabs(det);
/* compute and output perturbed normal */
Normal = normalize(absdet * NormalIn - sign(det) * surfgrad);
}
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