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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "stdosl.h"
/* "Bump Mapping Unparameterized Surfaces on the GPU"
* Morten S. Mikkelsen, 2010 */
surface node_bump(
int invert = 0,
normal NormalIn = N,
float Strength = 0.1,
float Distance = 1.0,
float SampleCenter = 0.0,
float SampleX = 0.0,
float SampleY = 0.0,
output normal NormalOut = 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;
float absdet = fabs(det);
float strength = max(Strength, 0.0);
float dist = Distance;
if (invert)
dist *= -1.0;
/* compute and output perturbed normal */
NormalOut = normalize(absdet * NormalIn - dist * sign(det) * surfgrad);
NormalOut = normalize(strength * NormalOut + (1.0 - strength) * NormalIn);
}
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