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Cycles / OSL:

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* Update the Oren Nayar shader to incorporate updates / fixes from r41968 and r44330.
This commit is contained in:
Thomas Dinges
2012-06-03 18:04:52 +00:00
parent e6d75d8974
commit f9856c1c2d
1 changed files with 10 additions and 47 deletions
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57
intern/cycles/kernel/osl/bsdf_oren_nayar.cpp
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@@ -16,31 +16,6 @@
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/*
* An implementation of Oren-Nayar reflectance model, public domain
* http://www1.cs.columbia.edu/CAVE/publications/pdfs/Oren_SIGGRAPH94.pdf
*
* NOTE:
* BSDF = A + B * cos() * sin() * tan()
*
* The parameter sigma means different from original.
* A and B are calculated by the following formula:
* 0 <= sigma <= 1
* A = 1 / ((1 + sigma / 2) * pi);
* B = sigma / ((1 + sigma / 2) * pi);
*
* This formula is derived as following:
*
* 0. Normalize A-term and B-term of BSDF *individually*.
* B-term is normalized at maximum point: dot(L, N) = 0.
* A = (1/pi) * A'
* B = (2/pi) * B'
*
* 1. Solve the following equation:
* A' + B' = 1
* B / A = sigma
*/
#include <OpenImageIO/fmath.h>
#include <OSL/genclosure.h>
#include "osl_closures.h"
@@ -60,8 +35,11 @@ public:
void setup() {
m_sigma = clamp(m_sigma, 0.0f, 1.0f);
m_a = 1.0f / ((1.0f + 0.5f * m_sigma) * M_PI);
m_b = m_sigma / ((1.0f + 0.5f * m_sigma) * M_PI);
float div = 1.0f / (M_PI + ((3.0f * M_PI - 4.0f) / 6.0f) * m_sigma);
m_a = 1.0f * div;
m_b = m_sigma * div;
}
bool mergeable(const ClosurePrimitive* other) const {
@@ -137,27 +115,12 @@ private:
float get_intensity(Vec3 const& n, Vec3 const& v, Vec3 const& l) const {
float nl = max(n.dot(l), 0.0f);
float nv = max(n.dot(v), 0.0f);
Vec3 al = l - nl * n;
al.normalize();
Vec3 av = v - nv * n;
av.normalize();
float t = max(al.dot(av), 0.0f);
float cos_a, cos_b;
if (nl < nv) {
cos_a = nl;
cos_b = nv;
float t = l.dot(v) - nl * nv;
if(t > 0.0f) {
t /= max(nl, vl) + 1e-8f;
}
else {
cos_a = nv;
cos_b = nl;
}
float sin_a = sqrtf(1.0f - cos_a * cos_a);
float tan_b = sqrtf(1.0f - cos_b * cos_b) / (cos_b + FLT_MIN);
return nl * (m_a + m_b * t * sin_a * tan_b);
return nl * (m_a + m_b * t);
}
};