diff options
| -rw-r--r-- | intern/cycles/kernel/osl/bsdf_oren_nayar.cpp | 57 |
1 files changed, 10 insertions, 47 deletions
diff --git a/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp b/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp index a42c81e78f3..5d2ca909f93 100644 --- a/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp +++ b/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp @@ -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); } }; |