diff options
Diffstat (limited to 'intern/cycles/kernel/osl/bsdf_oren_nayar.cpp')
| -rw-r--r-- | intern/cycles/kernel/osl/bsdf_oren_nayar.cpp | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp b/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp new file mode 100644 index 00000000000..a42c81e78f3 --- /dev/null +++ b/intern/cycles/kernel/osl/bsdf_oren_nayar.cpp @@ -0,0 +1,174 @@ +/* + * 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. + */ + +/* + * 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" + +CCL_NAMESPACE_BEGIN + +using namespace OSL; + + +class OrenNayarClosure: public BSDFClosure { +public: + Vec3 m_N; + float m_sigma; + float m_a, m_b; + + OrenNayarClosure(): BSDFClosure(Labels::DIFFUSE) {} + + 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); + } + + bool mergeable(const ClosurePrimitive* other) const { + const OrenNayarClosure* comp = static_cast<const OrenNayarClosure*>(other); + return + m_N == comp->m_N && + m_sigma == comp->m_sigma && + BSDFClosure::mergeable(other); + } + + size_t memsize() const { + return sizeof(*this); + } + + const char* name() const { + return "oren_nayar"; + } + + void print_on(std::ostream& out) const { + out << name() << " ("; + out << "(" << m_N[0] << ", " << m_N[1] << ", " << m_N[2] << "), "; + out << m_sigma; + out << ")"; + } + + float albedo(const Vec3& omega_out) const { + return 1.0f; + } + + Color3 eval_reflect(const Vec3& omega_out, const Vec3& omega_in, float& pdf) const { + if (m_N.dot(omega_in) > 0.0f) { + pdf = float(0.5 * M_1_PI); + float is = get_intensity(m_N, omega_out, omega_in); + return Color3(is, is, is); + } + else { + pdf = 0.0f; + return Color3(0.0f, 0.0f, 0.0f); + } + } + + Color3 eval_transmit(const Vec3& omega_out, const Vec3& omega_in, float& pdf) const { + return Color3(0.0f, 0.0f, 0.0f); + } + + ustring sample( + const Vec3& Ng, + const Vec3& omega_out, const Vec3& domega_out_dx, const Vec3& domega_out_dy, + float randu, float randv, + Vec3& omega_in, Vec3& domega_in_dx, Vec3& domega_in_dy, + float& pdf, Color3& eval + ) const { + sample_uniform_hemisphere (m_N, omega_out, randu, randv, omega_in, pdf); + + if (Ng.dot(omega_in) > 0.0f) { + float is = get_intensity(m_N, omega_out, omega_in); + eval.setValue(is, is, is); + + // TODO: find a better approximation for the bounce + domega_in_dx = (2.0f * m_N.dot(domega_out_dx)) * m_N - domega_out_dx; + domega_in_dy = (2.0f * m_N.dot(domega_out_dy)) * m_N - domega_out_dy; + domega_in_dx *= 125.0f; + domega_in_dy *= 125.0f; + } + else { + pdf = 0.0f; + } + + return Labels::REFLECT; + } + +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; + } + 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); + } +}; + +ClosureParam bsdf_oren_nayar_params[] = { + CLOSURE_VECTOR_PARAM (OrenNayarClosure, m_N), + CLOSURE_FLOAT_PARAM (OrenNayarClosure, m_sigma), + CLOSURE_STRING_KEYPARAM ("label"), + CLOSURE_FINISH_PARAM (OrenNayarClosure) +}; + +CLOSURE_PREPARE(bsdf_oren_nayar_prepare, OrenNayarClosure) + + +CCL_NAMESPACE_END |