forked from bartvdbraak/blender
190 lines
6.4 KiB
C
190 lines
6.4 KiB
C
/*
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* Adapted from Open Shading Language with this license:
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*
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* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
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* All Rights Reserved.
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*
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* Modifications Copyright 2011, Blender Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Sony Pictures Imageworks nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BSDF_WARD_H__
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#define __BSDF_WARD_H__
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CCL_NAMESPACE_BEGIN
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/* WARD */
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__device int bsdf_ward_setup(ShaderClosure *sc)
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{
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sc->data0 = clamp(sc->data0, 1e-4f, 1.0f); /* m_ax */
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sc->data1 = clamp(sc->data1, 1e-4f, 1.0f); /* m_ay */
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sc->type = CLOSURE_BSDF_WARD_ID;
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return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
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}
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__device void bsdf_ward_blur(ShaderClosure *sc, float roughness)
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{
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sc->data0 = fmaxf(roughness, sc->data0); /* m_ax */
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sc->data1 = fmaxf(roughness, sc->data1); /* m_ay */
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}
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__device float3 bsdf_ward_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
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{
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float m_ax = sc->data0;
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float m_ay = sc->data1;
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float3 N = sc->N;
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float3 T = sc->T;
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float cosNO = dot(N, I);
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float cosNI = dot(N, omega_in);
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if(cosNI > 0.0f && cosNO > 0.0f) {
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cosNO = max(cosNO, 1e-4f);
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cosNI = max(cosNI, 1e-4f);
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// get half vector and get x,y basis on the surface for anisotropy
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float3 H = normalize(omega_in + I); // normalize needed for pdf
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float3 X, Y;
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make_orthonormals_tangent(N, T, &X, &Y);
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// eq. 4
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float dotx = dot(H, X) / m_ax;
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float doty = dot(H, Y) / m_ay;
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float dotn = dot(H, N);
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float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
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float denom = (M_4PI_F * m_ax * m_ay * sqrtf(cosNO * cosNI));
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float exp_val = expf(-exp_arg);
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float out = cosNI * exp_val / denom;
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float oh = dot(H, I);
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denom = M_4PI_F * m_ax * m_ay * oh * dotn * dotn * dotn;
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*pdf = exp_val / denom;
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return make_float3 (out, out, out);
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}
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return make_float3 (0, 0, 0);
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}
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__device float3 bsdf_ward_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
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{
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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__device int bsdf_ward_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
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{
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float m_ax = sc->data0;
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float m_ay = sc->data1;
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float3 N = sc->N;
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float3 T = sc->T;
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float cosNO = dot(N, I);
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if(cosNO > 0.0f) {
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// get x,y basis on the surface for anisotropy
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float3 X, Y;
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make_orthonormals_tangent(N, T, &X, &Y);
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// generate random angles for the half vector
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// eq. 7 (taking care around discontinuities to keep
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//ttoutput angle in the right quadrant)
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// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
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//tttt and sin(atan(x)) == x/sqrt(1+x^2)
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float alphaRatio = m_ay / m_ax;
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float cosPhi, sinPhi;
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if(randu < 0.25f) {
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float val = 4 * randu;
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float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
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cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = tanPhi * cosPhi;
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}
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else if(randu < 0.5f) {
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float val = 1 - 4 * (0.5f - randu);
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float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
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// phi = M_PI_F - phi;
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cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = -tanPhi * cosPhi;
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}
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else if(randu < 0.75f) {
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float val = 4 * (randu - 0.5f);
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float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
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//phi = M_PI_F + phi;
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cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = tanPhi * cosPhi;
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}
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else {
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float val = 1 - 4 * (1 - randu);
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float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
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// phi = M_2PI_F - phi;
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cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = -tanPhi * cosPhi;
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}
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// eq. 6
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// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
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//tttt and sin(atan(x)) == x/sqrt(1+x^2)
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float thetaDenom = (cosPhi * cosPhi) / (m_ax * m_ax) + (sinPhi * sinPhi) / (m_ay * m_ay);
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float tanTheta2 = -logf(1 - randv) / thetaDenom;
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float cosTheta = 1 / sqrtf(1 + tanTheta2);
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float sinTheta = cosTheta * sqrtf(tanTheta2);
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float3 h; // already normalized becaused expressed from spherical coordinates
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h.x = sinTheta * cosPhi;
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h.y = sinTheta * sinPhi;
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h.z = cosTheta;
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// compute terms that are easier in local space
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float dotx = h.x / m_ax;
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float doty = h.y / m_ay;
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float dotn = h.z;
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// transform to world space
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h = h.x * X + h.y * Y + h.z * N;
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// generate the final sample
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float oh = dot(h, I);
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*omega_in = 2.0f * oh * h - I;
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if(dot(Ng, *omega_in) > 0) {
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float cosNI = dot(N, *omega_in);
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if(cosNI > 0) {
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cosNO = max(cosNO, 1e-4f);
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cosNI = max(cosNI, 1e-4f);
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// eq. 9
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float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
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float denom = M_4PI_F * m_ax * m_ay * oh * dotn * dotn * dotn;
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*pdf = expf(-exp_arg) / denom;
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// compiler will reuse expressions already computed
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denom = (M_4PI_F * m_ax * m_ay * sqrtf(cosNO * cosNI));
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float power = cosNI * expf(-exp_arg) / denom;
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*eval = make_float3(power, power, power);
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#ifdef __RAY_DIFFERENTIALS__
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*domega_in_dx = (2 * dot(N, dIdx)) * N - dIdx;
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*domega_in_dy = (2 * dot(N, dIdy)) * N - dIdy;
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#endif
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}
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}
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}
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return LABEL_REFLECT|LABEL_GLOSSY;
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}
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CCL_NAMESPACE_END
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#endif /* __BSDF_WARD_H__ */
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