[Bf-blender-cvs] [23c2768] master: Cycles: Add multi-scattering, energy-conserving GGX as an option to the Glossy, Anisotropic and Glass BSDFs
Lukas Stockner
noreply at git.blender.org
Thu Jun 23 23:43:07 CEST 2016
Commit: 23c276832b1bb43712756c0ea3af954557ab05e7
Author: Lukas Stockner
Date: Thu Jun 23 22:56:43 2016 +0200
Branches: master
https://developer.blender.org/rB23c276832b1bb43712756c0ea3af954557ab05e7
Cycles: Add multi-scattering, energy-conserving GGX as an option to the Glossy, Anisotropic and Glass BSDFs
This commit adds a new distribution to the Glossy, Anisotropic and Glass BSDFs that implements the
multiple-scattering microfacet model described in the paper "Multiple-Scattering Microfacet BSDFs with the Smith Model".
Essentially, the improvement is that unlike classical GGX, which only models single scattering and assumes
the contribution of multiple bounces to be zero, this new model performs a random walk on the microsurface until
the ray leaves it again, which ensures perfect energy conservation.
In practise, this means that the "darkening problem" - GGX materials becoming darker with increasing
roughness - is solved in a physically correct and efficient way.
The downside of this model is that it has no (known) analytic expression for evalation. However, it can be
evaluated stochastically, and although the correct PDF isn't known either, the properties of MIS and the
balance heuristic guarantee an unbiased result at the cost of slightly higher noise.
Reviewers: dingto, #cycles, brecht
Reviewed By: dingto, #cycles, brecht
Subscribers: bliblubli, ace_dragon, gregzaal, brecht, harvester, dingto, marcog, swerner, jtheninja, Blendify, nutel
Differential Revision: https://developer.blender.org/D2002
===================================================================
M intern/cycles/blender/blender_shader.cpp
M intern/cycles/kernel/CMakeLists.txt
M intern/cycles/kernel/closure/bsdf.h
A intern/cycles/kernel/closure/bsdf_microfacet_multi.h
A intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h
M intern/cycles/kernel/closure/bsdf_util.h
M intern/cycles/kernel/kernel_bake.h
M intern/cycles/kernel/kernel_emission.h
M intern/cycles/kernel/kernel_path.h
M intern/cycles/kernel/kernel_path_branched.h
M intern/cycles/kernel/kernel_shader.h
M intern/cycles/kernel/kernel_shadow.h
M intern/cycles/kernel/kernel_subsurface.h
M intern/cycles/kernel/kernel_types.h
M intern/cycles/kernel/osl/osl_closures.cpp
M intern/cycles/kernel/osl/osl_closures.h
M intern/cycles/kernel/osl/osl_shader.cpp
M intern/cycles/kernel/shaders/node_anisotropic_bsdf.osl
M intern/cycles/kernel/shaders/node_glass_bsdf.osl
M intern/cycles/kernel/shaders/node_glossy_bsdf.osl
M intern/cycles/kernel/shaders/stdosl.h
M intern/cycles/kernel/split/kernel_shader_eval.h
M intern/cycles/kernel/svm/svm_closure.h
M intern/cycles/kernel/svm/svm_types.h
M intern/cycles/render/nodes.cpp
M intern/cycles/util/util_math.h
M source/blender/makesdna/DNA_node_types.h
M source/blender/makesrna/intern/rna_nodetree.c
M source/blender/nodes/NOD_static_types.h
===================================================================
diff --git a/intern/cycles/blender/blender_shader.cpp b/intern/cycles/blender/blender_shader.cpp
index 78a28b7..7ca23f2 100644
--- a/intern/cycles/blender/blender_shader.cpp
+++ b/intern/cycles/blender/blender_shader.cpp
@@ -393,6 +393,9 @@ static ShaderNode *add_node(Scene *scene,
case BL::ShaderNodeBsdfAnisotropic::distribution_GGX:
aniso->distribution = CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID;
break;
+ case BL::ShaderNodeBsdfAnisotropic::distribution_MULTI_GGX:
+ aniso->distribution = CLOSURE_BSDF_MICROFACET_MULTI_GGX_ANISO_ID;
+ break;
case BL::ShaderNodeBsdfAnisotropic::distribution_ASHIKHMIN_SHIRLEY:
aniso->distribution = CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID;
break;
@@ -439,6 +442,9 @@ static ShaderNode *add_node(Scene *scene,
case BL::ShaderNodeBsdfGlossy::distribution_ASHIKHMIN_SHIRLEY:
glossy->distribution = CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID;
break;
+ case BL::ShaderNodeBsdfGlossy::distribution_MULTI_GGX:
+ glossy->distribution = CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID;
+ break;
}
node = glossy;
}
@@ -455,6 +461,9 @@ static ShaderNode *add_node(Scene *scene,
case BL::ShaderNodeBsdfGlass::distribution_GGX:
glass->distribution = CLOSURE_BSDF_MICROFACET_GGX_GLASS_ID;
break;
+ case BL::ShaderNodeBsdfGlass::distribution_MULTI_GGX:
+ glass->distribution = CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID;
+ break;
}
node = glass;
}
diff --git a/intern/cycles/kernel/CMakeLists.txt b/intern/cycles/kernel/CMakeLists.txt
index ddf1243..f0adbc0 100644
--- a/intern/cycles/kernel/CMakeLists.txt
+++ b/intern/cycles/kernel/CMakeLists.txt
@@ -76,6 +76,8 @@ set(SRC_CLOSURE_HEADERS
closure/bsdf_diffuse.h
closure/bsdf_diffuse_ramp.h
closure/bsdf_microfacet.h
+ closure/bsdf_microfacet_multi.h
+ closure/bsdf_microfacet_multi_impl.h
closure/bsdf_oren_nayar.h
closure/bsdf_phong_ramp.h
closure/bsdf_reflection.h
diff --git a/intern/cycles/kernel/closure/bsdf.h b/intern/cycles/kernel/closure/bsdf.h
index f0add80..f318a61 100644
--- a/intern/cycles/kernel/closure/bsdf.h
+++ b/intern/cycles/kernel/closure/bsdf.h
@@ -20,6 +20,7 @@
#include "../closure/bsdf_phong_ramp.h"
#include "../closure/bsdf_diffuse_ramp.h"
#include "../closure/bsdf_microfacet.h"
+#include "../closure/bsdf_microfacet_multi.h"
#include "../closure/bsdf_reflection.h"
#include "../closure/bsdf_refraction.h"
#include "../closure/bsdf_transparent.h"
@@ -35,7 +36,7 @@
CCL_NAMESPACE_BEGIN
-ccl_device int bsdf_sample(KernelGlobals *kg, const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, differential3 *domega_in, float *pdf)
+ccl_device int bsdf_sample(KernelGlobals *kg, ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, differential3 *domega_in, float *pdf)
{
int label;
@@ -85,6 +86,14 @@ ccl_device int bsdf_sample(KernelGlobals *kg, const ShaderData *sd, const Shader
label = bsdf_microfacet_ggx_sample(kg, sc, ccl_fetch(sd, Ng), ccl_fetch(sd, I), ccl_fetch(sd, dI).dx, ccl_fetch(sd, dI).dy, randu, randv,
eval, omega_in, &domega_in->dx, &domega_in->dy, pdf);
break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID:
+ label = bsdf_microfacet_multi_ggx_sample(kg, sc, ccl_fetch(sd, Ng), ccl_fetch(sd, I), ccl_fetch(sd, dI).dx, ccl_fetch(sd, dI).dy, randu, randv,
+ eval, omega_in, &domega_in->dx, &domega_in->dy, pdf, &ccl_fetch(sd, lcg_state));
+ break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID:
+ label = bsdf_microfacet_multi_ggx_glass_sample(kg, sc, ccl_fetch(sd, Ng), ccl_fetch(sd, I), ccl_fetch(sd, dI).dx, ccl_fetch(sd, dI).dy, randu, randv,
+ eval, omega_in, &domega_in->dx, &domega_in->dy, pdf, &ccl_fetch(sd, lcg_state));
+ break;
case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
@@ -130,7 +139,7 @@ ccl_device int bsdf_sample(KernelGlobals *kg, const ShaderData *sd, const Shader
return label;
}
-ccl_device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const ShaderClosure *sc, const float3 omega_in, float *pdf)
+ccl_device float3 bsdf_eval(KernelGlobals *kg, ShaderData *sd, const ShaderClosure *sc, const float3 omega_in, float *pdf)
{
float3 eval;
@@ -172,6 +181,12 @@ ccl_device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const Shade
case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
eval = bsdf_microfacet_ggx_eval_reflect(sc, ccl_fetch(sd, I), omega_in, pdf);
break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID:
+ eval = bsdf_microfacet_multi_ggx_eval_reflect(sc, ccl_fetch(sd, I), omega_in, pdf, &ccl_fetch(sd, lcg_state));
+ break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID:
+ eval = bsdf_microfacet_multi_ggx_glass_eval_reflect(sc, ccl_fetch(sd, I), omega_in, pdf, &ccl_fetch(sd, lcg_state));
+ break;
case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
@@ -234,6 +249,12 @@ ccl_device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const Shade
case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
eval = bsdf_microfacet_ggx_eval_transmit(sc, ccl_fetch(sd, I), omega_in, pdf);
break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID:
+ eval = bsdf_microfacet_multi_ggx_eval_transmit(sc, ccl_fetch(sd, I), omega_in, pdf, &ccl_fetch(sd, lcg_state));
+ break;
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID:
+ eval = bsdf_microfacet_multi_ggx_glass_eval_transmit(sc, ccl_fetch(sd, I), omega_in, pdf, &ccl_fetch(sd, lcg_state));
+ break;
case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
@@ -286,6 +307,10 @@ ccl_device void bsdf_blur(KernelGlobals *kg, ShaderClosure *sc, float roughness)
#ifdef __SVM__
switch(sc->type) {
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID:
+ case CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID:
+ bsdf_microfacet_multi_ggx_blur(sc, roughness);
+ break;
case CLOSURE_BSDF_MICROFACET_GGX_ID:
case CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID:
case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
new file mode 100644
index 0000000..21fbfa9
--- /dev/null
+++ b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
@@ -0,0 +1,472 @@
+/*
+ * Copyright 2011-2016 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.
+ */
+
+CCL_NAMESPACE_BEGIN
+
+/* Most of the code is based on the supplemental implementations from https://eheitzresearch.wordpress.com/240-2/. */
+
+/* === GGX Microfacet distribution functions === */
+
+/* Isotropic GGX microfacet distribution */
+ccl_device_inline float D_ggx(float3 wm, float alpha)
+{
+ wm.z *= wm.z;
+ alpha *= alpha;
+ float tmp = (1.0f - wm.z) + alpha * wm.z;
+ return alpha / max(M_PI_F * tmp*tmp, 1e-7f);
+}
+
+/* Anisotropic GGX microfacet distribution */
+ccl_device_inline float D_ggx_aniso(const float3 wm, const float2 alpha)
+{
+ float slope_x = -wm.x/alpha.x;
+ float slope_y = -wm.y/alpha.y;
+ float tmp = wm.z*wm.z + slope_x*slope_x + slope_y*slope_y;
+
+ return 1.0f / max(M_PI_F * tmp*tmp * alpha.x*alpha.y, 1e-7f);
+}
+
+/* Sample slope distribution (based on page 14 of the supplemental implementation). */
+ccl_device_inline float2 mf_sampleP22_11(const float cosI, const float2 randU)
+{
+ if(cosI > 0.9999f) {
+ const float r = sqrtf(randU.x / (1.0f - randU.x));
+ const float phi = M_2PI_F * randU.y;
+ return make_float2(r*cosf(phi), r*sinf(phi));
+ }
+
+ const float sinI = sqrtf(1.0f - cosI*cosI);
+ const float tanI = sinI/cosI;
+ const float projA = 0.5f * (cosI + 1.0f);
+ if(projA < 0.0001f)
+ return make_float2(0.0f, 0.0f);
+ const float A = 2.0f*randU.x*projA / cosI - 1.0f;
+ float tmp = A*A-1.0f;
+ if(fabsf(tmp) < 1e-7f)
+ return make_float2(0.0f, 0.0f);
+ tmp = 1.0f / tmp;
+ const float D = safe_sqrtf(tanI*tanI*tmp*tmp - (A*A-tanI*tanI)*tmp);
+
+ const float slopeX2 = tanI*tmp + D;
+ const float slopeX = (A < 0.0f || slopeX2 > 1.0f/tanI)? (tanI*tmp - D) : slopeX2;
+
+ float U2;
+ if(randU.y >= 0.5f)
+ U2 = 2.0f*(randU.y - 0.5f);
+ else
+ U2 = 2.0f*(0.5f - randU.y);
+ const float z = (U2*(U2*(U2*0.27385f-0.73369f)+0.46341f)) / (U2*(U2*(U2*0.093073f+0.309420f)-1.0f)+0.597999f);
+ const float slopeY = z * sqrtf(1.0f + slopeX*slopeX);
+
+ if(randU.y >= 0.5f)
+ return make_float2(slopeX, slopeY);
+ else
+ return make_float2(slopeX, -slopeY);
+}
+
+/* Visible normal sampling for the GGX distribution (based on page 7 of the supplemental implementation). */
+ccl_device_inline float3 mf_sample_vndf(const float3 wi, const float2 alpha, const float2 randU)
+{
+ const float3 wi_11 = normalize(make_float3(alpha.x*wi.x, alpha.y*wi.y, wi.z));
+ const float2 slope_11 = mf_sampleP22_11(wi_11.z, randU);
+
+ const float2 cossin_phi = normalize(make_float2(wi_11.x, wi_11.y));
+ const float slope_x = alpha.x*(cossin_phi.x * slope_11.x - cossin_phi.y * slope_11.y);
+ const float slope_y = alpha.y*(cossin_phi.y * slope_11.x + cossin_phi.x * slope_11.y);
+
+ kernel_assert(isfinite(slope_x));
+ return normalize(make_float3(-slope_x, -slope_y, 1.0f));
+}
+
+/* === Phase functions: Glossy, Diffuse and Glass === */
+
+/* Phase function for reflective materials, either without a fresnel term (for compatibility) or with the conductive fresnel term. */
+ccl_device_inline float3 mf_sample_phase_glossy(const float3 wi, float3 *n, float3 *k, float3 *weight, const float3 wm)
+{
+
@@ Diff output truncated at 10240 characters. @@
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