forked from bartvdbraak/blender
422 lines
12 KiB
C
422 lines
12 KiB
C
/*
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* Copyright 2011, Blender Foundation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "kernel_differential.h"
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#include "kernel_montecarlo.h"
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#include "kernel_triangle.h"
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#include "kernel_object.h"
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#ifdef __QBVH__
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#include "kernel_qbvh.h"
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#else
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#include "kernel_bvh.h"
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#endif
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#include "kernel_camera.h"
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#include "kernel_shader.h"
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#include "kernel_light.h"
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#include "kernel_emission.h"
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#include "kernel_random.h"
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CCL_NAMESPACE_BEGIN
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#ifdef __MODIFY_TP__
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__device float3 path_terminate_modified_throughput(KernelGlobals *kg, __global float3 *buffer, int x, int y, int sample)
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{
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/* modify throughput to influence path termination probability, to avoid
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darker regions receiving fewer samples than lighter regions. also RGB
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are weighted differently. proper validation still remains to be done. */
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const float3 weights = make_float3(1.0f, 1.33f, 0.66f);
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const float3 one = make_float3(1.0f, 1.0f, 1.0f);
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const int minsample = 5;
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const float minL = 0.1f;
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if(sample >= minsample) {
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float3 L = buffer[x + y*kernel_data.cam.width];
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float3 Lmin = make_float3(minL, minL, minL);
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float correct = (float)(sample+1)/(float)sample;
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L = film_map(L*correct, sample);
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return weights/clamp(L, Lmin, one);
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}
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return weights;
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}
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#endif
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typedef struct PathState {
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uint flag;
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int bounce;
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int diffuse_bounce;
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int glossy_bounce;
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int transmission_bounce;
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int transparent_bounce;
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} PathState;
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__device_inline void path_state_init(PathState *state)
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{
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state->flag = PATH_RAY_CAMERA|PATH_RAY_SINGULAR|PATH_RAY_MIS_SKIP;
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state->bounce = 0;
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state->diffuse_bounce = 0;
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state->glossy_bounce = 0;
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state->transmission_bounce = 0;
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state->transparent_bounce = 0;
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}
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__device_inline void path_state_next(KernelGlobals *kg, PathState *state, int label)
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{
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/* ray through transparent keeps same flags from previous ray and is
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not counted as a regular bounce, transparent has separate max */
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if(label & LABEL_TRANSPARENT) {
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state->flag |= PATH_RAY_TRANSPARENT;
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state->transparent_bounce++;
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if(!kernel_data.integrator.transparent_shadows)
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state->flag |= PATH_RAY_MIS_SKIP;
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return;
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}
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state->bounce++;
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/* reflection/transmission */
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if(label & LABEL_REFLECT) {
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state->flag |= PATH_RAY_REFLECT;
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state->flag &= ~(PATH_RAY_TRANSMIT|PATH_RAY_CAMERA|PATH_RAY_TRANSPARENT);
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if(label & LABEL_DIFFUSE)
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state->diffuse_bounce++;
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else
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state->glossy_bounce++;
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}
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else {
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kernel_assert(label & LABEL_TRANSMIT);
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state->flag |= PATH_RAY_TRANSMIT;
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state->flag &= ~(PATH_RAY_REFLECT|PATH_RAY_CAMERA|PATH_RAY_TRANSPARENT);
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state->transmission_bounce++;
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}
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/* diffuse/glossy/singular */
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if(label & LABEL_DIFFUSE) {
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state->flag |= PATH_RAY_DIFFUSE;
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state->flag &= ~(PATH_RAY_GLOSSY|PATH_RAY_SINGULAR|PATH_RAY_MIS_SKIP);
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}
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else if(label & LABEL_GLOSSY) {
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state->flag |= PATH_RAY_GLOSSY;
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state->flag &= ~(PATH_RAY_DIFFUSE|PATH_RAY_SINGULAR|PATH_RAY_MIS_SKIP);
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}
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else {
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kernel_assert(label & LABEL_SINGULAR);
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state->flag |= PATH_RAY_GLOSSY|PATH_RAY_SINGULAR|PATH_RAY_MIS_SKIP;
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state->flag &= ~PATH_RAY_DIFFUSE;
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}
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}
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__device_inline uint path_state_ray_visibility(PathState *state)
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{
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uint flag = state->flag;
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/* for visibility, diffuse/glossy are for reflection only */
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if(flag & PATH_RAY_TRANSMIT)
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flag &= ~(PATH_RAY_DIFFUSE|PATH_RAY_GLOSSY);
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return flag;
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}
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__device_inline float path_state_terminate_probability(KernelGlobals *kg, PathState *state, const float3 throughput)
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{
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if(state->flag & PATH_RAY_TRANSPARENT) {
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/* transparent rays treated separately */
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if(state->transparent_bounce >= kernel_data.integrator.transparent_max_bounce)
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return 0.0f;
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else if(state->transparent_bounce <= kernel_data.integrator.transparent_min_bounce)
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return 1.0f;
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}
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else {
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/* other rays */
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if((state->bounce >= kernel_data.integrator.max_bounce) ||
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(state->diffuse_bounce >= kernel_data.integrator.max_diffuse_bounce) ||
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(state->glossy_bounce >= kernel_data.integrator.max_glossy_bounce) ||
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(state->transmission_bounce >= kernel_data.integrator.max_transmission_bounce))
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return 0.0f;
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else if(state->bounce <= kernel_data.integrator.min_bounce)
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return 1.0f;
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}
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/* probalistic termination */
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return average(throughput);
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}
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__device_inline bool shadow_blocked(KernelGlobals *kg, PathState *state, Ray *ray, Intersection *isect, float3 *light_L)
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{
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if(ray->t == 0.0f)
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return false;
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bool result = scene_intersect(kg, ray, PATH_RAY_SHADOW_OPAQUE, isect);
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#ifdef __TRANSPARENT_SHADOWS__
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if(result && kernel_data.integrator.transparent_shadows) {
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/* transparent shadows work in such a way to try to minimize overhead
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in cases where we don't need them. after a regular shadow ray is
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cast we check if the hit primitive was potentially transparent, and
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only in that case start marching. this gives on extra ray cast for
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the cases were we do want transparency.
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also note that for this to work correct, multi close sampling must
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be used, since we don't pass a random number to shader_eval_surface */
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if(shader_transparent_shadow(kg, isect)) {
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float3 throughput = make_float3(1.0f, 1.0f, 1.0f);
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float3 Pend = ray->P + ray->D*ray->t;
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int bounce = state->transparent_bounce;
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for(;;) {
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if(bounce >= kernel_data.integrator.transparent_max_bounce) {
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return true;
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}
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else if(bounce >= kernel_data.integrator.transparent_min_bounce) {
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/* todo: get random number somewhere for probabilistic terminate */
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#if 0
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float probability = average(throughput);
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float terminate = 0.0f;
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if(terminate >= probability)
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return true;
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throughput /= probability;
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#endif
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}
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if(!scene_intersect(kg, ray, PATH_RAY_SHADOW_TRANSPARENT, isect)) {
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*light_L *= throughput;
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return false;
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}
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if(!shader_transparent_shadow(kg, isect))
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return true;
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ShaderData sd;
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shader_setup_from_ray(kg, &sd, isect, ray);
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shader_eval_surface(kg, &sd, 0.0f, PATH_RAY_SHADOW);
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throughput *= shader_bsdf_transparency(kg, &sd);
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ray->P = ray_offset(sd.P, -sd.Ng);
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if(ray->t != FLT_MAX)
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ray->D = normalize_len(Pend - ray->P, &ray->t);
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bounce++;
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}
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}
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}
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#endif
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return result;
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}
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__device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample, Ray ray, float3 throughput)
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{
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/* initialize */
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float3 L = make_float3(0.0f, 0.0f, 0.0f);
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float Ltransparent = 0.0f;
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#ifdef __EMISSION__
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float ray_pdf = 0.0f;
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#endif
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PathState state;
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int rng_offset = PRNG_BASE_NUM;
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path_state_init(&state);
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/* path iteration */
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for(;; rng_offset += PRNG_BOUNCE_NUM) {
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/* intersect scene */
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Intersection isect;
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uint visibility = path_state_ray_visibility(&state);
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if(!scene_intersect(kg, &ray, visibility, &isect)) {
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/* eval background shader if nothing hit */
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if(kernel_data.background.transparent && (state.flag & PATH_RAY_CAMERA)) {
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Ltransparent += average(throughput);
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}
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else {
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#ifdef __BACKGROUND__
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ShaderData sd;
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shader_setup_from_background(kg, &sd, &ray);
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L += throughput*shader_eval_background(kg, &sd, state.flag);
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shader_release(kg, &sd);
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#else
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L += throughput*make_float3(0.8f, 0.8f, 0.8f);
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#endif
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}
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break;
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}
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/* setup shading */
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ShaderData sd;
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shader_setup_from_ray(kg, &sd, &isect, &ray);
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float rbsdf = path_rng(kg, rng, sample, rng_offset + PRNG_BSDF);
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shader_eval_surface(kg, &sd, rbsdf, state.flag);
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#ifdef __HOLDOUT__
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if((sd.flag & SD_HOLDOUT) && (state.flag & PATH_RAY_CAMERA)) {
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float3 holdout_weight = shader_holdout_eval(kg, &sd);
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if(kernel_data.background.transparent)
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Ltransparent += average(holdout_weight*throughput);
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}
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#endif
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#ifdef __EMISSION__
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/* emission */
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if(sd.flag & SD_EMISSION)
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L += throughput*indirect_emission(kg, &sd, isect.t, state.flag, ray_pdf);
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#endif
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/* path termination. this is a strange place to put the termination, it's
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mainly due to the mixed in MIS that we use. gives too many unneeded
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shader evaluations, only need emission if we are going to terminate */
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float probability = path_state_terminate_probability(kg, &state, throughput);
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float terminate = path_rng(kg, rng, sample, rng_offset + PRNG_TERMINATE);
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if(terminate >= probability)
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break;
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throughput /= probability;
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#ifdef __EMISSION__
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if(kernel_data.integrator.use_direct_light) {
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/* sample illumination from lights to find path contribution */
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if(sd.flag & SD_BSDF_HAS_EVAL) {
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float light_t = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT);
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float light_o = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT_F);
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float light_u = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT_U);
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float light_v = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT_V);
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Ray light_ray;
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float3 light_L;
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#ifdef __MULTI_LIGHT__
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/* index -1 means randomly sample from distribution */
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int i = (kernel_data.integrator.num_distribution)? -1: 0;
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for(; i < kernel_data.integrator.num_all_lights; i++) {
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#else
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const int i = -1;
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#endif
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if(direct_emission(kg, &sd, i, light_t, light_o, light_u, light_v, &light_ray, &light_L)) {
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/* trace shadow ray */
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if(!shadow_blocked(kg, &state, &light_ray, &isect, &light_L))
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L += throughput*light_L;
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}
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#ifdef __MULTI_LIGHT__
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}
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#endif
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}
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}
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#endif
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/* no BSDF? we can stop here */
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if(!(sd.flag & SD_BSDF))
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break;
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/* sample BSDF */
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float bsdf_pdf;
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float3 bsdf_eval;
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float3 bsdf_omega_in;
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differential3 bsdf_domega_in;
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float bsdf_u = path_rng(kg, rng, sample, rng_offset + PRNG_BSDF_U);
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float bsdf_v = path_rng(kg, rng, sample, rng_offset + PRNG_BSDF_V);
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int label;
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label = shader_bsdf_sample(kg, &sd, bsdf_u, bsdf_v, &bsdf_eval,
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&bsdf_omega_in, &bsdf_domega_in, &bsdf_pdf);
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shader_release(kg, &sd);
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if(bsdf_pdf == 0.0f || is_zero(bsdf_eval))
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break;
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/* modify throughput */
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throughput *= bsdf_eval/bsdf_pdf;
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/* set labels */
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#ifdef __EMISSION__
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ray_pdf = bsdf_pdf;
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#endif
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/* update path state */
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path_state_next(kg, &state, label);
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/* setup ray */
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ray.P = ray_offset(sd.P, (label & LABEL_TRANSMIT)? -sd.Ng: sd.Ng);
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ray.D = bsdf_omega_in;
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ray.t = FLT_MAX;
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#ifdef __RAY_DIFFERENTIALS__
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ray.dP = sd.dP;
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ray.dD = bsdf_domega_in;
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#endif
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}
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return make_float4(L.x, L.y, L.z, 1.0f - Ltransparent);
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}
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__device void kernel_path_trace(KernelGlobals *kg, __global float4 *buffer, __global uint *rng_state, int sample, int x, int y)
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{
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/* initialize random numbers */
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RNG rng;
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float filter_u;
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float filter_v;
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path_rng_init(kg, rng_state, sample, &rng, x, y, &filter_u, &filter_v);
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/* sample camera ray */
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Ray ray;
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float lens_u = path_rng(kg, &rng, sample, PRNG_LENS_U);
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float lens_v = path_rng(kg, &rng, sample, PRNG_LENS_V);
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camera_sample(kg, x, y, filter_u, filter_v, lens_u, lens_v, &ray);
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/* integrate */
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#ifdef __MODIFY_TP__
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float3 throughput = path_terminate_modified_throughput(kg, buffer, x, y, sample);
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float4 L = kernel_path_integrate(kg, &rng, sample, ray, throughput)/throughput;
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#else
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float3 throughput = make_float3(1.0f, 1.0f, 1.0f);
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float4 L = kernel_path_integrate(kg, &rng, sample, ray, throughput);
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#endif
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/* accumulate result in output buffer */
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int index = x + y*kernel_data.cam.width;
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if(sample == 0)
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buffer[index] = L;
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else
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buffer[index] += L;
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path_rng_end(kg, rng_state, rng, x, y);
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}
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CCL_NAMESPACE_END
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