forked from bartvdbraak/blender
Brecht Van Lommel
e369a5c485
This is the simplest possible volume rendering case, constant density inside the volume and no scattering or emission. My plan is to tweak, verify and commit more volume rendering effects one by one, doing it all at once makes it difficult to verify correctness and track down bugs. Documentation is here: http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Materials/Volume Currently this hooks into path tracing in 3 ways, which should get us pretty far until we add more advanced light sampling. These 3 hooks are repeated in the path tracing, branched path tracing and transparent shadow code: * Determine active volume shader at start of the path * Change active volume shader on transmission through a surface * Light attenuation over line segments between camera, surfaces and background This is work by "storm", Stuart Broadfoot, Thomas Dinges and myself.
143 lines
4.0 KiB
C
143 lines
4.0 KiB
C
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License
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*/
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CCL_NAMESPACE_BEGIN
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typedef struct PathState {
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int 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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#ifdef __VOLUME__
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int volume_shader;
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#endif
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} PathState;
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ccl_device_inline void path_state_init(KernelGlobals *kg, 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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#ifdef __VOLUME__
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/* todo: this assumes camera is always in air, need to detect when it isn't */
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state->volume_shader = kernel_data.background.volume_shader;
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#endif
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}
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ccl_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|PATH_RAY_DIFFUSE_ANCESTOR;
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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|PATH_RAY_GLOSSY_ANCESTOR;
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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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ccl_device_inline uint path_state_ray_visibility(KernelGlobals *kg, PathState *state)
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{
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uint flag = state->flag & PATH_RAY_ALL_VISIBILITY;
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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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/* for camera visibility, use render layer flags */
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if(flag & PATH_RAY_CAMERA)
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flag |= kernel_data.integrator.layer_flag;
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return flag;
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}
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ccl_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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{
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return 0.0f;
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}
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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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}
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/* probalistic termination */
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return average(throughput); /* todo: try using max here */
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}
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CCL_NAMESPACE_END
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