forked from bartvdbraak/blender
Brecht Van Lommel
2d81758aa6
We now continue transparent paths after diffuse/glossy/transmission/volume bounces are exceeded. This avoids unexpected boundaries in volumes with transparent boundaries. It is also required for MIS to work correctly with transparent surfaces, as we also continue through these in shadow rays. The main visible changes is that volumes will now be lit by the background even at volume bounces 0, same as surfaces. Fixes T53914 and T54103.
557 lines
20 KiB
C
557 lines
20 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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#ifdef __VOLUME__
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typedef struct VolumeState {
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# ifdef __SPLIT_KERNEL__
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# else
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PathState ps;
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# endif
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} VolumeState;
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/* Get PathState ready for use for volume stack evaluation. */
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space
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# endif
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ccl_device_inline PathState *shadow_blocked_volume_path_state(
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KernelGlobals *kg,
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VolumeState *volume_state,
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ccl_addr_space PathState *state,
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ShaderData *sd,
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Ray *ray)
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{
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space PathState *ps =
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&kernel_split_state.state_shadow[ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0)];
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# else
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PathState *ps = &volume_state->ps;
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# endif
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*ps = *state;
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/* We are checking for shadow on the "other" side of the surface, so need
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* to discard volume we are currently at.
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*/
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if(dot(sd->Ng, ray->D) < 0.0f) {
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kernel_volume_stack_enter_exit(kg, sd, ps->volume_stack);
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}
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return ps;
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}
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#endif /* __VOLUME__ */
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/* Attenuate throughput accordingly to the given intersection event.
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* Returns true if the throughput is zero and traversal can be aborted.
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*/
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ccl_device_forceinline bool shadow_handle_transparent_isect(
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KernelGlobals *kg,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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# ifdef __VOLUME__
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ccl_addr_space struct PathState *volume_state,
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# endif
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Intersection *isect,
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Ray *ray,
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float3 *throughput)
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{
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#ifdef __VOLUME__
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/* Attenuation between last surface and next surface. */
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if(volume_state->volume_stack[0].shader != SHADER_NONE) {
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Ray segment_ray = *ray;
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segment_ray.t = isect->t;
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kernel_volume_shadow(kg,
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shadow_sd,
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volume_state,
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&segment_ray,
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throughput);
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}
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#endif
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/* Setup shader data at surface. */
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shader_setup_from_ray(kg, shadow_sd, isect, ray);
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/* Attenuation from transparent surface. */
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if(!(shadow_sd->flag & SD_HAS_ONLY_VOLUME)) {
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path_state_modify_bounce(state, true);
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shader_eval_surface(kg,
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shadow_sd,
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state,
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PATH_RAY_SHADOW);
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path_state_modify_bounce(state, false);
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*throughput *= shader_bsdf_transparency(kg, shadow_sd);
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}
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/* Stop if all light is blocked. */
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if(is_zero(*throughput)) {
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return true;
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}
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#ifdef __VOLUME__
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/* Exit/enter volume. */
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kernel_volume_stack_enter_exit(kg, shadow_sd, volume_state->volume_stack);
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#endif
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return false;
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}
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/* Special version which only handles opaque shadows. */
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ccl_device bool shadow_blocked_opaque(KernelGlobals *kg,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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const uint visibility,
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Ray *ray,
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Intersection *isect,
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float3 *shadow)
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{
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const bool blocked = scene_intersect(kg,
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*ray,
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visibility & PATH_RAY_SHADOW_OPAQUE,
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isect,
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NULL,
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0.0f, 0.0f);
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#ifdef __VOLUME__
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if(!blocked && state->volume_stack[0].shader != SHADER_NONE) {
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/* Apply attenuation from current volume shader. */
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kernel_volume_shadow(kg, shadow_sd, state, ray, shadow);
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}
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#endif
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return blocked;
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}
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#ifdef __TRANSPARENT_SHADOWS__
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# ifdef __SHADOW_RECORD_ALL__
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/* Shadow function to compute how much light is blocked,
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*
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* We trace a single ray. If it hits any opaque surface, or more than a given
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* number of transparent surfaces is hit, then we consider the geometry to be
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* entirely blocked. If not, all transparent surfaces will be recorded and we
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* will shade them one by one to determine how much light is blocked. This all
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* happens in one scene intersection function.
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*
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* Recording all hits works well in some cases but may be slower in others. If
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* we have many semi-transparent hairs, one intersection may be faster because
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* you'd be reinteresecting the same hairs a lot with each step otherwise. If
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* however there is mostly binary transparency then we may be recording many
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* unnecessary intersections when one of the first surfaces blocks all light.
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*
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* From tests in real scenes it seems the performance loss is either minimal,
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* or there is a performance increase anyway due to avoiding the need to send
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* two rays with transparent shadows.
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*
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* On CPU it'll handle all transparent bounces (by allocating storage for
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* intersections when they don't fit into the stack storage).
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*
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* On GPU it'll only handle SHADOW_STACK_MAX_HITS-1 intersections, so this
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* is something to be kept an eye on.
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*/
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# define SHADOW_STACK_MAX_HITS 64
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/* Actual logic with traversal loop implementation which is free from device
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* specific tweaks.
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*
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* Note that hits array should be as big as max_hits+1.
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*/
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ccl_device bool shadow_blocked_transparent_all_loop(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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const uint visibility,
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Ray *ray,
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Intersection *hits,
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uint max_hits,
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float3 *shadow)
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{
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/* Intersect to find an opaque surface, or record all transparent
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* surface hits.
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*/
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uint num_hits;
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const bool blocked = scene_intersect_shadow_all(kg,
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ray,
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hits,
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visibility,
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max_hits,
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&num_hits);
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# ifdef __VOLUME__
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VolumeState volume_state;
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# endif
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/* If no opaque surface found but we did find transparent hits,
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* shade them.
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*/
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if(!blocked && num_hits > 0) {
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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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float last_t = 0.0f;
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int bounce = state->transparent_bounce;
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Intersection *isect = hits;
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# ifdef __VOLUME__
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space
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# endif
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PathState *ps = shadow_blocked_volume_path_state(kg,
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&volume_state,
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state,
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sd,
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ray);
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# endif
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sort_intersections(hits, num_hits);
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for(int hit = 0; hit < num_hits; hit++, isect++) {
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/* Adjust intersection distance for moving ray forward. */
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float new_t = isect->t;
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isect->t -= last_t;
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/* Skip hit if we did not move forward, step by step raytracing
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* would have skipped it as well then.
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*/
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if(last_t == new_t) {
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continue;
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}
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last_t = new_t;
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/* Attenuate the throughput. */
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if(shadow_handle_transparent_isect(kg,
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shadow_sd,
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state,
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#ifdef __VOLUME__
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ps,
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#endif
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isect,
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ray,
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&throughput))
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{
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return true;
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}
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/* Move ray forward. */
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ray->P = shadow_sd->P;
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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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}
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bounce++;
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}
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# ifdef __VOLUME__
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/* Attenuation for last line segment towards light. */
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if(ps->volume_stack[0].shader != SHADER_NONE) {
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kernel_volume_shadow(kg, shadow_sd, ps, ray, &throughput);
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}
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# endif
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*shadow = throughput;
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return is_zero(throughput);
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}
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# ifdef __VOLUME__
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if(!blocked && state->volume_stack[0].shader != SHADER_NONE) {
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/* Apply attenuation from current volume shader. */
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space
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# endif
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PathState *ps = shadow_blocked_volume_path_state(kg,
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&volume_state,
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state,
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sd,
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ray);
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kernel_volume_shadow(kg, shadow_sd, ps, ray, shadow);
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}
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# endif
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return blocked;
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}
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/* Here we do all device specific trickery before invoking actual traversal
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* loop to help readability of the actual logic.
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*/
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ccl_device bool shadow_blocked_transparent_all(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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const uint visibility,
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Ray *ray,
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uint max_hits,
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float3 *shadow)
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{
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# ifdef __SPLIT_KERNEL__
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Intersection hits_[SHADOW_STACK_MAX_HITS];
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Intersection *hits = &hits_[0];
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# elif defined(__KERNEL_CUDA__)
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Intersection *hits = kg->hits_stack;
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# else
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Intersection hits_stack[SHADOW_STACK_MAX_HITS];
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Intersection *hits = hits_stack;
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# endif
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# ifndef __KERNEL_GPU__
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/* Prefer to use stack but use dynamic allocation if too deep max hits
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* we need max_hits + 1 storage space due to the logic in
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* scene_intersect_shadow_all which will first store and then check if
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* the limit is exceeded.
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*
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* Ignore this on GPU because of slow/unavailable malloc().
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*/
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if(max_hits + 1 > SHADOW_STACK_MAX_HITS) {
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if(kg->transparent_shadow_intersections == NULL) {
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const int transparent_max_bounce = kernel_data.integrator.transparent_max_bounce;
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kg->transparent_shadow_intersections =
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(Intersection*)malloc(sizeof(Intersection)*(transparent_max_bounce + 1));
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}
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hits = kg->transparent_shadow_intersections;
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}
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# endif /* __KERNEL_GPU__ */
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/* Invoke actual traversal. */
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return shadow_blocked_transparent_all_loop(kg,
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sd,
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shadow_sd,
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state,
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visibility,
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ray,
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hits,
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max_hits,
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shadow);
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}
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# endif /* __SHADOW_RECORD_ALL__ */
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# if defined(__KERNEL_GPU__) || !defined(__SHADOW_RECORD_ALL__)
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/* Shadow function to compute how much light is blocked,
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*
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* Here we raytrace from one transparent surface to the next step by step.
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* To minimize overhead in cases where we don't need transparent shadows, we
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* first trace a regular shadow ray. We check if the hit primitive was
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* potentially transparent, and only in that case start marching. this gives
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* one extra ray cast for the cases were we do want transparency.
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*/
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/* This function is only implementing device-independent traversal logic
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* which requires some precalculation done.
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*/
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ccl_device bool shadow_blocked_transparent_stepped_loop(
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KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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const uint visibility,
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Ray *ray,
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Intersection *isect,
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const bool blocked,
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const bool is_transparent_isect,
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float3 *shadow)
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{
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# ifdef __VOLUME__
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VolumeState volume_state;
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# endif
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if(blocked && is_transparent_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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# ifdef __VOLUME__
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space
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# endif
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PathState *ps = shadow_blocked_volume_path_state(kg,
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&volume_state,
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state,
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sd,
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ray);
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# endif
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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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if(!scene_intersect(kg,
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*ray,
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visibility & PATH_RAY_SHADOW_TRANSPARENT,
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isect,
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NULL,
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0.0f, 0.0f))
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{
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break;
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}
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if(!shader_transparent_shadow(kg, isect)) {
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return true;
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}
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/* Attenuate the throughput. */
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if(shadow_handle_transparent_isect(kg,
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shadow_sd,
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state,
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#ifdef __VOLUME__
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ps,
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#endif
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isect,
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ray,
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&throughput))
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{
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return true;
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}
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/* Move ray forward. */
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ray->P = ray_offset(shadow_sd->P, -shadow_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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}
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bounce++;
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}
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# ifdef __VOLUME__
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/* Attenuation for last line segment towards light. */
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if(ps->volume_stack[0].shader != SHADER_NONE) {
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kernel_volume_shadow(kg, shadow_sd, ps, ray, &throughput);
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}
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# endif
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*shadow *= throughput;
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return is_zero(throughput);
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}
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# ifdef __VOLUME__
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if(!blocked && state->volume_stack[0].shader != SHADER_NONE) {
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/* Apply attenuation from current volume shader. */
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# ifdef __SPLIT_KERNEL__
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ccl_addr_space
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# endif
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PathState *ps = shadow_blocked_volume_path_state(kg,
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&volume_state,
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state,
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sd,
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ray);
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kernel_volume_shadow(kg, shadow_sd, ps, ray, shadow);
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}
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# endif
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return blocked;
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}
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ccl_device bool shadow_blocked_transparent_stepped(
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KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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const uint visibility,
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Ray *ray,
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Intersection *isect,
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float3 *shadow)
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{
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bool blocked = scene_intersect(kg,
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*ray,
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visibility & PATH_RAY_SHADOW_OPAQUE,
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isect,
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NULL,
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0.0f, 0.0f);
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bool is_transparent_isect = blocked
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? shader_transparent_shadow(kg, isect)
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: false;
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return shadow_blocked_transparent_stepped_loop(kg,
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sd,
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shadow_sd,
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state,
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visibility,
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ray,
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isect,
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blocked,
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is_transparent_isect,
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shadow);
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}
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# endif /* __KERNEL_GPU__ || !__SHADOW_RECORD_ALL__ */
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#endif /* __TRANSPARENT_SHADOWS__ */
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ccl_device_inline bool shadow_blocked(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *shadow_sd,
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ccl_addr_space PathState *state,
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Ray *ray_input,
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float3 *shadow)
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{
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Ray *ray = ray_input;
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Intersection isect;
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/* Some common early checks. */
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*shadow = make_float3(1.0f, 1.0f, 1.0f);
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if(ray->t == 0.0f) {
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return false;
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}
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#ifdef __SHADOW_TRICKS__
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const uint visibility = (state->flag & PATH_RAY_SHADOW_CATCHER)
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? PATH_RAY_SHADOW_NON_CATCHER
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: PATH_RAY_SHADOW;
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#else
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const uint visibility = PATH_RAY_SHADOW;
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#endif
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/* Do actual shadow shading. */
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/* First of all, we check if integrator requires transparent shadows.
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* if not, we use simplest and fastest ever way to calculate occlusion.
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*/
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#ifdef __TRANSPARENT_SHADOWS__
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if(!kernel_data.integrator.transparent_shadows)
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#endif
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{
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return shadow_blocked_opaque(kg,
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shadow_sd,
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state,
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visibility,
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ray,
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&isect,
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shadow);
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}
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#ifdef __TRANSPARENT_SHADOWS__
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# ifdef __SHADOW_RECORD_ALL__
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/* For the transparent shadows we try to use record-all logic on the
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* devices which supports this.
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*/
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const int transparent_max_bounce = kernel_data.integrator.transparent_max_bounce;
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/* Check transparent bounces here, for volume scatter which can do
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* lighting before surface path termination is checked.
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*/
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if(state->transparent_bounce >= transparent_max_bounce) {
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return true;
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}
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const uint max_hits = transparent_max_bounce - state->transparent_bounce - 1;
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# ifdef __KERNEL_GPU__
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/* On GPU we do trickey with tracing opaque ray first, this avoids speed
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* regressions in some files.
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*
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* TODO(sergey): Check why using record-all behavior causes slowdown in such
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* cases. Could that be caused by a higher spill pressure?
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*/
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const bool blocked = scene_intersect(kg,
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*ray,
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visibility & PATH_RAY_SHADOW_OPAQUE,
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&isect,
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NULL,
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0.0f, 0.0f);
|
|
const bool is_transparent_isect = blocked
|
|
? shader_transparent_shadow(kg, &isect)
|
|
: false;
|
|
if(!blocked || !is_transparent_isect ||
|
|
max_hits + 1 >= SHADOW_STACK_MAX_HITS)
|
|
{
|
|
return shadow_blocked_transparent_stepped_loop(kg,
|
|
sd,
|
|
shadow_sd,
|
|
state,
|
|
visibility,
|
|
ray,
|
|
&isect,
|
|
blocked,
|
|
is_transparent_isect,
|
|
shadow);
|
|
}
|
|
# endif /* __KERNEL_GPU__ */
|
|
return shadow_blocked_transparent_all(kg,
|
|
sd,
|
|
shadow_sd,
|
|
state,
|
|
visibility,
|
|
ray,
|
|
max_hits,
|
|
shadow);
|
|
# else /* __SHADOW_RECORD_ALL__ */
|
|
/* Fallback to a slowest version which works on all devices. */
|
|
return shadow_blocked_transparent_stepped(kg,
|
|
sd,
|
|
shadow_sd,
|
|
state,
|
|
visibility,
|
|
ray,
|
|
&isect,
|
|
shadow);
|
|
# endif /* __SHADOW_RECORD_ALL__ */
|
|
#endif /* __TRANSPARENT_SHADOWS__ */
|
|
}
|
|
|
|
#undef SHADOW_STACK_MAX_HITS
|
|
|
|
CCL_NAMESPACE_END
|