456 lines
17 KiB
C
456 lines
17 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 *
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shadow_blocked_volume_path_state(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, shadow_sd, volume_state, &segment_ray, 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, shadow_sd, state, 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, *ray, visibility & PATH_RAY_SHADOW_OPAQUE, isect);
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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, ray, hits, visibility, max_hits, &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, &volume_state, state, sd, 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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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, &volume_state, state, sd, 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 = (Intersection *)malloc(sizeof(Intersection) *
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(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(
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kg, sd, shadow_sd, state, visibility, ray, hits, max_hits, 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(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, &volume_state, state, sd, 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, *ray, visibility & PATH_RAY_SHADOW_TRANSPARENT, isect)) {
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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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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, &volume_state, state, sd, 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(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, *ray, visibility & PATH_RAY_SHADOW_OPAQUE, isect);
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bool is_transparent_isect = blocked ? shader_transparent_shadow(kg, isect) : false;
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return shadow_blocked_transparent_stepped_loop(
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kg, sd, shadow_sd, state, visibility, ray, isect, blocked, is_transparent_isect, 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) ? 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, shadow_sd, state, visibility, ray, &isect, 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 tricky 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, *ray, visibility & PATH_RAY_SHADOW_OPAQUE, &isect);
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const bool is_transparent_isect = blocked ? shader_transparent_shadow(kg, &isect) : false;
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if (!blocked || !is_transparent_isect || max_hits + 1 >= SHADOW_STACK_MAX_HITS) {
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return shadow_blocked_transparent_stepped_loop(
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kg, sd, shadow_sd, state, visibility, ray, &isect, blocked, is_transparent_isect, shadow);
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}
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# endif /* __KERNEL_GPU__ */
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return shadow_blocked_transparent_all(
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kg, sd, shadow_sd, state, visibility, ray, max_hits, shadow);
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# else /* __SHADOW_RECORD_ALL__ */
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/* Fallback to a slowest version which works on all devices. */
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return shadow_blocked_transparent_stepped(
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kg, sd, shadow_sd, state, visibility, ray, &isect, shadow);
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# endif /* __SHADOW_RECORD_ALL__ */
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#endif /* __TRANSPARENT_SHADOWS__ */
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}
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#undef SHADOW_STACK_MAX_HITS
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CCL_NAMESPACE_END
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