forked from bartvdbraak/blender
26bf230920
In scenes with many lights, some of them might have a very small contribution to some pixels, but the shadow rays are traced anyways. To avoid that, this patch adds probabilistic termination to light samples - if the contribution before checking for shadowing is below a user-defined threshold, the sample will be discarded with probability (1 - (contribution / threshold)) and otherwise kept, but weighted more to remain unbiased. This is the same approach that's also used in path termination based on length. Note that the rendering remains unbiased with this option, it just adds a bit of noise - but if the setting is used moderately, the speedup gained easily outweighs the additional noise. Reviewers: #cycles Subscribers: sergey, brecht Differential Revision: https://developer.blender.org/D2217
109 lines
4.8 KiB
C
109 lines
4.8 KiB
C
/*
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* Copyright 2011-2015 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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#include "kernel_split_common.h"
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/* Note on kernel_direct_lighting kernel.
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* This is the eighth kernel in the ray tracing logic. This is the seventh
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* of the path iteration kernels. This kernel takes care of direct lighting
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* logic. However, the "shadow ray cast" part of direct lighting is handled
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* in the next kernel.
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*
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* This kernels determines the rays for which a shadow_blocked() function associated with direct lighting should be executed.
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* Those rays for which a shadow_blocked() function for direct-lighting must be executed, are marked with flag RAY_SHADOW_RAY_CAST_DL and
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* enqueued into the queue QUEUE_SHADOW_RAY_CAST_DL_RAYS
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*
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* The input and output are as follows,
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*
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* rng_coop -----------------------------------------|--- kernel_direct_lighting --|--- BSDFEval_coop
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* PathState_coop -----------------------------------| |--- ISLamp_coop
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* sd -----------------------------------------------| |--- LightRay_coop
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* ray_state ----------------------------------------| |--- ray_state
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* Queue_data (QUEUE_ACTIVE_AND_REGENERATED_RAYS) ---| |
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* kg (globals) -------------------------------------| |
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* queuesize ----------------------------------------| |
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*
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* Note on Queues :
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* This kernel only reads from the QUEUE_ACTIVE_AND_REGENERATED_RAYS queue and processes
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* only the rays of state RAY_ACTIVE; If a ray needs to execute the corresponding shadow_blocked
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* part, after direct lighting, the ray is marked with RAY_SHADOW_RAY_CAST_DL flag.
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*
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* State of queues when this kernel is called :
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* state of queues QUEUE_ACTIVE_AND_REGENERATED_RAYS and QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be same
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* before and after this kernel call.
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* QUEUE_SHADOW_RAY_CAST_DL_RAYS queue will be filled with rays for which a shadow_blocked function must be executed, after this
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* kernel call. Before this kernel call the QUEUE_SHADOW_RAY_CAST_DL_RAYS will be empty.
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*/
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ccl_device char kernel_direct_lighting(
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KernelGlobals *kg,
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ShaderData *sd, /* Required for direct lighting */
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ccl_global uint *rng_coop, /* Required for direct lighting */
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ccl_global PathState *PathState_coop, /* Required for direct lighting */
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ccl_global int *ISLamp_coop, /* Required for direct lighting */
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ccl_global Ray *LightRay_coop, /* Required for direct lighting */
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ccl_global BsdfEval *BSDFEval_coop, /* Required for direct lighting */
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ccl_global char *ray_state, /* Denotes the state of each ray */
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int ray_index)
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{
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char enqueue_flag = 0;
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if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
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ccl_global PathState *state = &PathState_coop[ray_index];
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/* direct lighting */
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#ifdef __EMISSION__
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if((kernel_data.integrator.use_direct_light &&
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(ccl_fetch(sd, flag) & SD_BSDF_HAS_EVAL)))
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{
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/* Sample illumination from lights to find path contribution. */
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ccl_global RNG* rng = &rng_coop[ray_index];
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float light_t = path_state_rng_1D(kg, rng, state, PRNG_LIGHT);
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float light_u, light_v;
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path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
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float terminate = path_state_rng_light_termination(kg, rng, state);
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LightSample ls;
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if(light_sample(kg,
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light_t, light_u, light_v,
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ccl_fetch(sd, time),
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ccl_fetch(sd, P),
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state->bounce,
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&ls)) {
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Ray light_ray;
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#ifdef __OBJECT_MOTION__
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light_ray.time = ccl_fetch(sd, time);
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#endif
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BsdfEval L_light;
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bool is_lamp;
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if(direct_emission(kg, sd, kg->sd_input, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
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/* Write intermediate data to global memory to access from
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* the next kernel.
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*/
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LightRay_coop[ray_index] = light_ray;
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BSDFEval_coop[ray_index] = L_light;
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ISLamp_coop[ray_index] = is_lamp;
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/* Mark ray state for next shadow kernel. */
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ADD_RAY_FLAG(ray_state, ray_index, RAY_SHADOW_RAY_CAST_DL);
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enqueue_flag = 1;
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}
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}
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}
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#endif /* __EMISSION__ */
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}
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return enqueue_flag;
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}
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