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/*
* Copyright 2011-2021 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
CCL_NAMESPACE_BEGIN
/* Visibility for the shadow ray. */
ccl_device_forceinline uint integrate_intersect_shadow_visibility(KernelGlobals kg,
ConstIntegratorShadowState state)
{
uint visibility = PATH_RAY_SHADOW;
#ifdef __SHADOW_CATCHER__
const uint32_t path_flag = INTEGRATOR_STATE(state, shadow_path, flag);
visibility = SHADOW_CATCHER_PATH_VISIBILITY(path_flag, visibility);
#endif
return visibility;
}
ccl_device bool integrate_intersect_shadow_opaque(KernelGlobals kg,
IntegratorShadowState state,
ccl_private const Ray *ray,
const uint visibility)
{
/* Mask which will pick only opaque visibility bits from the `visibility`.
* Calculate the mask at compile time: the visibility will either be a high bits for the shadow
* catcher objects, or lower bits for the regular objects (there is no need to check the path
* state here again). */
constexpr const uint opaque_mask = SHADOW_CATCHER_VISIBILITY_SHIFT(PATH_RAY_SHADOW_OPAQUE) |
PATH_RAY_SHADOW_OPAQUE;
Intersection isect;
const bool opaque_hit = scene_intersect(kg, ray, visibility & opaque_mask, &isect);
if (!opaque_hit) {
INTEGRATOR_STATE_WRITE(state, shadow_path, num_hits) = 0;
}
return opaque_hit;
}
ccl_device_forceinline int integrate_shadow_max_transparent_hits(KernelGlobals kg,
ConstIntegratorShadowState state)
{
const int transparent_max_bounce = kernel_data.integrator.transparent_max_bounce;
const int transparent_bounce = INTEGRATOR_STATE(state, shadow_path, transparent_bounce);
return max(transparent_max_bounce - transparent_bounce - 1, 0);
}
#ifdef __TRANSPARENT_SHADOWS__
# if defined(__KERNEL_CPU__)
ccl_device int shadow_intersections_compare(const void *a, const void *b)
{
const Intersection *isect_a = (const Intersection *)a;
const Intersection *isect_b = (const Intersection *)b;
if (isect_a->t < isect_b->t)
return -1;
else if (isect_a->t > isect_b->t)
return 1;
else
return 0;
}
# endif
ccl_device_inline void sort_shadow_intersections(IntegratorShadowState state, uint num_hits)
{
kernel_assert(num_hits > 0);
# ifdef __KERNEL_GPU__
/* Use bubble sort which has more friendly memory pattern on GPU. */
bool swapped;
do {
swapped = false;
for (int j = 0; j < num_hits - 1; ++j) {
if (INTEGRATOR_STATE_ARRAY(state, shadow_isect, j, t) >
INTEGRATOR_STATE_ARRAY(state, shadow_isect, j + 1, t)) {
struct Intersection tmp_j ccl_optional_struct_init;
struct Intersection tmp_j_1 ccl_optional_struct_init;
integrator_state_read_shadow_isect(state, &tmp_j, j);
integrator_state_read_shadow_isect(state, &tmp_j_1, j + 1);
integrator_state_write_shadow_isect(state, &tmp_j_1, j);
integrator_state_write_shadow_isect(state, &tmp_j, j + 1);
swapped = true;
}
}
--num_hits;
} while (swapped);
# else
Intersection *isect_array = (Intersection *)state->shadow_isect;
qsort(isect_array, num_hits, sizeof(Intersection), shadow_intersections_compare);
# endif
}
ccl_device bool integrate_intersect_shadow_transparent(KernelGlobals kg,
IntegratorShadowState state,
ccl_private const Ray *ray,
const uint visibility)
{
/* Limit the number hits to the max transparent bounces allowed and the size that we
* have available in the integrator state. */
const uint max_hits = integrate_shadow_max_transparent_hits(kg, state);
uint num_hits = 0;
float throughput = 1.0f;
bool opaque_hit = scene_intersect_shadow_all(
kg, state, ray, visibility, max_hits, &num_hits, &throughput);
/* Computed throughput from baked shadow transparency, where we can bypass recording
* intersections and shader evaluation. */
if (throughput != 1.0f) {
INTEGRATOR_STATE_WRITE(state, shadow_path, throughput) *= throughput;
}
/* If number of hits exceed the transparent bounces limit, make opaque. */
if (num_hits > max_hits) {
opaque_hit = true;
}
if (!opaque_hit) {
const uint num_recorded_hits = min(num_hits, min(max_hits, INTEGRATOR_SHADOW_ISECT_SIZE));
if (num_recorded_hits > 0) {
sort_shadow_intersections(state, num_recorded_hits);
}
INTEGRATOR_STATE_WRITE(state, shadow_path, num_hits) = num_hits;
}
else {
INTEGRATOR_STATE_WRITE(state, shadow_path, num_hits) = 0;
}
return opaque_hit;
}
#endif
ccl_device void integrator_intersect_shadow(KernelGlobals kg, IntegratorShadowState state)
{
PROFILING_INIT(kg, PROFILING_INTERSECT_SHADOW);
/* Read ray from integrator state into local memory. */
Ray ray ccl_optional_struct_init;
integrator_state_read_shadow_ray(kg, state, &ray);
ray.self.object = INTEGRATOR_STATE_ARRAY(state, shadow_isect, 0, object);
ray.self.prim = INTEGRATOR_STATE_ARRAY(state, shadow_isect, 0, prim);
ray.self.light_object = INTEGRATOR_STATE_ARRAY(state, shadow_isect, 1, object);
ray.self.light_prim = INTEGRATOR_STATE_ARRAY(state, shadow_isect, 1, prim);
/* Compute visibility. */
const uint visibility = integrate_intersect_shadow_visibility(kg, state);
#ifdef __TRANSPARENT_SHADOWS__
/* TODO: compile different kernels depending on this? Especially for OptiX
* conditional trace calls are bad. */
const bool opaque_hit = (kernel_data.integrator.transparent_shadows) ?
integrate_intersect_shadow_transparent(kg, state, &ray, visibility) :
integrate_intersect_shadow_opaque(kg, state, &ray, visibility);
#else
const bool opaque_hit = integrate_intersect_shadow_opaque(kg, state, &ray, visibility);
#endif
if (opaque_hit) {
/* Hit an opaque surface, shadow path ends here. */
INTEGRATOR_SHADOW_PATH_TERMINATE(DEVICE_KERNEL_INTEGRATOR_INTERSECT_SHADOW);
return;
}
else {
/* Hit nothing or transparent surfaces, continue to shadow kernel
* for shading and render buffer output.
*
* TODO: could also write to render buffer directly if no transparent shadows?
* Could save a kernel execution for the common case. */
INTEGRATOR_SHADOW_PATH_NEXT(DEVICE_KERNEL_INTEGRATOR_INTERSECT_SHADOW,
DEVICE_KERNEL_INTEGRATOR_SHADE_SHADOW);
return;
}
}
CCL_NAMESPACE_END
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