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/*
* Copyright 2011-2013 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
*/
CCL_NAMESPACE_BEGIN
ccl_device_inline bool shadow_blocked(KernelGlobals *kg, PathState *state, Ray *ray, float3 *shadow)
{
*shadow = make_float3(1.0f, 1.0f, 1.0f);
if(ray->t == 0.0f)
return false;
Intersection isect;
#ifdef __HAIR__
bool result = scene_intersect(kg, ray, PATH_RAY_SHADOW_OPAQUE, &isect, NULL, 0.0f, 0.0f);
#else
bool result = scene_intersect(kg, ray, PATH_RAY_SHADOW_OPAQUE, &isect);
#endif
#ifdef __TRANSPARENT_SHADOWS__
if(result && kernel_data.integrator.transparent_shadows) {
/* transparent shadows work in such a way to try to minimize overhead
* in cases where we don't need them. after a regular shadow ray is
* cast we check if the hit primitive was potentially transparent, and
* only in that case start marching. this gives on extra ray cast for
* the cases were we do want transparency.
*
* also note that for this to work correct, multi close sampling must
* be used, since we don't pass a random number to shader_eval_surface */
if(shader_transparent_shadow(kg, &isect)) {
float3 throughput = make_float3(1.0f, 1.0f, 1.0f);
float3 Pend = ray->P + ray->D*ray->t;
int bounce = state->transparent_bounce;
#ifdef __VOLUME__
PathState ps = *state;
#endif
for(;;) {
if(bounce >= kernel_data.integrator.transparent_max_bounce) {
return true;
}
else if(bounce >= kernel_data.integrator.transparent_min_bounce) {
/* todo: get random number somewhere for probabilistic terminate */
#if 0
float probability = average(throughput);
float terminate = 0.0f;
if(terminate >= probability)
return true;
throughput /= probability;
#endif
}
#ifdef __HAIR__
if(!scene_intersect(kg, ray, PATH_RAY_SHADOW_TRANSPARENT, &isect, NULL, 0.0f, 0.0f)) {
#else
if(!scene_intersect(kg, ray, PATH_RAY_SHADOW_TRANSPARENT, &isect)) {
#endif
#ifdef __VOLUME__
/* attenuation for last line segment towards light */
if(ps.volume_stack[0].shader != SHADER_NONE)
kernel_volume_shadow(kg, &ps, ray, &throughput);
#endif
*shadow *= throughput;
return false;
}
if(!shader_transparent_shadow(kg, &isect))
return true;
#ifdef __VOLUME__
/* attenuation between last surface and next surface */
if(ps.volume_stack[0].shader != SHADER_NONE) {
Ray segment_ray = *ray;
segment_ray.t = isect.t;
kernel_volume_shadow(kg, &ps, &segment_ray, &throughput);
}
#endif
/* setup shader data at surface */
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, ray, state->bounce+1);
/* attenuation from transparent surface */
if(!(sd.flag & SD_HAS_ONLY_VOLUME)) {
shader_eval_surface(kg, &sd, 0.0f, PATH_RAY_SHADOW, SHADER_CONTEXT_SHADOW);
throughput *= shader_bsdf_transparency(kg, &sd);
}
/* move ray forward */
ray->P = ray_offset(sd.P, -sd.Ng);
if(ray->t != FLT_MAX)
ray->D = normalize_len(Pend - ray->P, &ray->t);
#ifdef __VOLUME__
/* exit/enter volume */
kernel_volume_stack_enter_exit(kg, &sd, ps.volume_stack);
#endif
bounce++;
}
}
}
#ifdef __VOLUME__
else if(!result && state->volume_stack[0].shader != SHADER_NONE) {
/* apply attenuation from current volume shader */
kernel_volume_shadow(kg, state, ray, shadow);
}
#endif
#endif
return result;
}
CCL_NAMESPACE_END
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