Cr8-xyz/blender
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Cycles volume: change heterogeneous volume sampling in branched path first hit.

Browse Source 
This now uses decoupled ray marching, and removes the probalistic scattering.
What this means is that each AA sample will be slower but contain less noise,
hopefully giving less render time to reach the same noise levels.

For those following along, there's still a bunch of volume sampling improvements
to do: all-light sampling, multiple importance sampling, transmittance threshold,
better indirect light handling, multiple scatter approximation.
This commit is contained in:
Brecht Van Lommel
2014-03-29 13:03:50 +01:00
parent 3847d0c0df
commit f449542d6a
2 changed files with 77 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
intern/cycles/kernel/kernel_path.h
View File

@@ -261,7 +261,7 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, Ray ray, ccl_g
ShaderData volume_sd;
VolumeIntegrateResult result = kernel_volume_integrate(kg, &state,
&volume_sd, &volume_ray, L, &throughput, rng, false);
&volume_sd, &volume_ray, L, &throughput, rng);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_integrate_scatter_lighting(kg, rng, &volume_sd, &throughput, &state, L, &ray, 1.0f))
@@ -650,7 +650,7 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
ShaderData volume_sd;
VolumeIntegrateResult result = kernel_volume_integrate(kg, &state,
&volume_sd, &volume_ray, &L, &throughput, rng, false);
&volume_sd, &volume_ray, &L, &throughput, rng);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_integrate_scatter_lighting(kg, rng, &volume_sd, &throughput, &state, &L, &ray, 1.0f))
@@ -1090,6 +1090,60 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
Ray volume_ray = ray;
volume_ray.t = (hit)? isect.t: FLT_MAX;
#ifdef __KERNEL_CPU__
/* decoupled ray marching only supported on CPU */
bool heterogeneous = volume_stack_is_heterogeneous(kg, state.volume_stack);
/* cache steps along volume for repeated sampling */
VolumeSegment volume_segment;
ShaderData volume_sd;
shader_setup_from_volume(kg, &volume_sd, &volume_ray, state.bounce);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_sd, &volume_segment, heterogeneous);
/* sample scattering */
int num_samples = kernel_data.integrator.volume_samples;
float num_samples_inv = 1.0f/num_samples;
for(int j = 0; j < num_samples; j++) {
/* workaround to fix correlation bug in T38710, can find better solution
* in random number generator later, for now this is done here to not impact
* performance of rendering without volumes */
RNG tmp_rng = cmj_hash(*rng, state.rng_offset);
PathState ps = state;
Ray pray = ray;
float3 tp = throughput;
/* branch RNG state */
path_state_branch(&ps, j, num_samples);
VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
&ps, &volume_ray, &volume_sd, &tp, &tmp_rng, &volume_segment);
if(result == VOLUME_PATH_SCATTERED) {
/* todo: use all-light sampling */
if(kernel_path_integrate_scatter_lighting(kg, rng, &volume_sd, &tp, &ps, &L, &pray, num_samples_inv)) {
kernel_path_indirect(kg, rng, pray, buffer, tp*num_samples_inv, num_samples, ps, &L);
/* for render passes, sum and reset indirect light pass variables
* for the next samples */
path_radiance_sum_indirect(&L);
path_radiance_reset_indirect(&L);
}
}
}
/* emission and transmittance */
if(volume_segment.closure_flag & SD_EMISSION)
path_radiance_accum_emission(&L, throughput, volume_segment.accum_emission, state.bounce);
throughput *= volume_segment.accum_transmittance;
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
#else
/* GPU: no decoupled ray marching, scatter probalistically */
int num_samples = kernel_data.integrator.volume_samples;
float num_samples_inv = 1.0f/num_samples;
@@ -1106,7 +1160,7 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
path_state_branch(&ps, j, num_samples);
VolumeIntegrateResult result = kernel_volume_integrate(kg, &ps,
&volume_sd, &volume_ray, &L, &tp, rng, true);
&volume_sd, &volume_ray, &L, &tp, rng);
if(result == VOLUME_PATH_SCATTERED) {
/* todo: use all-light sampling */
@@ -1123,6 +1177,7 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
/* todo: avoid this calculation using decoupled ray marching */
kernel_volume_shadow(kg, &state, &volume_ray, &throughput);
#endif
}
#endif