diff options
author | Brecht Van Lommel <brechtvanlommel@gmail.com> | 2017-09-08 02:42:14 +0300 |
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committer | Brecht Van Lommel <brechtvanlommel@gmail.com> | 2017-09-12 13:45:29 +0300 |
commit | cd6c9e9e5f4726ab0b0b2c58249f98dab5c5d267 (patch) | |
tree | c40d2b865394ed4cfe3b4da23e650c783d4578de /intern/cycles/kernel/kernel_path_surface.h | |
parent | d454a44e96649103772ae2c8707ee1ef5e46080c (diff) |
Cycles: improve sample stratification on area lights for path tracing.
Previously we used a 1D sequence to select a light, and another 2D sequence
to sample a point on the light. For multiple lights this meant each light
would get a random subset of a 2D stratified sequence, which is not
guaranteed to be stratified anymore.
Now we use only a 2D sequence, split into segments along the X axis, one for
each light. The samples that fall within a segment then each are a stratified
sequence, at least in the limit. So for example for two lights, we split up
the unit square into two segments [0,0.5[ x [0,1[ and [0.5,1[ x [0,1[.
This doesn't make much difference in most scenes, mainly helps if you have a
few large area lights or some types of HDR backgrounds.
Diffstat (limited to 'intern/cycles/kernel/kernel_path_surface.h')
-rw-r--r-- | intern/cycles/kernel/kernel_path_surface.h | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/intern/cycles/kernel/kernel_path_surface.h b/intern/cycles/kernel/kernel_path_surface.h index 6c3a444e48a..e798fcc6a2c 100644 --- a/intern/cycles/kernel/kernel_path_surface.h +++ b/intern/cycles/kernel/kernel_path_surface.h @@ -85,17 +85,16 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light( float num_samples_inv = num_samples_adjust/num_samples; for(int j = 0; j < num_samples; j++) { - float light_t = path_branched_rng_1D(kg, state->rng_hash, state, j, num_samples, PRNG_LIGHT); float light_u, light_v; path_branched_rng_2D(kg, state->rng_hash, state, j, num_samples, PRNG_LIGHT_U, &light_u, &light_v); float terminate = path_branched_rng_light_termination(kg, state->rng_hash, state, j, num_samples); /* only sample triangle lights */ if(kernel_data.integrator.num_all_lights) - light_t = 0.5f*light_t; + light_u = 0.5f*light_u; LightSample ls; - if(light_sample(kg, light_t, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { + if(light_sample(kg, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { /* Same as above, probability needs to be corrected since the sampling was forced to select a mesh light. */ if(kernel_data.integrator.num_all_lights) ls.pdf *= 2.0f; @@ -118,13 +117,12 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light( } else { /* sample one light at random */ - float light_t = path_state_rng_1D(kg, state, PRNG_LIGHT); float light_u, light_v; path_state_rng_2D(kg, state, PRNG_LIGHT_U, &light_u, &light_v); float terminate = path_state_rng_light_termination(kg, state); LightSample ls; - if(light_sample(kg, light_t, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { + if(light_sample(kg, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { /* sample random light */ if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) { /* trace shadow ray */ @@ -238,7 +236,6 @@ ccl_device_inline void kernel_path_surface_connect_light(KernelGlobals *kg, #endif /* sample illumination from lights to find path contribution */ - float light_t = path_state_rng_1D(kg, state, PRNG_LIGHT); float light_u, light_v; path_state_rng_2D(kg, state, PRNG_LIGHT_U, &light_u, &light_v); @@ -251,7 +248,7 @@ ccl_device_inline void kernel_path_surface_connect_light(KernelGlobals *kg, #endif LightSample ls; - if(light_sample(kg, light_t, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { + if(light_sample(kg, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) { float terminate = path_state_rng_light_termination(kg, state); if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) { /* trace shadow ray */ |