diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_volume.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_volume.h | 76 |
1 files changed, 53 insertions, 23 deletions
diff --git a/intern/cycles/kernel/kernel_volume.h b/intern/cycles/kernel/kernel_volume.h index cc4b2e3edf1..ea02ede10cd 100644 --- a/intern/cycles/kernel/kernel_volume.h +++ b/intern/cycles/kernel/kernel_volume.h @@ -176,6 +176,8 @@ ccl_device void kernel_volume_shadow_heterogeneous(KernelGlobals *kg, PathState /* compute extinction at the start */ float t = 0.0f; + float3 sum = make_float3(0.0f, 0.0f, 0.0f); + for(int i = 0; i < max_steps; i++) { /* advance to new position */ float new_t = min(ray->t, (i+1) * step); @@ -190,20 +192,26 @@ ccl_device void kernel_volume_shadow_heterogeneous(KernelGlobals *kg, PathState /* compute attenuation over segment */ if(volume_shader_extinction_sample(kg, sd, state, new_P, &sigma_t)) { - /* todo: we could avoid computing expf() for each step by summing, - * because exp(a)*exp(b) = exp(a+b), but we still want a quick - * tp_eps check too */ - tp *= volume_color_transmittance(sigma_t, new_t - t); - - /* stop if nearly all light blocked */ - if(tp.x < tp_eps && tp.y < tp_eps && tp.z < tp_eps) - break; + /* Compute expf() only for every Nth step, to save some calculations + * because exp(a)*exp(b) = exp(a+b), also do a quick tp_eps check then. */ + + sum += (-sigma_t * (new_t - t)); + if((i & 0x07) == 0) { /* ToDo: Other interval? */ + tp = *throughput * make_float3(expf(sum.x), expf(sum.y), expf(sum.z)); + + /* stop if nearly all light is blocked */ + if(tp.x < tp_eps && tp.y < tp_eps && tp.z < tp_eps) + break; + } } /* stop if at the end of the volume */ t = new_t; - if(t == ray->t) + if(t == ray->t) { + /* Update throughput in case we haven't done it above */ + tp = *throughput * make_float3(expf(sum.x), expf(sum.y), expf(sum.z)); break; + } } *throughput = tp; @@ -326,6 +334,7 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_homogeneous(KernelGloba float t = ray->t; float3 new_tp; +#ifdef __VOLUME_SCATTER__ /* randomly scatter, and if we do t is shortened */ if(closure_flag & SD_SCATTER) { /* extinction coefficient */ @@ -379,7 +388,9 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_homogeneous(KernelGloba new_tp = *throughput * transmittance / pdf; } } - else if(closure_flag & SD_ABSORPTION) { + else +#endif + if(closure_flag & SD_ABSORPTION) { /* absorption only, no sampling needed */ float3 transmittance = volume_color_transmittance(coeff.sigma_a, t); new_tp = *throughput * transmittance; @@ -456,6 +467,7 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_heterogeneous_distance( bool scatter = false; /* distance sampling */ +#ifdef __VOLUME_SCATTER__ if((closure_flag & SD_SCATTER) || (has_scatter && (closure_flag & SD_ABSORPTION))) { has_scatter = true; @@ -491,7 +503,9 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_heterogeneous_distance( xi = 1.0f - (1.0f - xi)/sample_transmittance; } } - else if(closure_flag & SD_ABSORPTION) { + else +#endif + if(closure_flag & SD_ABSORPTION) { /* absorption only, no sampling needed */ float3 sigma_a = coeff.sigma_a; @@ -546,13 +560,12 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_heterogeneous_distance( * between the endpoints. distance sampling is used to decide if we will * scatter or not. */ ccl_device_noinline VolumeIntegrateResult kernel_volume_integrate(KernelGlobals *kg, - PathState *state, ShaderData *sd, Ray *ray, PathRadiance *L, float3 *throughput, RNG *rng) + PathState *state, ShaderData *sd, Ray *ray, PathRadiance *L, float3 *throughput, RNG *rng, bool heterogeneous) { /* 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); - bool heterogeneous = volume_stack_is_heterogeneous(kg, state->volume_stack); shader_setup_from_volume(kg, sd, ray, state->bounce, state->transparent_bounce); @@ -724,16 +737,15 @@ ccl_device void kernel_volume_decoupled_free(KernelGlobals *kg, VolumeSegment *s * scattering, they always scatter if there is any non-zero scattering * coefficient. * - * these also do not do emission or modify throughput. */ + * these also do not do emission or modify throughput. + * + * function is expected to return VOLUME_PATH_SCATTERED when probalistic_scatter is false */ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter( KernelGlobals *kg, PathState *state, Ray *ray, ShaderData *sd, float3 *throughput, float rphase, float rscatter, const VolumeSegment *segment, const float3 *light_P, bool probalistic_scatter) { - int closure_flag = segment->closure_flag; - - if(!(closure_flag & SD_SCATTER)) - return VOLUME_PATH_MISSED; + kernel_assert(segment->closure_flag & SD_SCATTER); /* pick random color channel, we use the Veach one-sample * model with balance heuristic for the channels */ @@ -845,15 +857,33 @@ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter( float3 step_pdf_distance = make_float3(1.0f, 1.0f, 1.0f); if(segment->numsteps > 1) { - /* todo: optimize using binary search */ float3 prev_cdf_distance = make_float3(0.0f, 0.0f, 0.0f); - for(int i = 0; i < segment->numsteps-1; i++, step++) { - if(sample_t < step->t) + int numsteps = segment->numsteps; + int high = numsteps - 1; + int low = 0; + int mid; + + while(low < high) { + mid = (low + high) >> 1; + + if(sample_t < step[mid].t) + high = mid; + else if(sample_t >= step[mid + 1].t) + low = mid + 1; + else { + /* found our interval in step[mid] .. step[mid+1] */ + prev_t = step[mid].t; + prev_cdf_distance = step[mid].cdf_distance; + step += mid+1; break; + } + } - prev_t = step->t; - prev_cdf_distance = step->cdf_distance; + if(low >= numsteps - 1) { + prev_t = step[numsteps - 1].t; + prev_cdf_distance = step[numsteps-1].cdf_distance; + step += numsteps - 1; } /* pdf for picking step with distance sampling */ |