[Bf-blender-cvs] [967ccd1dd7e] cycles-x: Cycles X: add equiangular volume sampling for direct light
Brecht Van Lommel
noreply at git.blender.org
Fri Jul 23 19:29:02 CEST 2021
Commit: 967ccd1dd7ee44824b54bb35074b27811103a739
Author: Brecht Van Lommel
Date: Wed Jul 7 18:33:22 2021 +0200
Branches: cycles-x
https://developer.blender.org/rB967ccd1dd7ee44824b54bb35074b27811103a739
Cycles X: add equiangular volume sampling for direct light
Indirect always uses distance sampling.
Ref D11845
===================================================================
M intern/cycles/blender/addon/ui.py
M intern/cycles/kernel/integrator/integrator_shade_volume.h
===================================================================
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 5b515aa98e3..8553d172ccf 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1449,8 +1449,7 @@ class CYCLES_WORLD_PT_settings_volume(CyclesButtonsPanel, Panel):
col = layout.column()
sub = col.column()
- sub.active = use_cpu(context)
- sub.prop(cworld, "volume_sampling", text="Sampling")
+ col.prop(cworld, "volume_sampling", text="Sampling")
col.prop(cworld, "volume_interpolation", text="Interpolation")
col.prop(cworld, "homogeneous_volume", text="Homogeneous")
sub = col.column()
@@ -1589,8 +1588,7 @@ class CYCLES_MATERIAL_PT_settings_volume(CyclesButtonsPanel, Panel):
col = layout.column()
sub = col.column()
- sub.active = use_cpu(context)
- sub.prop(cmat, "volume_sampling", text="Sampling")
+ col.prop(cmat, "volume_sampling", text="Sampling")
col.prop(cmat, "volume_interpolation", text="Interpolation")
col.prop(cmat, "homogeneous_volume", text="Homogeneous")
sub = col.column()
diff --git a/intern/cycles/kernel/integrator/integrator_shade_volume.h b/intern/cycles/kernel/integrator/integrator_shade_volume.h
index 4e4b6243615..1482b0b5c4d 100644
--- a/intern/cycles/kernel/integrator/integrator_shade_volume.h
+++ b/intern/cycles/kernel/integrator/integrator_shade_volume.h
@@ -33,7 +33,6 @@ typedef enum VolumeIntegrateEvent {
typedef struct VolumeIntegrateResult {
/* Throughput and offset for direct light scattering. */
- VolumeSampleMethod direct_sample_method;
bool direct_scatter;
float3 direct_throughput;
float direct_t;
@@ -388,9 +387,6 @@ typedef struct VolumeIntegrateState {
float start_t;
float end_t;
- /* Current throughput. */
- float3 throughput;
-
/* If volume is absorption-only up to this point, and no probabilistic
* scattering or termination has been used yet. */
bool absorption_only;
@@ -398,6 +394,9 @@ typedef struct VolumeIntegrateState {
/* Random numbers for scattering. */
float rscatter;
float rphase;
+
+ /* Sampling. */
+ VolumeSampleMethod direct_sample_method;
} VolumeIntegrateState;
ccl_device_forceinline void volume_integrate_step_scattering(
@@ -407,46 +406,66 @@ ccl_device_forceinline void volume_integrate_step_scattering(
VolumeIntegrateState &ccl_restrict vstate,
VolumeIntegrateResult &ccl_restrict result)
{
- /* Distance sampling */
-
- /* Pick random color channel, we use the Veach one-sample
- * model with balance heuristic for the channels. */
- const float3 albedo = safe_divide_color(coeff.sigma_s, coeff.sigma_t);
- float3 channel_pdf;
- const int channel = volume_sample_channel(
- albedo, result.indirect_throughput, vstate.rphase, &channel_pdf);
-
- /* decide if we will scatter or continue */
- const float sample_transmittance = volume_channel_get(transmittance, channel);
-
- if (1.0f - vstate.rscatter >= sample_transmittance) {
- /* compute sampling distance */
- const float sample_sigma_t = volume_channel_get(coeff.sigma_t, channel);
- const float new_dt = -logf(1.0f - vstate.rscatter) / sample_sigma_t;
- const float new_t = vstate.start_t + new_dt;
-
- /* transmittance and pdf */
- const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);
- const float3 pdf = coeff.sigma_t * new_transmittance;
-
- /* throughput */
- result.indirect_scatter = true;
- result.indirect_t = new_t;
- result.indirect_throughput *= coeff.sigma_s * new_transmittance / dot(channel_pdf, pdf);
- shader_copy_volume_phases(&result.indirect_phases, sd);
-
- result.direct_scatter = true;
- result.direct_t = result.indirect_t;
- result.direct_throughput = result.indirect_throughput;
- shader_copy_volume_phases(&result.direct_phases, sd); /* TODO: only copy once? */
+ /* Equiangular sampling for direct lighting. */
+ if (vstate.direct_sample_method == VOLUME_SAMPLE_EQUIANGULAR && !result.direct_scatter) {
+ if (result.direct_t >= vstate.start_t && result.direct_t <= vstate.end_t) {
+ const float new_dt = result.direct_t - vstate.start_t;
+ const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);
+
+ result.direct_scatter = true;
+ result.direct_throughput *= coeff.sigma_s * new_transmittance;
+ shader_copy_volume_phases(&result.direct_phases, sd);
+ }
+ else {
+ result.direct_throughput *= transmittance;
+ }
}
- else {
- /* throughput */
- const float pdf = dot(channel_pdf, transmittance);
- result.indirect_throughput *= transmittance / pdf;
- /* remap rscatter so we can reuse it and keep thing stratified */
- vstate.rscatter = 1.0f - (1.0f - vstate.rscatter) / sample_transmittance;
+ /* Distance sampling for indirect and optional direct lighting. */
+ if (!result.indirect_scatter) {
+ /* Pick random color channel, we use the Veach one-sample
+ * model with balance heuristic for the channels. */
+ const float3 albedo = safe_divide_color(coeff.sigma_s, coeff.sigma_t);
+ float3 channel_pdf;
+ const int channel = volume_sample_channel(
+ albedo, result.indirect_throughput, vstate.rphase, &channel_pdf);
+
+ /* decide if we will scatter or continue */
+ const float sample_transmittance = volume_channel_get(transmittance, channel);
+
+ if (1.0f - vstate.rscatter >= sample_transmittance) {
+ /* compute sampling distance */
+ const float sample_sigma_t = volume_channel_get(coeff.sigma_t, channel);
+ const float new_dt = -logf(1.0f - vstate.rscatter) / sample_sigma_t;
+ const float new_t = vstate.start_t + new_dt;
+
+ /* transmittance and pdf */
+ const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);
+ const float distance_pdf = dot(channel_pdf, coeff.sigma_t * new_transmittance);
+
+ /* throughput */
+ result.indirect_scatter = true;
+ result.indirect_t = new_t;
+ result.indirect_throughput *= coeff.sigma_s * new_transmittance / distance_pdf;
+ shader_copy_volume_phases(&result.indirect_phases, sd);
+
+ if (vstate.direct_sample_method != VOLUME_SAMPLE_EQUIANGULAR) {
+ /* If using distance sampling for direct light, just copy parameters
+ * of indirect light since we scatter at the same point then. */
+ result.direct_scatter = true;
+ result.direct_t = result.indirect_t;
+ result.direct_throughput = result.indirect_throughput;
+ shader_copy_volume_phases(&result.direct_phases, sd);
+ }
+ }
+ else {
+ /* throughput */
+ const float pdf = dot(channel_pdf, transmittance);
+ result.indirect_throughput *= transmittance / pdf;
+
+ /* remap rscatter so we can reuse it and keep thing stratified */
+ vstate.rscatter = 1.0f - (1.0f - vstate.rscatter) / sample_transmittance;
+ }
}
}
@@ -454,14 +473,16 @@ ccl_device_forceinline void volume_integrate_step_scattering(
* volume until we reach the end, get absorbed entirely, or run out of
* iterations. this does probabilistically scatter or get transmitted through
* for path tracing where we don't want to branch. */
-ccl_device_forceinline void volume_integrate_heterogeneous(INTEGRATOR_STATE_ARGS,
- Ray *ccl_restrict ray,
- ShaderData *ccl_restrict sd,
- const RNGState *rng_state,
- ccl_global float *ccl_restrict
- render_buffer,
- const float object_step_size,
- VolumeIntegrateResult &result)
+ccl_device_forceinline void volume_integrate_heterogeneous(
+ INTEGRATOR_STATE_ARGS,
+ Ray *ccl_restrict ray,
+ ShaderData *ccl_restrict sd,
+ const RNGState *rng_state,
+ ccl_global float *ccl_restrict render_buffer,
+ const float object_step_size,
+ const VolumeSampleMethod direct_sample_method,
+ const float3 equiangular_light_P,
+ VolumeIntegrateResult &result)
{
/* Prepare for stepping.
* Using a different step offset for the first step avoids banding artifacts. */
@@ -483,12 +504,21 @@ ccl_device_forceinline void volume_integrate_heterogeneous(INTEGRATOR_STATE_ARGS
vstate.absorption_only = true;
vstate.rscatter = path_state_rng_1D(kg, rng_state, PRNG_SCATTER_DISTANCE);
vstate.rphase = path_state_rng_1D(kg, rng_state, PRNG_PHASE_CHANNEL);
+ vstate.direct_sample_method = direct_sample_method;
/* Initialize volume integration result. */
const float3 throughput = INTEGRATOR_STATE(path, throughput);
result.direct_throughput = throughput;
result.indirect_throughput = throughput;
+ /* Equiangular sampling: compute distance and PDF in advance. */
+ if (vstate.direct_sample_method == VOLUME_SAMPLE_EQUIANGULAR) {
+ float equiangular_pdf;
+ result.direct_t = volume_equiangular_sample(
+ ray, equiangular_light_P, vstate.rscatter, &equiangular_pdf);
+ result.direct_throughput /= equiangular_pdf;
+ }
+
for (int i = 0; i < max_steps; i++) {
/* Advance to new position */
vstate.end_t = min(ray->t, (i + steps_offset) * step_size);
@@ -683,7 +713,7 @@ ccl_device_forceinline void integrate_volume_direct_light(INTEGRATOR_STATE_ARGS,
}
# endif
-/* Path tracing: scatter in new direction using phase function. */
+/* Path tracing: scatter in new direction using phase function */
ccl_device_forceinline bool integrate_volume_phase_scatter(INTEGRATOR_STATE_ARGS,
ShaderData *sd,
const RNGState *rng_state,
@@ -756,23 +786,35 @@ ccl_device VolumeIntegrateEvent volume_integrate(INTEGRATOR_STATE_ARGS,
RNGState rng_state;
path_state_rng_load(INTEGRATOR_STATE_PASS, &rng_state);
- /* Sample light ahead of volume ste
@@ Diff output truncated at 10240 characters. @@
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