[Bf-blender-cvs] [1e43f0d] master: Cycles: Set of fixes for delayed SSS ray tracing
Sergey Sharybin
noreply at git.blender.org
Sat Nov 28 16:13:15 CET 2015
Commit: 1e43f0d74216cc936e6a708be321ba2c05b66ca1
Author: Sergey Sharybin
Date: Sat Nov 28 19:30:35 2015 +0500
Branches: master
https://developer.blender.org/rB1e43f0d74216cc936e6a708be321ba2c05b66ca1
Cycles: Set of fixes for delayed SSS ray tracing
There were multiple issues which are solved now:
- It was possible that ray wouldn't be bounced off the BSSRDF, for example
when PDF or shader eval is zero. In this case PathState might have been
left in pre-bounced state which would have been gave incorrect shading
results.
This is solved by having separate PathState for each of the hits.
- Path radiance summing wasn't happening correct as well, indirect rays
were using wrong path radiance in the case when there were more than
one hit recorded.
This is now using a bit trickier state machine which calculates path
radiance for just SSS (both direct and indirect) and then sums it back
to the final radiance.
- Previous commit wasn't totally correct either and was an induced bug
due to wrong path state left from the "un-happened" ray bounce.
There should be no special case happening here, BSSRDFs will be replaced
with diffuse ones due to PATH_RAY_DIFFUSE_ANCESTOR flag.
- Merged back codebases for "delayed" and "immediate" indirect SSS ray
tracing, hopefully making it easier to maintain the codebase.
Sure this changes brings memory usage back by about 4-5%, but overall
it's still about 2x memory reduction for the experimental kernel here.
Thanks Brecht for the review!
===================================================================
M intern/cycles/kernel/kernel_bake.h
M intern/cycles/kernel/kernel_path.h
M intern/cycles/kernel/kernel_types.h
===================================================================
diff --git a/intern/cycles/kernel/kernel_bake.h b/intern/cycles/kernel/kernel_bake.h
index 57cbf0b6..a04e759 100644
--- a/intern/cycles/kernel/kernel_bake.h
+++ b/intern/cycles/kernel/kernel_bake.h
@@ -65,6 +65,7 @@ ccl_device void compute_light_pass(KernelGlobals *kg, ShaderData *sd, PathRadian
if((is_combined || is_sss_sample) && (sd->flag & SD_BSSRDF)) {
/* when mixing BSSRDF and BSDF closures we should skip BSDF lighting if scattering was successful */
SubsurfaceIndirectRays ss_indirect;
+ ss_indirect.tracing = false;
ss_indirect.num_rays = 0;
if(kernel_path_subsurface_scatter(kg,
sd,
@@ -75,14 +76,13 @@ ccl_device void compute_light_pass(KernelGlobals *kg, ShaderData *sd, PathRadian
&throughput,
&ss_indirect))
{
-# ifdef __SUBSURFACE_DELAYED_INDIRECT__
while(ss_indirect.num_rays) {
kernel_path_subsurface_setup_indirect(kg,
&ss_indirect,
- &L_sample,
- &state,
&ray,
+ &state,
&ray,
+ &L_sample,
&throughput);
kernel_path_indirect(kg,
&rng,
@@ -91,8 +91,8 @@ ccl_device void compute_light_pass(KernelGlobals *kg, ShaderData *sd, PathRadian
state.num_samples,
&state,
&L_sample);
+ kernel_path_subsurface_accum_indirect(&ss_indirect, &L_sample);
}
-# endif /* __SUBSURFACE_DELAYED_INDIRECT__ */
is_sss_sample = true;
}
}
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 850bfb2..721e0fc 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -448,21 +448,13 @@ ccl_device bool kernel_path_subsurface_scatter(
/* do bssrdf scatter step if we picked a bssrdf closure */
if(sc) {
- uint lcg_state = lcg_state_init(rng, state, 0x68bc21eb);
+ /* We should never have two consecutive BSSRDF bounces,
+ * the second one should be converted to a diffuse BSDF to
+ * avoid this.
+ */
+ kernel_assert(!ss_indirect->tracing);
- /* If indirect ray hits BSSRDF we replace it with diffuse BSDF. */
- if(ss_indirect->num_rays) {
- float bssrdf_u, bssrdf_v;
- path_state_rng_2D(kg, rng, state, PRNG_BSDF_U, &bssrdf_u, &bssrdf_v);
- subsurface_scatter_step(kg,
- sd,
- state->flag,
- sc,
- &lcg_state,
- bssrdf_u, bssrdf_v,
- false);
- return false;
- }
+ uint lcg_state = lcg_state_init(rng, state, 0x68bc21eb);
SubsurfaceIntersection ss_isect;
float bssrdf_u, bssrdf_v;
@@ -493,9 +485,10 @@ ccl_device bool kernel_path_subsurface_scatter(
sc,
false);
- PathState *hit_state = &ss_indirect->state;
+ PathState *hit_state = &ss_indirect->state[ss_indirect->num_rays];
Ray *hit_ray = &ss_indirect->rays[ss_indirect->num_rays];
float3 *hit_tp = &ss_indirect->throughputs[ss_indirect->num_rays];
+ PathRadiance *hit_L = &ss_indirect->L[ss_indirect->num_rays];
*hit_state = *state;
*hit_ray = *ray;
@@ -503,51 +496,25 @@ ccl_device bool kernel_path_subsurface_scatter(
hit_state->rng_offset += PRNG_BOUNCE_NUM;
- kernel_path_surface_connect_light(kg, rng, sd, *hit_tp, state, L);
+ path_radiance_init(hit_L, kernel_data.film.use_light_pass);
+ kernel_path_surface_connect_light(kg, rng, sd, *hit_tp, state, hit_L);
if(kernel_path_surface_bounce(kg,
rng,
sd,
hit_tp,
hit_state,
- L,
+ hit_L,
hit_ray))
{
#ifdef __LAMP_MIS__
hit_state->ray_t = 0.0f;
#endif
-#ifdef __SUBSURFACE_DELAYED_INDIRECT__
ss_indirect->num_rays++;
-#else
-# ifdef __VOLUME__
- if(ss_indirect->need_update_volume_stack) {
- Ray volume_ray = *ray;
-
- /* Setup ray from previous surface point to the new one. */
- volume_ray.D = normalize_len(hit_ray->P - volume_ray.P,
- &volume_ray.t);
-
- kernel_volume_stack_update_for_subsurface(kg,
- &volume_ray,
- hit_state->volume_stack);
- }
-# endif /* __VOLUME__ */
-
- kernel_path_indirect(kg,
- rng,
- hit_ray,
- *hit_tp,
- hit_state->num_samples,
- hit_state,
- 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);
-#endif
+ }
+ else {
+ path_radiance_accum_sample(L, hit_L, 1);
}
}
return true;
@@ -555,23 +522,38 @@ ccl_device bool kernel_path_subsurface_scatter(
return false;
}
-#ifdef __SUBSURFACE_DELAYED_INDIRECT__
+ccl_device void kernel_path_subsurface_accum_indirect(
+ SubsurfaceIndirectRays *ss_indirect,
+ PathRadiance *L)
+{
+ if(ss_indirect->tracing) {
+ path_radiance_sum_indirect(L);
+ path_radiance_accum_sample(&ss_indirect->direct_L, L, 1);
+ if(ss_indirect->num_rays == 0) {
+ *L = ss_indirect->direct_L;
+ }
+ }
+}
+
ccl_device void kernel_path_subsurface_setup_indirect(
KernelGlobals *kg,
SubsurfaceIndirectRays *ss_indirect,
- PathRadiance *L,
+ const Ray *orig_ray,
PathState *state,
- Ray *orig_ray,
Ray *ray,
+ PathRadiance *L,
float3 *throughput)
{
+ if(!ss_indirect->tracing) {
+ ss_indirect->direct_L = *L;
+ }
+ ss_indirect->tracing = true;
+
/* Setup state, ray and throughput for indirect SSS rays. */
ss_indirect->num_rays--;
Ray *indirect_ray = &ss_indirect->rays[ss_indirect->num_rays];
-
- *state = ss_indirect->state;
- *throughput = ss_indirect->throughputs[ss_indirect->num_rays];
+ PathRadiance *indirect_L = &ss_indirect->L[ss_indirect->num_rays];
#ifdef __VOLUME__
if(ss_indirect->need_update_volume_stack) {
@@ -587,17 +569,15 @@ ccl_device void kernel_path_subsurface_setup_indirect(
}
#endif /* __VOLUME__ */
+ *state = ss_indirect->state[ss_indirect->num_rays];
*ray = *indirect_ray;
+ *L = *indirect_L;
+ *throughput = ss_indirect->throughputs[ss_indirect->num_rays];
- /* For render passes, sum and reset indirect light pass variables
- * for the next samples.
- */
- path_radiance_sum_indirect(L);
- path_radiance_reset_indirect(L);
+ state->rng_offset += ss_indirect->num_rays * PRNG_BOUNCE_NUM;
}
-#endif /* __SUBSURFACE_DELAYED_INDIRECT__ */
-#endif
+#endif /* __SUBSURFACE__ */
ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample, Ray ray, ccl_global float *buffer)
{
@@ -618,9 +598,9 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
#ifdef __SUBSURFACE__
SubsurfaceIndirectRays ss_indirect;
+ ss_indirect.tracing = false;
ss_indirect.num_rays = 0;
-# ifdef __SUBSURFACE_DELAYED_INDIRECT__
/* TODO(sergey): Avoid having explicit copy of the pre-subsurface scatter
* ray by storing an updated version of state in the ss_indirect which will
* be updated to the new volume stack.
@@ -628,7 +608,6 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
Ray ss_orig_ray;
for(;;) {
-# endif /* __SUBSURFACE_DELAYED_INDIRECT__ */
#endif
/* path iteration */
@@ -877,9 +856,7 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
&throughput,
&ss_indirect))
{
-# ifdef __SUBSURFACE_DELAYED_INDIRECT__
ss_orig_ray = ray;
-# endif /* __SUBSURFACE_DELAYED_INDIRECT__ */
break;
}
}
@@ -893,24 +870,26 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
break;
}
-#ifdef __SUBSURFACE_DELAYED_INDIRECT__
+#ifdef __SUBSURFACE__
+ kernel_path_subsurface_accum_indirect(&ss_indirect, &L);
+
/* Trace indirect subsurface rays by restarting the loop. this uses less
* stack memory than invoking kernel_path_indirect.
*/
if(ss_indirect.num_rays) {
kernel_path_subsurface_setup_indirect(kg,
&ss_indirect,
- &L,
- &state,
&ss_orig_ray,
+ &state,
&ray,
+ &L,
&throughput);
}
else {
break;
}
}
-#endif /* __SUBSURFACE_DELAYED_INDIRECT__ */
+#endif /* __SUBSURFACE__ */
float3 L_sum = path_radiance_clamp_and_sum(kg, &L);
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index b986988..017126d 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -87,7 +87,6 @@ CCL_NAMESPACE_BEGIN
/* Experimental on GPU */
#ifdef __KERNEL_EXPERIMENTAL__
#define __SUBSURFACE__
-#define __SUBSURFACE_DELAYED_INDIRECT__
#define __CMJ__
#endif
@@ -770,11 +769,14 @@ struct SubsurfaceIntersection
struct SubsurfaceIndirectRays
{
bool need_update_volume_stack;
- PathState state;
+ bool tracing;
+ PathState state[BSSRDF_MAX_HITS];
+ PathRadiance direct_L;
int num_rays;
Ray rays[BSSRDF_MAX_HITS];
float3 throughputs[BSSRDF_MAX_HITS];
+ PathRadiance L[BSSRDF_MAX_HITS];
};
/* Constant Kernel Dat
@@ Diff output truncated at 10240 characters. @@
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