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Cycles: multiple importance sampling for lamps, which helps reduce noise for

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big lamps and sharp glossy reflections. This was already supported for mesh
lights and the background, so lamps should do it too.

This is not for free and it's a bit slower than I hoped even though there is
no extra BVH ray intersection. I'll try to optimize it more later.

* Area lights look a bit different now, they had the wrong shape before.
* Also fixes a sampling issue in the non-progressive integrator.
* Only enabled for the CPU, will test on the GPU later.
* An option to disable this will be added for situations where it does not help.

Same time comparison before/after:
http://www.pasteall.org/pic/show.php?id=43313
http://www.pasteall.org/pic/show.php?id=43314
This commit is contained in:
Brecht Van Lommel
2013-01-09 21:09:20 +00:00
parent 97d1abfe95
commit ad10cbf04a
10 changed files with 586 additions and 200 deletions
Download Patch File Download Diff File Expand all files Collapse all files

78
intern/cycles/kernel/kernel_path.h
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@@ -238,6 +238,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
float min_ray_pdf = FLT_MAX;
float ray_pdf = 0.0f;
float ray_t = 0.0f;
PathState state;
int rng_offset = PRNG_BASE_NUM;
@@ -248,8 +249,29 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
/* intersect scene */
Intersection isect;
uint visibility = path_state_ray_visibility(kg, &state);
bool hit = scene_intersect(kg, &ray, visibility, &isect);
if(!scene_intersect(kg, &ray, visibility, &isect)) {
#ifdef __LAMP_MIS__
if(kernel_data.integrator.pdf_lights > 0.0f && !(state.flag & PATH_RAY_CAMERA)) {
/* ray starting from previous non-transparent bounce */
Ray light_ray;
light_ray.P = ray.P - ray_t*ray.D;
ray_t += isect.t;
light_ray.D = ray.D;
light_ray.t = ray_t;
light_ray.time = ray.time;
/* intersect with lamp */
float light_t = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT);
float3 emission;
if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission))
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif
if(!hit) {
/* eval background shader if nothing hit */
if(kernel_data.background.transparent && (state.flag & PATH_RAY_CAMERA)) {
L_transparent += average(throughput);
@@ -313,7 +335,8 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
#ifdef __EMISSION__
/* emission */
if(sd.flag & SD_EMISSION) {
float3 emission = indirect_emission(kg, &sd, isect.t, state.flag, ray_pdf);
/* todo: is isect.t wrong here for transparent surfaces? */
float3 emission = indirect_primitive_emission(kg, &sd, isect.t, state.flag, ray_pdf);
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif
@@ -374,18 +397,19 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
Ray light_ray;
BsdfEval L_light;
bool is_lamp;
int lamp;
#ifdef __OBJECT_MOTION__
light_ray.time = sd.time;
#endif
if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &lamp)) {
/* trace shadow ray */
float3 shadow;
if(!shadow_blocked(kg, &state, &light_ray, &shadow)) {
/* accumulate */
bool is_lamp = (lamp != ~0);
path_radiance_accum_light(&L, throughput, &L_light, shadow, state.bounce, is_lamp);
}
}
@@ -422,6 +446,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
/* set labels */
if(!(label & LABEL_TRANSPARENT)) {
ray_pdf = bsdf_pdf;
ray_t = 0.0f;
min_ray_pdf = fminf(bsdf_pdf, min_ray_pdf);
}
@@ -459,13 +484,36 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
__device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray ray, __global float *buffer,
float3 throughput, float min_ray_pdf, float ray_pdf, PathState state, int rng_offset, PathRadiance *L)
{
float ray_t = 0.0f;
/* path iteration */
for(;; rng_offset += PRNG_BOUNCE_NUM) {
/* intersect scene */
Intersection isect;
uint visibility = path_state_ray_visibility(kg, &state);
bool hit = scene_intersect(kg, &ray, visibility, &isect);
if(!scene_intersect(kg, &ray, visibility, &isect)) {
#ifdef __LAMP_MIS__
if(kernel_data.integrator.pdf_lights > 0.0f && !(state.flag & PATH_RAY_CAMERA)) {
/* ray starting from previous non-transparent bounce */
Ray light_ray;
light_ray.P = ray.P - ray_t*ray.D;
ray_t += isect.t;
light_ray.D = ray.D;
light_ray.t = ray_t;
light_ray.time = ray.time;
/* intersect with lamp */
float light_t = path_rng(kg, rng, sample, rng_offset + PRNG_LIGHT);
float3 emission;
if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission))
path_radiance_accum_emission(L, throughput, emission, state.bounce);
}
#endif
if(!hit) {
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf);
@@ -496,7 +544,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
#ifdef __EMISSION__
/* emission */
if(sd.flag & SD_EMISSION) {
float3 emission = indirect_emission(kg, &sd, isect.t, state.flag, ray_pdf);
float3 emission = indirect_primitive_emission(kg, &sd, isect.t, state.flag, ray_pdf);
path_radiance_accum_emission(L, throughput, emission, state.bounce);
}
#endif
@@ -557,19 +605,20 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
Ray light_ray;
BsdfEval L_light;
bool is_lamp;
int lamp;
#ifdef __OBJECT_MOTION__
light_ray.time = sd.time;
#endif
/* sample random light */
if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &lamp)) {
/* trace shadow ray */
float3 shadow;
if(!shadow_blocked(kg, &state, &light_ray, &shadow)) {
/* accumulate */
bool is_lamp = (lamp != ~0);
path_radiance_accum_light(L, throughput, &L_light, shadow, state.bounce, is_lamp);
}
}
@@ -606,6 +655,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
/* set labels */
if(!(label & LABEL_TRANSPARENT)) {
ray_pdf = bsdf_pdf;
ray_t = 0.0f;
min_ray_pdf = fminf(bsdf_pdf, min_ray_pdf);
}
@@ -697,7 +747,7 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
#ifdef __EMISSION__
/* emission */
if(sd.flag & SD_EMISSION) {
float3 emission = indirect_emission(kg, &sd, isect.t, state.flag, ray_pdf);
float3 emission = indirect_primitive_emission(kg, &sd, isect.t, state.flag, ray_pdf);
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif
@@ -760,7 +810,7 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
if(sd.flag & SD_BSDF_HAS_EVAL) {
Ray light_ray;
BsdfEval L_light;
bool is_lamp;
int lamp;
#ifdef __OBJECT_MOTION__
light_ray.time = sd.time;
@@ -778,12 +828,13 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
float light_u = path_rng(kg, rng, sample*num_samples + j, rng_offset + PRNG_LIGHT_U);
float light_v = path_rng(kg, rng, sample*num_samples + j, rng_offset + PRNG_LIGHT_V);
if(direct_emission(kg, &sd, i, 0.0f, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
if(direct_emission(kg, &sd, i, 0.0f, 0.0f, light_u, light_v, &light_ray, &L_light, &lamp)) {
/* trace shadow ray */
float3 shadow;
if(!shadow_blocked(kg, &state, &light_ray, &shadow)) {
/* accumulate */
bool is_lamp = (lamp != ~0);
path_radiance_accum_light(&L, throughput*num_samples_inv, &L_light, shadow, state.bounce, is_lamp);
}
}
@@ -807,12 +858,13 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
if(kernel_data.integrator.num_all_lights)
light_t = 0.5f*light_t;
if(direct_emission(kg, &sd, -1, light_t, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
if(direct_emission(kg, &sd, -1, light_t, 0.0f, light_u, light_v, &light_ray, &L_light, &lamp)) {
/* trace shadow ray */
float3 shadow;
if(!shadow_blocked(kg, &state, &light_ray, &shadow)) {
/* accumulate */
bool is_lamp = (lamp != ~0);
path_radiance_accum_light(&L, throughput*num_samples_inv, &L_light, shadow, state.bounce, is_lamp);
}
}
@@ -885,7 +937,7 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
bsdf_ray.time = sd.time;
#endif
kernel_path_indirect(kg, rng, sample*num_samples, bsdf_ray, buffer,
kernel_path_indirect(kg, rng, sample*num_samples + j, bsdf_ray, buffer,
tp*num_samples_inv, min_ray_pdf, bsdf_pdf, ps, rng_offset+PRNG_BOUNCE_NUM, &L);
}
}