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Cleanup: renaming `tan_spread` to `cot_half_spread` to avoid ambiguity 

Differential Revision: https://developer.blender.org/D16695
This commit is contained in:
Weizhen Huang 2022-12-05 17:02:52 +01:00
parent ee89f213de
commit f646a4f22c
3 changed files with 23 additions and 23 deletions
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28
intern/cycles/kernel/light/area.h
View File

@ -91,7 +91,7 @@ ccl_device_inline float area_light_rect_sample(float3 P,
ccl_device float area_light_spread_attenuation(const float3 D, ccl_device float area_light_spread_attenuation(const float3 D,
const float3 lightNg, const float3 lightNg,
const float tan_spread, const float cot_half_spread,
const float normalize_spread) const float normalize_spread)
{ {
/* Model a soft-box grid, computing the ratio of light not hidden by the /* Model a soft-box grid, computing the ratio of light not hidden by the
@ -99,7 +99,7 @@ ccl_device float area_light_spread_attenuation(const float3 D,
const float cos_a = -dot(D, lightNg); const float cos_a = -dot(D, lightNg);
const float sin_a = safe_sqrtf(1.0f - sqr(cos_a)); const float sin_a = safe_sqrtf(1.0f - sqr(cos_a));
const float tan_a = sin_a / cos_a; const float tan_a = sin_a / cos_a;
return max((1.0f - (tan_spread * tan_a)) * normalize_spread, 0.0f); return max((1.0f - (cot_half_spread * tan_a)) * normalize_spread, 0.0f);
} }
/* Compute subset of area light that actually has an influence on the shading point, to /* Compute subset of area light that actually has an influence on the shading point, to
@ -111,14 +111,14 @@ ccl_device bool area_light_spread_clamp_area_light(const float3 P,
ccl_private float *len_u, ccl_private float *len_u,
const float3 axis_v, const float3 axis_v,
ccl_private float *len_v, ccl_private float *len_v,
const float tan_spread) const float cot_half_spread)
{ {
/* Closest point in area light plane and distance to that plane. */ /* Closest point in area light plane and distance to that plane. */
const float3 closest_P = P - dot(lightNg, P - *lightP) * lightNg; const float3 closest_P = P - dot(lightNg, P - *lightP) * lightNg;
const float t = len(closest_P - P); const float t = len(closest_P - P);
/* Radius of circle on area light that actually affects the shading point. */ /* Radius of circle on area light that actually affects the shading point. */
const float radius = t / tan_spread; const float radius = t / cot_half_spread;
/* Local uv coordinates of closest point. */ /* Local uv coordinates of closest point. */
const float closest_u = dot(axis_u, closest_P - *lightP); const float closest_u = dot(axis_u, closest_P - *lightP);
@ -186,7 +186,7 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
float sample_len_u = len_u; float sample_len_u = len_u;
float sample_len_v = len_v; float sample_len_v = len_v;
if (!in_volume_segment && klight->area.tan_spread > 0.0f) { if (!in_volume_segment && klight->area.cot_half_spread > 0.0f) {
if (!area_light_spread_clamp_area_light(P, if (!area_light_spread_clamp_area_light(P,
Ng, Ng,
&ls->P, &ls->P,
@ -194,7 +194,7 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
&sample_len_u, &sample_len_u,
axis_v, axis_v,
&sample_len_v, &sample_len_v,
klight->area.tan_spread)) { klight->area.cot_half_spread)) {
return false; return false;
} }
} }
@ -216,10 +216,10 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
ls->eval_fac = 0.25f * invarea; ls->eval_fac = 0.25f * invarea;
if (klight->area.tan_spread > 0.0f) { if (klight->area.cot_half_spread > 0.0f) {
/* Area Light spread angle attenuation */ /* Area Light spread angle attenuation */
ls->eval_fac *= area_light_spread_attenuation( ls->eval_fac *= area_light_spread_attenuation(
ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread); ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
} }
if (is_round) { if (is_round) {
@ -237,10 +237,10 @@ ccl_device_forceinline void area_light_update_position(const ccl_global KernelLi
ls->D = normalize_len(ls->P - P, &ls->t); ls->D = normalize_len(ls->P - P, &ls->t);
ls->pdf = invarea; ls->pdf = invarea;
if (klight->area.tan_spread > 0.f) { if (klight->area.cot_half_spread > 0.f) {
ls->eval_fac = 0.25f * invarea; ls->eval_fac = 0.25f * invarea;
ls->eval_fac *= area_light_spread_attenuation( ls->eval_fac *= area_light_spread_attenuation(
ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread); ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
} }
} }
@ -313,7 +313,7 @@ ccl_device_inline bool area_light_sample_from_intersection(
float sample_len_u = klight->area.len_u; float sample_len_u = klight->area.len_u;
float sample_len_v = klight->area.len_v; float sample_len_v = klight->area.len_v;
if (klight->area.tan_spread > 0.0f) { if (klight->area.cot_half_spread > 0.0f) {
if (!area_light_spread_clamp_area_light(ray_P, if (!area_light_spread_clamp_area_light(ray_P,
Ng, Ng,
&light_P, &light_P,
@ -321,7 +321,7 @@ ccl_device_inline bool area_light_sample_from_intersection(
&sample_len_u, &sample_len_u,
axis_v, axis_v,
&sample_len_v, &sample_len_v,
klight->area.tan_spread)) { klight->area.cot_half_spread)) {
return false; return false;
} }
} }
@ -331,10 +331,10 @@ ccl_device_inline bool area_light_sample_from_intersection(
} }
ls->eval_fac = 0.25f * invarea; ls->eval_fac = 0.25f * invarea;
if (klight->area.tan_spread > 0.0f) { if (klight->area.cot_half_spread > 0.0f) {
/* Area Light spread angle attenuation */ /* Area Light spread angle attenuation */
ls->eval_fac *= area_light_spread_attenuation( ls->eval_fac *= area_light_spread_attenuation(
ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread); ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
if (ls->eval_fac == 0.0f) { if (ls->eval_fac == 0.0f) {
return false; return false;
} }

2
intern/cycles/kernel/types.h
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@ -1307,7 +1307,7 @@ typedef struct KernelAreaLight {
float len_v; float len_v;
packed_float3 dir; packed_float3 dir;
float invarea; float invarea;
float tan_spread; float cot_half_spread;
float normalize_spread; float normalize_spread;
float pad[2]; float pad[2];
} KernelAreaLight; } KernelAreaLight;

16
intern/cycles/scene/light.cpp
View File

@ -1038,14 +1038,14 @@ void LightManager::device_update_lights(Device *device, DeviceScene *dscene, Sce
float invarea = (area != 0.0f) ? 1.0f / area : 1.0f; float invarea = (area != 0.0f) ? 1.0f / area : 1.0f;
float3 dir = light->dir; float3 dir = light->dir;
/* Convert from spread angle 0..180 to 90..0, clamping to a minimum /* Clamping to a minimum angle to avoid excessive noise. */
* angle to avoid excessive noise. */ const float min_spread = 1.0f * M_PI_F / 180.0f;
const float min_spread_angle = 1.0f * M_PI_F / 180.0f; const float half_spread = 0.5f * max(light->spread, min_spread);
const float spread_angle = 0.5f * (M_PI_F - max(light->spread, min_spread_angle)); /* cot_half_spread is h in D10594#269626 */
const float cot_half_spread = tanf(M_PI_2_F - half_spread);
/* Normalization computed using: /* Normalization computed using:
* integrate cos(x) * (1 - tan(x) * tan(a)) * sin(x) from x = 0 to pi/2 - a. */ * integrate cos(x) * (1 - tan(x) / tan(a)) * sin(x) from x = 0 to a, a being half_spread */
const float tan_spread = tanf(spread_angle); const float normalize_spread = 1.0f / (1.0f - half_spread * cot_half_spread);
const float normalize_spread = 2.0f / (2.0f + (2.0f * spread_angle - M_PI_F) * tan_spread);
dir = safe_normalize(dir); dir = safe_normalize(dir);
@ -1059,7 +1059,7 @@ void LightManager::device_update_lights(Device *device, DeviceScene *dscene, Sce
klights[light_index].area.len_v = len_v; klights[light_index].area.len_v = len_v;
klights[light_index].area.invarea = invarea; klights[light_index].area.invarea = invarea;
klights[light_index].area.dir = dir; klights[light_index].area.dir = dir;
klights[light_index].area.tan_spread = tan_spread; klights[light_index].area.cot_half_spread = cot_half_spread;
klights[light_index].area.normalize_spread = normalize_spread; klights[light_index].area.normalize_spread = normalize_spread;
} }
else if (light->light_type == LIGHT_SPOT) { else if (light->light_type == LIGHT_SPOT) {