Cleanup: renaming `tan_spread` to `cot_half_spread` to avoid ambiguity
Differential Revision: https://developer.blender.org/D16695
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@ -91,7 +91,7 @@ ccl_device_inline float area_light_rect_sample(float3 P,
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ccl_device float area_light_spread_attenuation(const float3 D,
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const float3 lightNg,
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const float tan_spread,
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const float cot_half_spread,
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const float normalize_spread)
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{
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/* Model a soft-box grid, computing the ratio of light not hidden by the
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@ -99,7 +99,7 @@ ccl_device float area_light_spread_attenuation(const float3 D,
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const float cos_a = -dot(D, lightNg);
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const float sin_a = safe_sqrtf(1.0f - sqr(cos_a));
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const float tan_a = sin_a / cos_a;
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return max((1.0f - (tan_spread * tan_a)) * normalize_spread, 0.0f);
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return max((1.0f - (cot_half_spread * tan_a)) * normalize_spread, 0.0f);
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}
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/* Compute subset of area light that actually has an influence on the shading point, to
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@ -111,14 +111,14 @@ ccl_device bool area_light_spread_clamp_area_light(const float3 P,
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ccl_private float *len_u,
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const float3 axis_v,
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ccl_private float *len_v,
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const float tan_spread)
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const float cot_half_spread)
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{
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/* Closest point in area light plane and distance to that plane. */
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const float3 closest_P = P - dot(lightNg, P - *lightP) * lightNg;
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const float t = len(closest_P - P);
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/* Radius of circle on area light that actually affects the shading point. */
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const float radius = t / tan_spread;
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const float radius = t / cot_half_spread;
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/* Local uv coordinates of closest point. */
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const float closest_u = dot(axis_u, closest_P - *lightP);
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@ -186,7 +186,7 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
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float sample_len_u = len_u;
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float sample_len_v = len_v;
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if (!in_volume_segment && klight->area.tan_spread > 0.0f) {
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if (!in_volume_segment && klight->area.cot_half_spread > 0.0f) {
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if (!area_light_spread_clamp_area_light(P,
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Ng,
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&ls->P,
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@ -194,7 +194,7 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
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&sample_len_u,
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axis_v,
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&sample_len_v,
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klight->area.tan_spread)) {
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klight->area.cot_half_spread)) {
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return false;
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}
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}
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@ -216,10 +216,10 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
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ls->eval_fac = 0.25f * invarea;
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if (klight->area.tan_spread > 0.0f) {
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if (klight->area.cot_half_spread > 0.0f) {
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/* Area Light spread angle attenuation */
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ls->eval_fac *= area_light_spread_attenuation(
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ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread);
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ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
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}
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if (is_round) {
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@ -237,10 +237,10 @@ ccl_device_forceinline void area_light_update_position(const ccl_global KernelLi
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ls->D = normalize_len(ls->P - P, &ls->t);
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ls->pdf = invarea;
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if (klight->area.tan_spread > 0.f) {
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if (klight->area.cot_half_spread > 0.f) {
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ls->eval_fac = 0.25f * invarea;
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ls->eval_fac *= area_light_spread_attenuation(
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ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread);
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ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
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}
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}
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@ -313,7 +313,7 @@ ccl_device_inline bool area_light_sample_from_intersection(
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float sample_len_u = klight->area.len_u;
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float sample_len_v = klight->area.len_v;
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if (klight->area.tan_spread > 0.0f) {
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if (klight->area.cot_half_spread > 0.0f) {
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if (!area_light_spread_clamp_area_light(ray_P,
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Ng,
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&light_P,
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@ -321,7 +321,7 @@ ccl_device_inline bool area_light_sample_from_intersection(
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&sample_len_u,
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axis_v,
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&sample_len_v,
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klight->area.tan_spread)) {
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klight->area.cot_half_spread)) {
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return false;
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}
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}
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@ -331,10 +331,10 @@ ccl_device_inline bool area_light_sample_from_intersection(
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}
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ls->eval_fac = 0.25f * invarea;
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if (klight->area.tan_spread > 0.0f) {
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if (klight->area.cot_half_spread > 0.0f) {
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/* Area Light spread angle attenuation */
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ls->eval_fac *= area_light_spread_attenuation(
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ls->D, ls->Ng, klight->area.tan_spread, klight->area.normalize_spread);
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ls->D, ls->Ng, klight->area.cot_half_spread, klight->area.normalize_spread);
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if (ls->eval_fac == 0.0f) {
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return false;
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}
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@ -1307,7 +1307,7 @@ typedef struct KernelAreaLight {
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float len_v;
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packed_float3 dir;
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float invarea;
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float tan_spread;
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float cot_half_spread;
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float normalize_spread;
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float pad[2];
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} KernelAreaLight;
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@ -1038,14 +1038,14 @@ void LightManager::device_update_lights(Device *device, DeviceScene *dscene, Sce
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float invarea = (area != 0.0f) ? 1.0f / area : 1.0f;
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float3 dir = light->dir;
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/* Convert from spread angle 0..180 to 90..0, clamping to a minimum
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* angle to avoid excessive noise. */
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const float min_spread_angle = 1.0f * M_PI_F / 180.0f;
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const float spread_angle = 0.5f * (M_PI_F - max(light->spread, min_spread_angle));
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/* Clamping to a minimum angle to avoid excessive noise. */
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const float min_spread = 1.0f * M_PI_F / 180.0f;
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const float half_spread = 0.5f * max(light->spread, min_spread);
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/* cot_half_spread is h in D10594#269626 */
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const float cot_half_spread = tanf(M_PI_2_F - half_spread);
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/* Normalization computed using:
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* integrate cos(x) * (1 - tan(x) * tan(a)) * sin(x) from x = 0 to pi/2 - a. */
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const float tan_spread = tanf(spread_angle);
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const float normalize_spread = 2.0f / (2.0f + (2.0f * spread_angle - M_PI_F) * tan_spread);
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* integrate cos(x) * (1 - tan(x) / tan(a)) * sin(x) from x = 0 to a, a being half_spread */
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const float normalize_spread = 1.0f / (1.0f - half_spread * cot_half_spread);
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dir = safe_normalize(dir);
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@ -1059,7 +1059,7 @@ void LightManager::device_update_lights(Device *device, DeviceScene *dscene, Sce
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klights[light_index].area.len_v = len_v;
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klights[light_index].area.invarea = invarea;
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klights[light_index].area.dir = dir;
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klights[light_index].area.tan_spread = tan_spread;
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klights[light_index].area.cot_half_spread = cot_half_spread;
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klights[light_index].area.normalize_spread = normalize_spread;
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}
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else if (light->light_type == LIGHT_SPOT) {
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