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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2011-2022 Blender Foundation */
#pragma once
#include "kernel/light/common.h"
CCL_NAMESPACE_BEGIN
ccl_device float spot_light_attenuation(float3 dir,
float cos_half_spot_angle,
float spot_smooth,
float3 N)
{
float attenuation = dot(dir, N);
if (attenuation <= cos_half_spot_angle) {
attenuation = 0.0f;
}
else {
float t = attenuation - cos_half_spot_angle;
if (t < spot_smooth && spot_smooth != 0.0f)
attenuation *= smoothstepf(t / spot_smooth);
}
return attenuation;
}
template<bool in_volume_segment>
ccl_device_inline bool spot_light_sample(const ccl_global KernelLight *klight,
const float randu,
const float randv,
const float3 P,
ccl_private LightSample *ls)
{
ls->P = make_float3(klight->co[0], klight->co[1], klight->co[2]);
const float3 center = make_float3(klight->co[0], klight->co[1], klight->co[2]);
const float radius = klight->spot.radius;
const float3 dir = make_float3(klight->spot.dir[0], klight->spot.dir[1], klight->spot.dir[2]);
/* disk oriented normal */
const float3 lightN = normalize(P - center);
ls->P = center;
if (radius > 0.0f) {
/* disk light */
ls->P += disk_light_sample(lightN, randu, randv) * radius;
}
const float invarea = klight->spot.invarea;
ls->pdf = invarea;
ls->D = normalize_len(ls->P - P, &ls->t);
/* we set the light normal to the outgoing direction to support texturing */
ls->Ng = -ls->D;
ls->eval_fac = (0.25f * M_1_PI_F) * invarea;
/* spot light attenuation */
ls->eval_fac *= spot_light_attenuation(
dir, klight->spot.cos_half_spot_angle, klight->spot.spot_smooth, -ls->D);
if (!in_volume_segment && ls->eval_fac == 0.0f) {
return false;
}
float2 uv = map_to_sphere(ls->Ng);
ls->u = uv.x;
ls->v = uv.y;
ls->pdf *= lamp_light_pdf(lightN, -ls->D, ls->t);
return true;
}
ccl_device_forceinline void spot_light_update_position(const ccl_global KernelLight *klight,
ccl_private LightSample *ls,
const float3 P)
{
ls->D = normalize_len(ls->P - P, &ls->t);
ls->Ng = -ls->D;
float2 uv = map_to_sphere(ls->Ng);
ls->u = uv.x;
ls->v = uv.y;
float invarea = klight->spot.invarea;
ls->eval_fac = (0.25f * M_1_PI_F) * invarea;
ls->pdf = invarea;
/* spot light attenuation */
float3 dir = make_float3(klight->spot.dir[0], klight->spot.dir[1], klight->spot.dir[2]);
ls->eval_fac *= spot_light_attenuation(
dir, klight->spot.cos_half_spot_angle, klight->spot.spot_smooth, ls->Ng);
}
ccl_device_inline bool spot_light_intersect(const ccl_global KernelLight *klight,
const ccl_private Ray *ccl_restrict ray,
ccl_private float *t)
{
/* Spot/Disk light. */
const float3 lightP = make_float3(klight->co[0], klight->co[1], klight->co[2]);
const float radius = klight->spot.radius;
if (radius == 0.0f) {
return false;
}
/* disk oriented normal */
const float3 lightN = normalize(ray->P - lightP);
/* One sided. */
if (dot(ray->D, lightN) >= 0.0f) {
return false;
}
float3 P;
return ray_disk_intersect(ray->P, ray->D, ray->tmin, ray->tmax, lightP, lightN, radius, &P, t);
}
ccl_device_inline bool spot_light_sample_from_intersection(
const ccl_global KernelLight *klight,
ccl_private const Intersection *ccl_restrict isect,
const float3 ray_P,
const float3 ray_D,
ccl_private LightSample *ccl_restrict ls)
{
const float3 center = make_float3(klight->co[0], klight->co[1], klight->co[2]);
const float3 dir = make_float3(klight->spot.dir[0], klight->spot.dir[1], klight->spot.dir[2]);
/* the normal of the oriented disk */
const float3 lightN = normalize(ray_P - center);
/* We set the light normal to the outgoing direction to support texturing. */
ls->Ng = -ls->D;
float invarea = klight->spot.invarea;
ls->eval_fac = (0.25f * M_1_PI_F) * invarea;
ls->pdf = invarea;
/* spot light attenuation */
ls->eval_fac *= spot_light_attenuation(
dir, klight->spot.cos_half_spot_angle, klight->spot.spot_smooth, -ls->D);
if (ls->eval_fac == 0.0f) {
return false;
}
float2 uv = map_to_sphere(ls->Ng);
ls->u = uv.x;
ls->v = uv.y;
/* compute pdf */
if (ls->t != FLT_MAX) {
ls->pdf *= lamp_light_pdf(lightN, -ls->D, ls->t);
}
else {
ls->pdf = 0.f;
}
return true;
}
ccl_device_inline float spot_light_tree_weight(const ccl_global KernelLight *klight,
const float3 P,
const float3 N)
{
const float3 light_P = make_float3(klight->co[0], klight->co[1], klight->co[2]);
const float radius = klight->spot.radius;
const float cos_theta = klight->spot.cos_half_spot_angle;
const float theta = fast_acosf(cos_theta);
const float3 light_dir = make_float3(
klight->spot.dir[0], klight->spot.dir[1], klight->spot.dir[2]);
const float h1 = radius * fast_sinf(theta);
const float d1 = radius * cos_theta;
const float h2 = d1 / fast_tanf(theta);
const float3 apex = light_P - (h1 + h2) * light_dir;
const float3 apex_to_point = normalize(P - apex);
return (dot(apex_to_point, light_dir) < cos_theta) ? 0.0f : 1.0f;
}
CCL_NAMESPACE_END
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