Weizhen Huang
ee89f213de
Uses a light tree to more effectively sample scenes with many lights. This can significantly reduce noise, at the cost of a somewhat longer render time per sample. Light tree sampling is enabled by default. It can be disabled in the Sampling > Lights panel. Scenes using light clamping or ray visibility tricks may render different as these are biased techniques that depend on the sampling strategy. The implementation is currently disabled on AMD HIP. This is planned to be fixed before the release. Implementation by Jeffrey Liu, Weizhen Huang, Alaska and Brecht Van Lommel. Ref T77889
137 lines
4.0 KiB
C++
137 lines
4.0 KiB
C++
/* SPDX-License-Identifier: Apache-2.0
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* Copyright 2011-2022 Blender Foundation */
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#pragma once
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#include "kernel/light/common.h"
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CCL_NAMESPACE_BEGIN
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template<bool in_volume_segment>
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ccl_device_inline bool point_light_sample(const ccl_global KernelLight *klight,
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const float randu,
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const float randv,
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const float3 P,
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ccl_private LightSample *ls)
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{
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float3 center = klight->co;
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float radius = klight->spot.radius;
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/* disk oriented normal */
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const float3 lightN = normalize(P - center);
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ls->P = center;
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if (radius > 0.0f) {
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ls->P += disk_light_sample(lightN, randu, randv) * radius;
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}
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ls->pdf = klight->spot.invarea;
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ls->D = normalize_len(ls->P - P, &ls->t);
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/* we set the light normal to the outgoing direction to support texturing */
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ls->Ng = -ls->D;
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ls->eval_fac = M_1_PI_F * 0.25f * klight->spot.invarea;
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if (!in_volume_segment && ls->eval_fac == 0.0f) {
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return false;
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}
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float2 uv = map_to_sphere(ls->Ng);
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ls->u = uv.x;
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ls->v = uv.y;
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ls->pdf *= lamp_light_pdf(lightN, -ls->D, ls->t);
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return true;
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}
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ccl_device_forceinline void point_light_update_position(const ccl_global KernelLight *klight,
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ccl_private LightSample *ls,
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const float3 P)
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{
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ls->D = normalize_len(ls->P - P, &ls->t);
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ls->Ng = -ls->D;
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float2 uv = map_to_sphere(ls->Ng);
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ls->u = uv.x;
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ls->v = uv.y;
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float invarea = klight->spot.invarea;
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ls->eval_fac = (0.25f * M_1_PI_F) * invarea;
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ls->pdf = invarea;
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}
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ccl_device_inline bool point_light_intersect(const ccl_global KernelLight *klight,
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const ccl_private Ray *ccl_restrict ray,
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ccl_private float *t)
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{
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/* Sphere light (aka, aligned disk light). */
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const float3 lightP = klight->co;
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const float radius = klight->spot.radius;
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if (radius == 0.0f) {
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return false;
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}
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/* disk oriented normal */
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const float3 lightN = normalize(ray->P - lightP);
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float3 P;
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return ray_disk_intersect(ray->P, ray->D, ray->tmin, ray->tmax, lightP, lightN, radius, &P, t);
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}
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ccl_device_inline bool point_light_sample_from_intersection(
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const ccl_global KernelLight *klight,
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ccl_private const Intersection *ccl_restrict isect,
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const float3 ray_P,
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const float3 ray_D,
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ccl_private LightSample *ccl_restrict ls)
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{
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const float3 lighN = normalize(ray_P - klight->co);
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/* We set the light normal to the outgoing direction to support texturing. */
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ls->Ng = -ls->D;
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float invarea = klight->spot.invarea;
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ls->eval_fac = (0.25f * M_1_PI_F) * invarea;
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ls->pdf = invarea;
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if (ls->eval_fac == 0.0f) {
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return false;
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}
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float2 uv = map_to_sphere(ls->Ng);
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ls->u = uv.x;
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ls->v = uv.y;
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/* compute pdf */
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if (ls->t != FLT_MAX) {
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ls->pdf *= lamp_light_pdf(lighN, -ls->D, ls->t);
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}
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else {
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ls->pdf = 0.f;
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}
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return true;
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}
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template<bool in_volume_segment>
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ccl_device_forceinline bool point_light_tree_parameters(const ccl_global KernelLight *klight,
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const float3 centroid,
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const float3 P,
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ccl_private float &cos_theta_u,
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ccl_private float2 &distance,
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ccl_private float3 &point_to_centroid)
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{
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if (in_volume_segment) {
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cos_theta_u = 1.0f; /* Any value in [-1, 1], irrelevant since theta = 0 */
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return true;
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}
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float min_distance;
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point_to_centroid = safe_normalize_len(centroid - P, &min_distance);
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const float radius = klight->spot.radius;
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const float hypotenus = sqrtf(sqr(radius) + sqr(min_distance));
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cos_theta_u = min_distance / hypotenus;
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distance = make_float2(hypotenus, min_distance);
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return true;
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}
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CCL_NAMESPACE_END
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