forked from bartvdbraak/blender
1284e98ab8
based on concentric disk mapping. Concentric disk mapping was already present, but not used everywhere. Now `sample_cos_hemisphere()`, `sample_uniform_hemisphere()`, and `sample_uniform_cone()` use concentric disk mapping. This changes the noise in many test images. Pull Request: https://projects.blender.org/blender/blender/pulls/109774
149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#pragma once
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#include "kernel/geom/geom.h"
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#include "kernel/light/common.h"
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CCL_NAMESPACE_BEGIN
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ccl_device_inline void distant_light_uv(const ccl_global KernelLight *klight,
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const float3 D,
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ccl_private float *u,
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ccl_private float *v)
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{
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/* Map direction (x, y, z) to disk [-0.5, 0.5]^2:
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* r^2 = (1 - z) / (1 - cos(klight->distant.angle))
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* u_ = 0.5 * x * r / sin_angle(D, -klight->co)
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* v_ = 0.5 * y * r / sin_angle(D, -klight->co) */
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const float fac = klight->distant.half_inv_sin_half_angle / len(D - klight->co);
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/* Get u axis and v axis. */
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const Transform itfm = klight->itfm;
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const float u_ = dot(D, float4_to_float3(itfm.x)) * fac;
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const float v_ = dot(D, float4_to_float3(itfm.y)) * fac;
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/* NOTE: Return barycentric coordinates in the same notation as Embree and OptiX. */
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*u = v_ + 0.5f;
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*v = -u_ - v_;
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}
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ccl_device_inline bool distant_light_sample(const ccl_global KernelLight *klight,
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const float2 rand,
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ccl_private LightSample *ls)
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{
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float unused;
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ls->Ng = sample_uniform_cone(
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klight->co, klight->distant.one_minus_cosangle, rand, &unused, &ls->pdf);
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ls->P = ls->Ng;
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ls->D = -ls->Ng;
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ls->t = FLT_MAX;
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ls->eval_fac = klight->distant.eval_fac;
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distant_light_uv(klight, ls->D, &ls->u, &ls->v);
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return true;
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}
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/* Special intersection check.
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* Returns true if the distant_light_sample_from_intersection() for this light would return true.
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*
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* The intersection parameters t, u, v are optimized for the shadow ray towards a dedicated light:
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* u = v = 0, t = FLT_MAX.
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*/
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ccl_device bool distant_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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ccl_private float *u,
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ccl_private float *v)
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{
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kernel_assert(klight->type == LIGHT_DISTANT);
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if (klight->distant.angle == 0.0f) {
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return false;
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}
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if (vector_angle(-klight->co, ray->D) > klight->distant.angle) {
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return false;
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}
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*t = FLT_MAX;
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*u = 0.0f;
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*v = 0.0f;
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return true;
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}
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ccl_device bool distant_light_sample_from_intersection(KernelGlobals kg,
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const float3 ray_D,
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const int lamp,
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ccl_private LightSample *ccl_restrict ls)
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{
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ccl_global const KernelLight *klight = &kernel_data_fetch(lights, lamp);
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const int shader = klight->shader_id;
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const LightType type = (LightType)klight->type;
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if (type != LIGHT_DISTANT) {
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return false;
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}
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if (!(shader & SHADER_USE_MIS)) {
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return false;
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}
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if (klight->distant.angle == 0.0f) {
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return false;
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}
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/* Workaround to prevent a hang in the classroom scene with AMD HIP drivers 22.10,
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* Remove when a compiler fix is available. */
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#ifdef __HIP__
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ls->shader = klight->shader_id;
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#endif
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if (vector_angle(-klight->co, ray_D) > klight->distant.angle) {
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return false;
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}
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ls->type = type;
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#ifndef __HIP__
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ls->shader = klight->shader_id;
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#endif
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ls->object = PRIM_NONE;
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ls->prim = PRIM_NONE;
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ls->lamp = lamp;
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ls->t = FLT_MAX;
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ls->P = -ray_D;
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ls->Ng = -ray_D;
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ls->D = ray_D;
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ls->group = lamp_lightgroup(kg, lamp);
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ls->pdf = klight->distant.pdf;
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ls->eval_fac = klight->distant.eval_fac;
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distant_light_uv(klight, ray_D, &ls->u, &ls->v);
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return true;
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}
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ccl_device_forceinline bool distant_light_tree_parameters(const float3 centroid,
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const float theta_e,
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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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/* Treating it as a disk light 1 unit away */
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cos_theta_u = fast_cosf(theta_e);
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distance = make_float2(1.0f / cos_theta_u, 1.0f);
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point_to_centroid = -centroid;
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return true;
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}
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CCL_NAMESPACE_END
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