129 lines
4.8 KiB
C++
129 lines
4.8 KiB
C++
// Copyright 2009-2021 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#include "light.h"
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#include <sampling.hpp>
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#include <math/linearspace3.h>
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#include "helper.hpp"
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namespace embree {
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struct PointLight {
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Light super; //!< inherited light fields
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Vec3fa position; //!< light position
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Vec3fa power; //!< RGB color and intensity of light
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float radius; //!< defines the size of the SphereLight
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};
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// Implementation
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//////////////////////////////////////////////////////////////////////////////
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Light_SampleRes PointLight_sample(const Light* super,
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const Sample& dg,
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const Vec2f& s) {
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const PointLight* self = (PointLight *) super;
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Light_SampleRes res;
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// extant light vector from the hit point
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const Vec3fa dir = self->position - dg.P;
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const float dist2 = dot(dir, dir);
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const float invdist = rsqrt(dist2);
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// normalized light vector
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res.dir = dir * invdist;
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res.dist = dist2 * invdist;
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res.pdf = inf; // per default we always take this res
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// convert from power to radiance by attenuating by distance^2
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res.weight = self->power * sqr(invdist);
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const float sinTheta = self->radius * invdist;
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if ((self->radius > 0.f) & (sinTheta > 0.005f)) {
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// res surface of sphere as seen by hit point -> cone of directions
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// for very small cones treat as point light, because float precision is not good enough
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if (sinTheta < 1.f) {
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const float cosTheta = sqrt(1.f - sinTheta * sinTheta);
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const Vec3fa localDir = uniformSampleCone(cosTheta, s);
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res.dir = frame(res.dir) * localDir;
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res.pdf = uniformSampleConePDF(cosTheta);
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const float c = localDir.z;
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res.dist = c * res.dist - sqrt(sqr(self->radius) - (1.f - c * c) * dist2);
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// TODO scale radiance by actual distance
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} else {
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// inside sphere
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const Vec3fa localDir = cosineSampleHemisphere(s);
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res.dir = frame(dg.Ns) * localDir;
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res.pdf = cosineSampleHemispherePDF(localDir);
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// TODO:
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res.weight = self->power * rcp(sqr(self->radius));
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res.dist = self->radius;
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}
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}
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return res;
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}
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Light_EvalRes PointLight_eval(const Light* super,
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const Sample& dg,
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const Vec3fa& dir) {
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const PointLight* self = (PointLight *) super;
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Light_EvalRes res;
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res.value = Vec3fa(0.f);
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res.dist = inf;
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res.pdf = 0.f;
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if (self->radius > 0.f) {
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const Vec3fa A = self->position - dg.P;
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const float a = dot(dir, dir);
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const float b = 2.f * dot(dir, A);
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const float centerDist2 = dot(A, A);
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const float c = centerDist2 - sqr(self->radius);
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const float radical = sqr(b) - 4.f * a * c;
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if (radical > 0.f) {
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const float t_near = (b - sqrt(radical)) / (2.f * a);
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const float t_far = (b + sqrt(radical)) / (2.f * a);
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if (t_far > 0.0f) {
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// TODO: handle interior case
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res.dist = t_near;
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const float sinTheta2 = sqr(self->radius) * rcp(centerDist2);
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const float cosTheta = sqrt(1.f - sinTheta2);
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res.pdf = uniformSampleConePDF(cosTheta);
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const float invdist = rcp(t_near);
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res.value = self->power * res.pdf * sqr(invdist);
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}
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}
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}
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return res;
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}
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// Exports (called from C++)
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//////////////////////////////////////////////////////////////////////////////
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//! Set the parameters of an ispc-side PointLight object
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extern "C" void PointLight_set(void* super,
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const Vec3fa& position,
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const Vec3fa& power,
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float radius) {
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PointLight* self = (PointLight *) super;
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self->position = position;
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self->power = power;
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self->radius = radius;
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}
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//! Create an ispc-side PointLight object
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extern "C" void* PointLight_create() {
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PointLight* self = (PointLight *) alignedUSMMalloc(sizeof(PointLight), 16);
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Light_Constructor(&self->super);
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//self->super.sample = GET_FUNCTION_POINTER(PointLight_sample);
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//self->super.eval = GET_FUNCTION_POINTER(PointLight_eval);
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self->super.type = LIGHT_POINT;
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PointLight_set(self, Vec3fa(0.f), Vec3fa(1.f), 0.f);
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return self;
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}
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} // namespace embree
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