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#include "render.hpp"
#include "vector.hpp"
#include "common.hpp"
#include <cstdlib>
#include <math.h>
#include <iostream>
#define FOV 1.74533
// Uniform sampling
#define SAMPLING_POWER 0
const Vec3d up = Vec3d(0, 1, 0);
void Random::seed(unsigned seed) {
for (unsigned i = 0; i < seed; i++) {
rand_r(&m_seed);
}
}
double Random::operator()() {
return (double)rand_r(&m_seed) / (double)RAND_MAX;
}
Sampler::Sampler(Random &src) : m_src(src) { }
Vec3d Sampler::sample(const Vec3d &norm) {
/*
auto theta = asin(pow(1 - random(), (double)1 / (1 + SAMPLING_POWER)));
auto phi = 2 * M_PI * random();
*/
auto theta = 2.0 * M_PI * m_src();
auto phi = acos(2.0 * m_src() - 1.0);
auto sinphi = sin(phi);
auto newvec = Vec3d(cos(theta) * sinphi, sin(theta) * sinphi, cos(phi));
if (newvec.dot(norm) <= 0) {
newvec = -newvec;
}
return newvec;
}
Renderer::Renderer(const Scene &scn, Vec3d eye, Vec3d target, unsigned width, unsigned height, unsigned maxhops) :
m_sampler(m_random),
m_scn(scn)
{
m_eye = eye;
m_target = target;
m_width = width;
m_height = height;
m_maxhops = maxhops;
recalculate();
}
void Renderer::recalculate() {
auto tmp = m_target - m_eye;
// Orthogonal vector to E
auto b = up.cross(tmp);
b.normalize();
tmp.normalize();
auto v = tmp.cross(b);
// Calculate size of viewplane
double gx = tan( FOV / 2);
double gy = gx * ((double) m_height / m_width);
// Calculate scaling vectors
m_qx = b * ((2 * gx) / (m_width - 1));
m_qy = v * ((2 * gy) / (m_height - 1));
// Calculate starting point
m_blc = tmp - (b * gx) - (v * gy);
}
Ray Renderer::findray(double x, double y) const {
auto dir = m_blc + (m_qx * x) + (m_qy * y);
return Ray(m_eye, dir, true);
}
Color Renderer::render(unsigned x, unsigned y, unsigned samples) {
Color sum(0, 0, 0);
for (unsigned i = 0; i < samples; i++) {
auto r = findray(x + m_random(), y + m_random());
sum += pathtrace_sample(r, 0);
}
if (samples < 2) {
return sum;
} else {
return Vec3d(sum) / (double)samples;
}
}
Color Renderer::pathtrace_sample(const Ray &r, unsigned hop) {
if (hop >= m_maxhops) {
return Color(0, 0, 0);
}
double dist;
auto res = cast_ray(r, 0, &dist);
if (!res) {
return Color(0, 0, 0);
}
auto col = res->m_mat.emits();
if (res->m_mat.reflects()) {
// Calculate endpoint
auto end = r.m_start + r.m_direction * dist;
auto norm = res->norm_at(end, r.m_direction);
auto randdir = m_sampler.sample(norm);
auto newray = Ray(end, randdir, true);
auto incol = pathtrace_sample(newray, hop+1);
col += res->m_mat.reflect(norm, r.m_direction, newray.m_direction, incol);
}
return col;
}
const Shape* Renderer::cast_ray(const Ray &r, double chk_dist, double *dist_ret) {
const Shape *smallest = nullptr;
double dist = 0;
for (auto obj : m_scn.objs) {
if (!obj) {
continue;
}
auto d = obj->intersect(r, false);
if (d > ZERO_APPROX) {
if (chk_dist > 0 && d < chk_dist) {
dist = d; smallest = obj;
goto exit;
}
if (d < dist || smallest == nullptr) {
dist = d; smallest = obj;
}
}
}
if (chk_dist > 0) {
// If we reach this it means none of the
// object where within distance.
return nullptr;
}
exit:
if (dist_ret) {
*dist_ret = dist;
}
return smallest;
}
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