tinyraytracer/tinyraytracer.cpp
Dmitry V. Sokolov 5e0da1f09f checkerboard
2019-01-20 12:27:10 +01:00

172 lines
6.8 KiB
C++

#include <limits>
#include <cmath>
#include <iostream>
#include <fstream>
#include <vector>
#include "geometry.h"
struct Light {
Light(const Vec3f &p, const float &i) : position(p), intensity(i) {}
Vec3f position;
float intensity;
};
struct Material {
Material(const float &r, const Vec4f &a, const Vec3f &color, const float &spec) : refractive_index(r), albedo(a), diffuse_color(color), specular_exponent(spec) {}
Material() : refractive_index(1), albedo(1,0,0,0), diffuse_color(), specular_exponent() {}
float refractive_index;
Vec4f albedo;
Vec3f diffuse_color;
float specular_exponent;
};
struct Sphere {
Vec3f center;
float radius;
Material material;
Sphere(const Vec3f &c, const float &r, const Material &m) : center(c), radius(r), material(m) {}
bool ray_intersect(const Vec3f &orig, const Vec3f &dir, float &t0) const {
Vec3f L = center - orig;
float tca = L*dir;
float d2 = L*L - tca*tca;
if (d2 > radius*radius) return false;
float thc = sqrtf(radius*radius - d2);
t0 = tca - thc;
float t1 = tca + thc;
if (t0 < 0) t0 = t1;
if (t0 < 0) return false;
return true;
}
};
Vec3f reflect(const Vec3f &I, const Vec3f &N) {
return I - N*2.f*(I*N);
}
Vec3f refract(const Vec3f &I, const Vec3f &N, const float &refractive_index) { // Snell's law
float cosi = - std::max(-1.f, std::min(1.f, I*N));
float etai = 1, etat = refractive_index;
Vec3f n = N;
if (cosi < 0) { // if the ray is inside the object, swap the indices and invert the normal to get the correct result
cosi = -cosi;
std::swap(etai, etat); n = -N;
}
float eta = etai / etat;
float k = 1 - eta*eta*(1 - cosi*cosi);
return k < 0 ? Vec3f(0,0,0) : I*eta + n*(eta * cosi - sqrtf(k));
}
bool scene_intersect(const Vec3f &orig, const Vec3f &dir, const std::vector<Sphere> &spheres, Vec3f &hit, Vec3f &N, Material &material) {
float spheres_dist = std::numeric_limits<float>::max();
for (size_t i=0; i < spheres.size(); i++) {
float dist_i;
if (spheres[i].ray_intersect(orig, dir, dist_i) && dist_i < spheres_dist) {
spheres_dist = dist_i;
hit = orig + dir*dist_i;
N = (hit - spheres[i].center).normalize();
material = spheres[i].material;
}
}
float checkerboard_dist = std::numeric_limits<float>::max();
if (fabs(dir.y)>1e-3) {
float d = -(orig.y+4)/dir.y; // the checkerboard plane has equation y = -4
Vec3f pt = orig + dir*d;
if (d>0 && fabs(pt.x)<10 && pt.z<-10 && pt.z>-30 && d<spheres_dist) {
checkerboard_dist = d;
hit = pt;
N = Vec3f(0,1,0);
material.diffuse_color = (int(.5*hit.x+1000) + int(.5*hit.z)) & 1 ? Vec3f(1,1,1) : Vec3f(1, .7, .3);
material.diffuse_color = material.diffuse_color*.3;
}
}
return std::min(spheres_dist, checkerboard_dist)<1000;
}
Vec3f cast_ray(const Vec3f &orig, const Vec3f &dir, const std::vector<Sphere> &spheres, const std::vector<Light> &lights, size_t depth=0) {
Vec3f point, N;
Material material;
if (depth>4 || !scene_intersect(orig, dir, spheres, point, N, material)) {
return Vec3f(0.2, 0.7, 0.8); // background color
}
Vec3f reflect_dir = reflect(dir, N).normalize();
Vec3f refract_dir = refract(dir, N, material.refractive_index).normalize();
Vec3f reflect_orig = reflect_dir*N < 0 ? point - N*1e-3 : point + N*1e-3; // offset the original point to avoid occlusion by the object itself
Vec3f refract_orig = refract_dir*N < 0 ? point - N*1e-3 : point + N*1e-3;
Vec3f reflect_color = cast_ray(reflect_orig, reflect_dir, spheres, lights, depth + 1);
Vec3f refract_color = cast_ray(refract_orig, refract_dir, spheres, lights, depth + 1);
float diffuse_light_intensity = 0, specular_light_intensity = 0;
for (size_t i=0; i<lights.size(); i++) {
Vec3f light_dir = (lights[i].position - point).normalize();
float light_distance = (lights[i].position - point).norm();
Vec3f shadow_orig = light_dir*N < 0 ? point - N*1e-3 : point + N*1e-3; // checking if the point lies in the shadow of the lights[i]
Vec3f shadow_pt, shadow_N;
Material tmpmaterial;
if (scene_intersect(shadow_orig, light_dir, spheres, shadow_pt, shadow_N, tmpmaterial) && (shadow_pt-shadow_orig).norm() < light_distance)
continue;
diffuse_light_intensity += lights[i].intensity * std::max(0.f, light_dir*N);
specular_light_intensity += powf(std::max(0.f, -reflect(-light_dir, N)*dir), material.specular_exponent)*lights[i].intensity;
}
return material.diffuse_color * diffuse_light_intensity * material.albedo[0] + Vec3f(1., 1., 1.)*specular_light_intensity * material.albedo[1] + reflect_color*material.albedo[2] + refract_color*material.albedo[3];
}
void render(const std::vector<Sphere> &spheres, const std::vector<Light> &lights) {
const int width = 1024;
const int height = 768;
const int fov = M_PI/2.;
std::vector<Vec3f> framebuffer(width*height);
#pragma omp parallel for
for (size_t j = 0; j<height; j++) {
for (size_t i = 0; i<width; i++) {
float x = (2*(i + 0.5)/(float)width - 1)*tan(fov/2.)*width/(float)height;
float y = -(2*(j + 0.5)/(float)height - 1)*tan(fov/2.);
Vec3f dir = Vec3f(x, y, -1).normalize();
framebuffer[i+j*width] = cast_ray(Vec3f(0,0,0), dir, spheres, lights);
}
}
std::ofstream ofs; // save the framebuffer to file
ofs.open("./out.ppm");
ofs << "P6\n" << width << " " << height << "\n255\n";
for (size_t i = 0; i < height*width; ++i) {
Vec3f &c = framebuffer[i];
float max = std::max(c[0], std::max(c[1], c[2]));
if (max>1) c = c*(1./max);
for (size_t j = 0; j<3; j++) {
ofs << (char)(255 * std::max(0.f, std::min(1.f, framebuffer[i][j])));
}
}
ofs.close();
}
int main() {
Material ivory(1.0, Vec4f(0.6, 0.3, 0.1, 0.0), Vec3f(0.4, 0.4, 0.3), 50.);
Material glass(1.5, Vec4f(0.0, 0.5, 0.1, 0.8), Vec3f(0.6, 0.7, 0.8), 125.);
Material red_rubber(1.0, Vec4f(0.9, 0.1, 0.0, 0.0), Vec3f(0.3, 0.1, 0.1), 10.);
Material mirror(1.0, Vec4f(0.0, 10.0, 0.8, 0.0), Vec3f(1.0, 1.0, 1.0), 1425.);
std::vector<Sphere> spheres;
spheres.push_back(Sphere(Vec3f(-3, 0, -16), 2, ivory));
spheres.push_back(Sphere(Vec3f(-1.0, -1.5, -12), 2, glass));
spheres.push_back(Sphere(Vec3f( 1.5, -0.5, -18), 3, red_rubber));
spheres.push_back(Sphere(Vec3f( 7, 5, -18), 4, mirror));
std::vector<Light> lights;
lights.push_back(Light(Vec3f(-20, 20, 20), 1.5));
lights.push_back(Light(Vec3f( 30, 50, -25), 1.8));
lights.push_back(Light(Vec3f( 30, 20, 30), 1.7));
render(spheres, lights);
return 0;
}