tinyraytracer/tinyraytracer.cpp
Dmitry V. Sokolov 9a728fff2b diffuse lighting
2019-01-20 12:16:45 +01:00

116 lines
3.6 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 Vec3f &color) : diffuse_color(color) {}
Material() : diffuse_color() {}
Vec3f diffuse_color;
};
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;
}
};
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;
}
}
return spheres_dist<1000;
}
Vec3f cast_ray(const Vec3f &orig, const Vec3f &dir, const std::vector<Sphere> &spheres, const std::vector<Light> &lights) {
Vec3f point, N;
Material material;
if (!scene_intersect(orig, dir, spheres, point, N, material)) {
return Vec3f(0.2, 0.7, 0.8); // background color
}
float diffuse_light_intensity = 0;
for (size_t i=0; i<lights.size(); i++) {
Vec3f light_dir = (lights[i].position - point).normalize();
diffuse_light_intensity += lights[i].intensity * std::max(0.f, light_dir*N);
}
return material.diffuse_color * diffuse_light_intensity;
}
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) {
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(Vec3f(0.4, 0.4, 0.3));
Material red_rubber(Vec3f(0.3, 0.1, 0.1));
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, red_rubber));
spheres.push_back(Sphere(Vec3f( 1.5, -0.5, -18), 3, red_rubber));
spheres.push_back(Sphere(Vec3f( 7, 5, -18), 4, ivory));
std::vector<Light> lights;
lights.push_back(Light(Vec3f(-20, 20, 20), 1.5));
render(spheres, lights);
return 0;
}