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main.cpp
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#include <iostream>
#include <string>
#include <fstream>
#include <cfloat>
#include <random>
#include <chrono>
#include "vec3.hpp"
#include "ray.hpp"
#include "hitable.hpp"
#include "hitable_list.hpp"
#include "sphere.hpp"
#include "camera.hpp"
#include "lambertian.hpp"
#include "metal.hpp"
#include "dielectric.hpp"
using namespace std;
vec3 random_in_unit_sphere()
{
vec3 p;
long long seed = chrono::high_resolution_clock::now().time_since_epoch().count();
std::default_random_engine rand_gen(static_cast<unsigned int>(seed));
std::uniform_real_distribution<> rand_dist(0.0, 1.0);
do {
p = 2.0 * vec3{
rand_dist(rand_gen),
rand_dist(rand_gen),
rand_dist(rand_gen)
} - vec3{1.0, 1.0, 1.0};
} while (p.squared_length() >= 1.0);
return p;
}
vec3 color(const ray& r, std::shared_ptr<hitable> world, int depth)
{
hit_record rec;
if (world->hit(r, 0.001, DBL_MAX, rec)) {
ray scattered;
vec3 attenuation;
if (depth < 50 &&
rec.mat_ptr->scatter(r, rec, attenuation, scattered)) {
return attenuation * color(scattered, world, depth + 1);
}
else {
return vec3();
}
}
else {
vec3 unit_direction = unit_vector(r.direction());
double t = 0.5 * (unit_direction.y() + 1.0);
return (1.0 - t) * vec3{1.0, 1.0, 1.0} + t * vec3{0.5, 0.7, 1.0};
}
}
std::vector<hitable_ptr> random_scene() {
auto list = std::vector<hitable_ptr>();
// hitable **list = new hitable *[n+1];
/*定义一个包含n+1个元素的数组，数组的每个元素是指向hitable对象的指针。然后将数组的指针赋值给list。所以，list是指针的指针。*/
list.push_back(std::make_shared<sphere>(vec3(0,-1000,0), 1000, std::make_shared<lambertian>(vec3(0.5, 0.5, 0.5))));
/*先创建一个中心在（0，-1000，0）半径为1000的超大漫射球，将其指针保存在list的第一个元素中。*/
int i = 1;
for (int a = -11; a < 11; a++) {
for (int b = -11; b < 11; b++) {
/*两个for循环中会产生（11+11）*(11+11)=484个随机小球*/
float choose_mat = (rand()%(100)/(float)(100));
/*产生一个（0，1）的随机数，作为设置小球材料的阀值*/
vec3 center(a+0.9*(rand()%(100)/(float)(100)), 0.2,
b+0.9*(rand()%(100)/(float)(100)));
/*” a+0.9*(rand()%(100)/(float)(100))”配合[-11,11]产生（-11，11）之间的随机数，而不是[-11,11)之间的22个整数。使得球心的x,z坐标是（-11，11）之间的随机数*/
if ((center-vec3(4,0.2,0)).length() > 0.9) {
/*避免小球的位置和最前面的大球的位置太靠近*/
if (choose_mat < 0.8) { //diffuse
/*材料阀值小于0.8，则设置为漫反射球，漫反射球的衰减系数x,y,z都是（0，1）之间的随机数的平方*/
list.push_back( std::make_shared<sphere>(center, 0.2,
std::make_shared<lambertian>(vec3(
(rand()%(100)/(float)(100))*(rand()%(100)/(float)(100)),
(rand()%(100)/(float)(100))*(rand()%(100)/(float)(100)),
(rand()%(100)/(float)(100))*(rand()%(100)/(float)(100))))));
}
else if (choose_mat < 0.95) {
/*材料阀值大于等于0.8小于0.95，则设置为镜面反射球，镜面反射球的衰减系数x,y,z及模糊系数都是（0，1）之间的随机数加一再除以2*/
list.push_back( std::make_shared<sphere>(center, 0.2,
std::make_shared<metal>(vec3(0.5*(1+(rand()%(100)/(float)(100))),
0.5*(1+(rand()%(100)/(float)(100))),
0.5*(1+(rand()%(100)/(float)(100)))),
0.5*(1+(rand()%(100)/(float)(100))))));
}
else {
/*材料阀值大于等于0.95，则设置为介质球*/
list.push_back( std::make_shared<sphere>(center, 0.2, std::make_shared<dielectric>(1.5)));
}
}
}
}
list.push_back( std::make_shared<sphere>(vec3(0, 1, 0), 1.0, std::make_shared<dielectric>(1.5)));
list.push_back( std::make_shared<sphere>(vec3(-4, 1, 0), 1.0, std::make_shared<lambertian>(vec3(0.4, 0.2, 0.1))));
list.push_back( std::make_shared<sphere>(vec3(4, 1, 0), 1.0, std::make_shared<metal>(vec3(0.7, 0.6, 0.5), 0.0)));
return list;
}
int main() {
auto filename = "ch12.ppm";
std::ofstream out(filename);
cout << "output image: " << filename << endl;
vec3 lookfrom(13,2,3);
vec3 lookat(0, 0, 0);
double aperture = 0.0;
double dist_to_focus = (lookfrom - lookat).length();
camera cam{
lookfrom,
lookat,
vec3(0, 1, 0),
20,
double(16)/double(9),
aperture,
0.7*dist_to_focus
};
// auto list = std::vector<hitable_ptr>();
//
// list.push_back(std::make_shared<sphere>(vec3{0, 0, -1}, 0.5, std::make_shared<lambertian>(vec3{0.1, 0.2, 0.5})));
// list.push_back(std::make_shared<sphere>(vec3{0, -100.5, -1}, 100, std::make_shared<lambertian>(vec3{0.8, 0.8, 0.0})));
// list.push_back(std::make_shared<sphere>(vec3{1, 0, -1}, 0.5, std::make_shared<metal>(vec3{0.8, 0.6, 0.2})));
// list.push_back(std::make_shared<sphere>(vec3{-1, 0, -1}, 0.5, std::make_shared<dielectric>(1.5)));
// list.push_back(std::make_shared<sphere>(vec3{-1, 0, -1}, -0.45, std::make_shared<dielectric>(1.5)));
auto list = random_scene();
auto world = std::make_shared<hitable_list>(list, 484);
int nx = 200;
int ny = 100;
int ns = 100;
out << "P3\n" << nx << " " << ny << "\n255\n";
std::default_random_engine rand_gen(1);
std::uniform_real_distribution<> rand_dist(0, 1.0);
for (int j = ny - 1; j >= 0; j--) {
for (int i = 0; i < nx; i++) {
vec3 col{0, 0, 0};
for (int s = 0; s < ns; s++) {
double u = double(i + rand_dist(rand_gen)) / double(nx);
double v = double(j + rand_dist(rand_gen)) / double(ny);
ray r = cam.get_ray(u, v);
vec3 p = r.point_at_parameter(2.0);
col += color(r, world, 0);
}
col /= double(ns);
col = vec3{sqrt(col[0]), sqrt(col[1]), sqrt(col[2])};
int ir = int(255.99 * col[0]);
int ig = int(255.99 * col[1]);
int ib = int(255.99 * col[2]);
out << ir << " " << ig << " " << ib << "\n";
}
}
out.close();
return EXIT_SUCCESS;
}