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main.cc
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main.cc
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// This code generates a PPM (Portable Pixmap) image file that is 256 x 256
// The color values for each pixel are determined based on the pixel's position
// To compile:
// make
// To clean
// make clean
#include "color.h"
#include "ray.h"
#include "vec3.h"
#include <iostream>
color ray_color(const ray& r){
// Calculate the unit direction of the ray
vec3 unit_direction = unit_vector(r.direction());
// Map the y-component of the unit direction to the range [0,1]
auto a = 0.5 * (unit_direction.y() + 1.0);
// Linearly interpolate between white and blue based on the mapped y-component
return (1.0 - a) * color(1.0, 1.0, 1.0) + a * color(0.5, 0.7, 1.0);
}
int main(){
// Image
auto aspect_ratio = 16.0 / 9.0;
int image_width = 400;
// Calculate the image height and ensure that it's at least 1
int image_height = static_cast<int>(image_width / aspect_ratio);
image_height = (image_height < 1) ? 1 : image_height;
// Camera
auto focal_length = 1.0;
auto viewport_height = 2.0;
auto viewport_width = viewport_height * (static_cast<double>(image_width)/image_height);
auto camera_center = point3(0,0,0);
// Calculate the vectors across the horizontal and down the vertical viewport edges
auto viewport_u = vec3(viewport_width, 0, 0);
auto viewport_v = vec3(0, -viewport_height, 0);
// Calculate the horizontal and vertical delta vectors from pixel to pixel
auto pixel_delta_u = viewport_u / image_width;
auto pixel_delta_v = viewport_v / image_height;
// Calculate the location of the upper left pixel
auto viewport_upper_left = camera_center - vec3(0, 0, focal_length) - viewport_u/2 - viewport_v/2;
auto pixel00_loc = viewport_upper_left + 0.5 * (pixel_delta_u + pixel_delta_v);
// Render
std::cout << "P3\n" << image_width << " " << image_height << "\n255\n";
// Trace ray through each pixel of the image, compute the color along each ray, and output
// resulting colors to the output stream
for(int j = 0; j < image_height; ++j){
std::clog << "\rScanlines remaining: " << (image_height - j) << ' ' << std::flush;
for(int i = 0; i < image_width; ++i){
// Calculate the world-space position of the center of the current pixel
auto pixel_center = pixel00_loc + (i * pixel_delta_u) + (j * pixel_delta_v);
// Calculate the direction of the ray from the camera to the pixel
auto ray_direction = pixel_center - camera_center;
// Create a ray with the calculated direction, starting from the camera position
ray r(camera_center, ray_direction);
// Compute the color along the ray using the ray_color function
color pixel_color = ray_color(r);
// Write the color information to the output stream
write_color(std::cout, pixel_color);
}
}
std::clog << "\rDone. \n";
}