74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
#include <stdio.h>
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#include <stdint.h>
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#include "vec3.hpp"
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#include "color.hpp"
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#include "ray.hpp"
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color ray_color(const ray& r);
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double hit_sphere(const point3& center, double radius, const ray& r);
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color ray_color(const ray& r)
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{
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double t = hit_sphere(point3(0,0,-1), 0.5, r);
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if (t > 0.0)
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{
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vec3 N = normalize(r.at(t) - vec3(0,0,-1));
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return 0.5*color(N.x+1, N.y+1, N.z+1);
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}
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vec3 unit_direction = normalize(r.direction);
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t = 0.5*(unit_direction.y + 1.0);
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return (1-t) * color(1,1,1) + t*color(0.5, 0.7, 1.0);
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}
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double hit_sphere(const point3& center, double radius, const ray& r)
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{
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vec3 oc = r.origin - center;
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double a = r.direction.length_squared();
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double half_b = dot(oc, r.direction);
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double c = oc.length_squared() - radius*radius;
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double discriminant = half_b*half_b - a*c;
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if (discriminant < 0)
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return -1;
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else
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return (-half_b - sqrt(discriminant)) / a;
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}
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int main()
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{
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// Image
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double aspect_ratio = 16.0 / 9;
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const int32_t image_width = 400;
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const int32_t image_height = (int32_t) (image_width / aspect_ratio);
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// Camera
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double viewport_height = 2.0;
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double viewport_width = aspect_ratio * viewport_height;
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double focal_length = 1.0;
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point3 origin = point3(0,0,0);
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vec3 horizontal = vec3(viewport_width, 0, 0);
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vec3 vertical = vec3(0, viewport_height, 0);
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vec3 lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length);
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// Render
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printf("P3\n%d %d\n255\n", image_width, image_height);
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for (int32_t j = image_height - 1; j >= 0; --j)
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{
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fprintf(stderr, "\rScanlines remaining: %d ", j);
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fflush(stderr);
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for (int32_t i = 0; i < image_width; ++i)
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{
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double u = (double)i / (image_width-1);
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double v = (double)j / (image_height-1);
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ray r = ray(origin, lower_left_corner + u*horizontal + v*vertical - origin);
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color pixel_color = ray_color(r);
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write_color(stdout, pixel_color);
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}
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}
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fprintf(stderr, "\nDone\n");
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}
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