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Adding a sphere

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This commit is contained in:
Armin Friedl 2022-07-18 15:32:51 +02:00
parent a12fcfbe7b
commit ba40f3736c
1 changed files with 30 additions and 9 deletions
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39
rtiww/src/main.cpp
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@ -4,28 +4,49 @@
#include <iostream>
color ray_color(const ray& r) {
double hit_sphere(const point3 &center, double radius, const ray &r) {
vec3 oc = r.origin() - center;
auto a = dot(r.direction(), r.direction());
auto b = 2.0 * dot(oc, r.direction());
auto c = dot(oc, oc) - radius * radius;
auto discriminant = b * b - 4 * a * c;
if (discriminant < 0) {
return -1.0;
} else {
return (-b - sqrt(discriminant)) / (2.0*a);
}
}
color ray_color(const ray &r) {
auto t = hit_sphere(point3(0,0,-1), 0.5, r);
if(t > 0.0) {
vec3 N = unit_vector(r.at(t) - vec3(0,0,-1));
return 0.5*color(N.x()+1, N.y()+1, N.z()+1);
}
vec3 unit_direction = unit_vector(r.direction());
auto t = 0.5 * (unit_direction.y() + 1.0);
return (1.0-t)*color(1.0, 1.0, 1.0) + t*color(0.5, 0.7, 1.0);
t = 0.5*(unit_direction.y() + 1.0);
return (1.0 - t) * color(1.0, 1.0, 1.0) + t * color(0.5, 0.7, 1.0);
}
int main() {
// Image
const auto aspect_ratio = 16.0/9.0;
const auto aspect_ratio = 16.0 / 9.0;
const int image_width = 400;
const int image_height = static_cast<int>(image_width / aspect_ratio);
// Camera
auto viewport_height = 2.0;
auto viewport_width = aspect_ratio*viewport_height;
auto viewport_width = aspect_ratio * viewport_height;
auto focal_length = 1.0;
auto origin = point3(0, 0, 0);
auto horizontal = vec3(viewport_width, 0, 0);
auto vertical = vec3(0, viewport_height, 0);
auto lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length);
auto lower_left_corner = origin - horizontal / 2 - vertical / 2 - vec3(0, 0, focal_length);
// Render
std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
@ -33,10 +54,10 @@ int main() {
for (int j = image_height - 1; j >= 0; --j) {
std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
for (int i = 0; i < image_width; ++i) {
auto u = double(i)/(image_width-1);
auto v = double(j) / (image_height-1);
auto u = double(i) / (image_width - 1);
auto v = double(j) / (image_height - 1);
ray r(origin, lower_left_corner + u*horizontal + v*vertical - origin);
ray r(origin, lower_left_corner + u * horizontal + v * vertical - origin);
color pixel_color = ray_color(r);
write_color(std::cout, pixel_color);
}