First commit

main.cpp

@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdint.h>
+
+#include "vec3.hpp"
+#include "color.hpp"
+#include "ray.hpp"
+
+color ray_color(const ray& r);
+double hit_sphere(const point3& center, double radius, const ray& r);
+
+color ray_color(const ray& r)
+{
+    double t = hit_sphere(point3(0,0,-1), 0.5, r);
+    if (t > 0.0)
+    {
+        vec3 N = normalize(r.at(t) - vec3(0,0,-1));
+        return 0.5*color(N.x+1, N.y+1, N.z+1);
+    }
+    vec3 unit_direction = normalize(r.direction);
+    t = 0.5*(unit_direction.y + 1.0);
+    
+    return (1-t) * color(1,1,1) + t*color(0.5, 0.7, 1.0);
+}
+
+double hit_sphere(const point3& center, double radius, const ray& r)
+{
+    vec3 oc = r.origin - center;
+    double a = dot(r.direction, r.direction);
+    double b = 2.0 * dot(oc, r.direction);
+    double c = dot(oc,oc) - radius*radius;
+    double discriminant = b*b - 4*a*c;
+    if (discriminant < 0)
+        return -1;
+    else
+        return (-b - sqrt(discriminant)) / (2.0*a);
+}
+
+int main()
+{
+    // Image
+    double aspect_ratio = 16.0 / 9;
+    const int32_t image_width = 400;
+    const int32_t image_height = (int32_t) (image_width / aspect_ratio);
+
+    // Camera
+    double viewport_height = 2.0;
+    double viewport_width = aspect_ratio * viewport_height;
+    double focal_length = 1.0;
+
+    point3 origin = point3(0,0,0);
+    vec3 horizontal = vec3(viewport_width, 0, 0);
+    vec3 vertical = vec3(0, viewport_height, 0);
+    vec3 lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length);
+
+    // Render
+    printf("P3\n%d %d\n255\n", image_width, image_height);
+
+    for (int32_t j = image_height - 1; j >= 0; --j)
+    {
+        fprintf(stderr, "\rScanlines remaining: %d ", j);
+        fflush(stderr);
+        for (int32_t i = 0; i < image_width; ++i)
+        {
+            double u = (double)i / (image_width-1);
+            double v = (double)j / (image_height-1);            
+            ray r = ray(origin, lower_left_corner + u*horizontal + v*vertical - origin);            
+            color pixel_color = ray_color(r);
+            
+            write_color(stdout, pixel_color);
+        }        
+    }
+    fprintf(stderr, "\nDone\n");
+}