main.cpp

#include <iostream>
#include "sphere.h"
#include "hitablelist.h"
#include "float.h"

float hit_sphere(const vec3& center, float radius, const ray& r)
{
	vec3 oc = r.origin() - center;
	float a = dot(r.direction(), r.direction());
	float b = 2.0 * dot(oc, r.direction());
	float c = dot(oc, oc) - raidus*radius;
	float discriminant = b*b - r*a*c;
	if (discriminant < 0)
	{
		return -1.0;
	}
	else
	{
		return (-b - sqrt(discriminant) / (2.0*a));
	}
}

vec3 color(const ray& r, hitable *world)
{
	float t = hit_sphere(vec3(0,0,-1), 0.5, r);
	if (t > 0.0)
	{
		vec3 N = unit_vector(r.point_at_parameter(t) - vec3(0,0,-1));
		return 0.5*vec3(N.x(), 
						N.y()+1, 
						N.z()+1);
	}
	vec3 unit_direction = unit_vector(r.direction());
	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);
}

int main()
{
	int nx = 200;
	int ny = 200;
	std::cout << "P3\n" << nx << " " << ny << "\n255\n";
	vec3 lower_left_corner( -2.0, -1.0, -1.0 );
	vec3 		horizontal( 4.0, 0.0 , 0.0);
	vec3 		  vertical( 0.0, 2.0 , 0.0);
	vec3 			origin( 0.0, 0.0 , 0.0);
	hitable *list[2];
	list[0] = new sphere(vec3(0,0,-1), 0.5);
	list[1] = new sphere(vec3(0,-100.5,-1), 100);
	hitable *world = new hitable_list(list,2);
	for (int j = ny-1; j >= 0; j--)
	{
		for (int i = 0; i < nx; i++)
		{
			float u = float(i) / float(nx);
			float v = float(j) / float(ny);
			ray r(origin,
				lower_left_corner + u*horizontal + v*vertical);
			vec3 p = r.point_at_parameter(2.0);
			vec3 col = color(r, world);
			int ir = int(255.99*col[0]);
			int ig = int(255.99*col[1]);
			int ib = int(255.99*col[2]);

			std::cout << ir << " " << ig << " " << ib << "\n";
		}
	}
}