camera.h

#pragma once
#define M_PI 3.14159265358979323846
#include "ray.h"
//#include <cmath>
#include "material.h"

vec3 random_in_unit_disk() {
	vec3 p;
	do {
		p = 2.0*vec3(uni_dist(mt), uni_dist(mt), 0) - vec3(1, 1, 0);
	} while (dot(p, p) >= 1.0);
	return p;
}

class camera
{
public:
	//camera() {
	//	lower_left_corner = vec3(-2.0, -1.0, -1.0);
	//	horizontal = vec3(4.0, 0.0, 0.0);
	//	vertical = vec3(0.0, 2.0, 0.0);
	//	origin = vec3(0.0, 0.0, 0.0);
	//}
	//ray get_ray(float u, float v) { return ray(origin, lower_left_corner + u * horizontal + v * vertical - origin); }
	camera(vec3 lookfrom, vec3 lookat, vec3 vup, float vfov, float aspect, float aperature, float focus_dist) {
		lens_radius = aperature / 2;
		float theta = vfov * M_PI / 180;
		float half_height = tan(theta / 2);
		float half_width = aspect * half_height;
		origin = lookfrom;
		w = unit_vector(lookfrom - lookat);
		u = unit_vector(cross(vup, w));
		v = cross(w, u);
		lower_left_corner = origin - half_width * focus_dist * u - half_height * focus_dist * v - focus_dist * w;
		horizontal = 2 * half_width*focus_dist*u;
		vertical = 2 * half_height*focus_dist*v;
		
	}
	ray get_ray(float s, float t) {
		vec3 rd = lens_radius * random_in_unit_disk();
		vec3 offset = u * rd.x() + v * rd.y();
		return ray(origin + offset, lower_left_corner + s*horizontal + t*vertical - origin - offset);
	}

	vec3 origin;
	vec3 lower_left_corner;
	vec3 horizontal;
	vec3 vertical;
	vec3 u, v, w;
	float lens_radius;
};