#include <vector>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <math.h>


class camera {



//need variables for the position, lookat direction, the aspect ratio and FOV
private:

	int height;
	int width;
	float fov;
	vec3 up;


public:

	vec3 position;
	vec3 lookat;
	int totalRays;

	//
	void setCamera(vec3 pos, vec3 look, int w, int h, float fo)
	{
		position = pos;
		lookat = look;
		fov = fo;
	
		height = h;
		width = w;

		totalRays = h*w;

		up.x = 0; up.y = 1; up.z = 0;
	}



	void setCamera(vec3 pos, vec3 look, int w, int h, vec3 upVec, float fo)
	{
		position = pos;
		lookat = look;
		fov = fo;
	
		height = h;
		width = w;

		totalRays = h*w;

		up.x = upVec.x; up.y = upVec.y; up.z = upVec.z;
	}
	vec3 calculateRay(int i, int j)
	{

		double radians = 3.14*(fov/180.0);
		double theta = radians/2.0f;

		

		double y = sin(theta);
		double x = cos(theta);

		//calculate the width and height of the virtual image plane which is 1 unit away from the camera's origin point		
	//	double W = 2.0*(y/x);
	//	double H = W*((double)height/(double)width);

		double H = 2.0*(y/x);
		double W = H*((double)width/(double)height);

		//now find the 3D points in space corresponding to the pixels on the image plane
		//the image plane starts distance unit 1 from the origin down the view ray
		lookat.normalize();
		vec3 imageCenter(position.x + lookat.x, position.y + lookat.y, position.z + lookat.z);
		//now get the horizontal direction along the width of our virtual image
		up.normalize();
		vec3 horizontalDirection = lookat.crossProduct(up);
		horizontalDirection.normalize();
		//now get the vertical direction for our virtual image plane
		vec3 verticalDirection = lookat.crossProduct(horizontalDirection);
		verticalDirection.normalize();
		//now get the upper left point of our virtual image plane
		vec3 upperLeft( imageCenter.x + horizontalDirection.x*(W/2.0) + verticalDirection.x*(H/2.0),
						imageCenter.y + horizontalDirection.y*(W/2.0) + verticalDirection.y*(H/2.0) ,
						imageCenter.z + horizontalDirection.z*(W/2.0) + verticalDirection.z*(H/2.0) );

		double xDisp = -W/(double)width;
		double yDisp = -H/(double)height;


		vec3 point( upperLeft.x + horizontalDirection.x*xDisp*i + verticalDirection.x*yDisp*j, 
					upperLeft.y + horizontalDirection.y*xDisp*i + verticalDirection.y*yDisp*j,
					upperLeft.z + horizontalDirection.z*xDisp*i + verticalDirection.z*yDisp*j );

		//get the direction from the eye point into the scene
		vec3 viewVec(point.x - position.x, point.y - position.y, point.z - position.z);
		viewVec.normalize();

		return viewVec;
	}

	vec3 getPosition()
	{
		return position;
	}



};