// This program demonstrates more about colors and loops and functions

#include <iostream>
#include <cstdlib>
#include "graphics.h"

using namespace std;

const int WINDOW_SIZE = 400;	//The size of the window that we use
const int MAX_PIXEL_X = WINDOW_SIZE - 1; //Maximum x value in pixel coordinates
const int MAX_PIXEL_Y = WINDOW_SIZE - 1; //Maximum y value in pixel coordinates
const double MAX_CART_X = 5; //Maximum x value in cartitian coordinates
const double MAX_CART_Y = 5; //Maximum y value in cartitian coordinates
const int MIN_PIXEL_X = 0; //Minimum x value in pixel coordinates
const int MIN_PIXEL_Y = 0; //Minimum y value in pixel coordinates
const double MIN_CART_X = 0; //Minimum x value in cartitian coordinates
const double MIN_CART_Y = 0; //Minimum y value in cartitian coordinates
const int PIXEL_WIDTH = MAX_PIXEL_X - MIN_PIXEL_X + 1; //Pixel Width
const double CART_WIDTH = MAX_CART_X - MIN_CART_X; //Cartitian Width
const int PIXEL_HEIGHT = MAX_PIXEL_Y - MIN_PIXEL_Y + 1; //Pixel Height
const double CART_HEIGHT = MAX_CART_Y - MIN_CART_Y; //Cartitian Height

//Function prototypes
double x_cart_conversion(int px);
double y_cart_conversion(int py);
int cart_color(double cx, double cy);

/////////////////////////////////////////////////////////////////////////
int main()
{
	int pixel_x, pixel_y; //Coordinate variables
	double cart_x, cart_y; //Cartitian coordinate variables
	int color; //variable to hold color
	initwindow(WINDOW_SIZE, WINDOW_SIZE, "Additive Colors");

	for(pixel_x = 0; pixel_x < WINDOW_SIZE; ++pixel_x)
	{
		for(pixel_y = 0; pixel_y < WINDOW_SIZE; ++pixel_y)
		{
			//Change pixel_x to Cartitian coordinate
			cart_x = x_cart_conversion(pixel_x);
			//Change pixel_y to Cartitian coordinate
			cart_y = y_cart_conversion(pixel_y);
			//Choose color based on those coordinate
			color = cart_color(cart_x, cart_y);
			putpixel(pixel_x, pixel_y, color);
		}
	}

	getch();

    return EXIT_SUCCESS;
}
/////////////////////////////////////////////////////////////////////////


/////////////////////////////////////////////////////////////////////////
double x_cart_conversion(int px) //Note: No semicolon here!
{
	double ans;
	ans = CART_WIDTH/PIXEL_WIDTH * px + MIN_CART_X;

	return ans;
}
/////////////////////////////////////////////////////////////////////////


/////////////////////////////////////////////////////////////////////////
double y_cart_conversion(int py) //Note: No semicolon here!
{
	double ans;
	ans = -CART_HEIGHT/PIXEL_HEIGHT * py + MAX_CART_X;

	return ans;
}
/////////////////////////////////////////////////////////////////////////


/////////////////////////////////////////////////////////////////////////
int cart_color(double cx, double cy)
{
	if((cx > 2) && (cy < 3))
	{
		return COLOR(255, 0, 0); //This is red
	}
	else
	{
		return COLOR(0, 0, 0); //This is black 
	}
}
/////////////////////////////////////////////////////////////////////////