#include <GL/glut.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>

float round_value(float v) {
	return floor(v + 0.5);
}

void LineDDA(void) {
	//set line coordinates
	double X1, Y1, X2, Y2;
	X1 = Y1 = 50;
	X2 = 300;
	Y2 = 200;

	double dx=(X2-X1), dy = (Y2-Y1), steps;
	float xInc, yInc, x=X1, y=Y1;
	
	/* Find out whether to increment x or y */
	steps=(abs(dx)>abs(dy)) ? (abs(dx)) : (abs(dy));
	xInc=dx/(float)steps;
	yInc=dy/(float)steps;

	/* Clears buffers to preset values */
	glClear(GL_COLOR_BUFFER_BIT);

	/* Plot the points */
	glBegin(GL_POINTS);

	/* Plot the first point */
	glVertex2d(x,y);
	int k;

	/* For every step, find an intermediate vertex */
	for(k=0; k<steps; k++)  {
		x += xInc;
		y += yInc;

		glVertex2d(round_value(x), round_value(y));
	}
	glEnd();

	glFlush();
}

int main(int argc,char *argv[]) {
	glutInit(&argc,argv);                   //prepare glut
	glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);       //set the display mode
	glutInitWindowSize (500, 500);          //the size of the program window
	glutInitWindowPosition (100, 100);      //initial position for the window
	glutCreateWindow ("CS334-lab11");  //create window with a title

	glClearColor(0,0,0,0.0);          //background color
	glMatrixMode (GL_PROJECTION);           //2d envyronment
	gluOrtho2D (0, 350.0, 0, 250.0);   //canvas area (LRBT)

	glutDisplayFunc(LineDDA);               //show thee actual program
	glutMainLoop();

	return EXIT_SUCCESS;                    //exit the program
}