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#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
}