DDA Algorithm

#include <GL/gl.h>
#include <GL/glut.h>
void display(void)
{
/* clear all pixels */
glClear (GL_COLOR_BUFFER_BIT);
/* draw white polygon (rectangle) with corners at
* (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)
*/
// Lab3 Task: Draw a line with edndpoints (100, 130) and (355, 450)

glColor3f (1.0, 0.25, 1.0);

int x1=100, y1=130, x2=355, y2=450;

float dy,dx,step,x,y,k,Xin,Yin;
dx=x2-x1;
dy=y2-y1;


if(abs(dx)> abs(dy))
{
step = abs(dx);
}
else
step = abs(dy);

Xin = dx/step;
Yin = dy/step;

x= x1;
y=y1;
glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();

for (k=1 ;k<=step;k++)
{
x= x + Xin;
y= y + Yin;

glBegin(GL_POINTS);
glVertex2i(x,y);
glEnd();
}

/* don't wait!
* start processing buffered OpenGL routines
*/
glFlush ();
}
void init (void)
{
/* select clearing (background) color */
glClearColor (0.0, 0.0, 0.0, 0.0);
/* initialize viewing values */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
gluOrtho2D(0,600,0,600);        //fix the windows size
}
/*
* Declare initial window size, position, and display mode
* (single buffer and RGBA). Open window with "hello"
* in its title bar. Call initialization routines.
* Register callback function to display graphics.
* Enter main loop and process events.
*/
int main(int argc, char** argv)
{

glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize (1000, 1000);
glutInitWindowPosition (50, 50);
glutCreateWindow ("172-15-9804");
init ();
glutDisplayFunc(display);
glutMainLoop();
return 0; /* ISO C requires main to return int. */
}