#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>

double x1,x2;

void display(void)
{
   
   glClear(GL_COLOR_BUFFER_BIT);
   glColor3f(0.0,0.0,0.0);
   
   glLoadIdentity();
   
//   glTranslatef( x1, 0.0, 0.0);

   glColor3f( 1.0, 0.0, 0.0);
   glBegin(GL_QUADS);
//      printf("\nx1: %f\n",x1);
      glVertex3f( 0.25+x1, 0.25+x1, 0.0);
      glVertex3f( 0.75+x1, 0.25+x1, 0.0);
      glVertex3f( 0.75+x1, 0.75+x1, 0.0);
      glVertex3f( 0.25+x1, 0.75+x1, 0.0);
//      glVertex3f( 0.00, 0.00, 0.0);
//      glVertex3f( 0.50, 0.00, 0.0);
//      glVertex3f( 0.50, 0.50, 0.0);
//      glVertex3f( 0.00, 0.50, 0.0);
   glEnd();

//   glTranslatef( 2*x2, 0.0, 0.0);

   glColor3f( 0.0, 1.0, 0.0);
   glBegin(GL_QUADS);
//      printf("\nx2: %f\n",x1);
//      glVertex3f( 0.25, 0.25, 0.0);
//      glVertex3f( 0.75, 0.25, 0.0);
//      glVertex3f( 0.75, 0.75, 0.0);
//      glVertex3f( 0.25, 0.75, 0.0);
      glVertex3f( 0.25+x2, 0.25+x2, 0.0);
      glVertex3f( 0.75+x2, 0.25+x2, 0.0);
      glVertex3f( 0.75+x2, 0.75+x2, 0.0);
      glVertex3f( 0.25+x2, 0.75+x2, 0.0);
      glEnd();

   glFlush();
   glutSwapBuffers();

   glutPostRedisplay();

   x1-=.0001;
   x2+=.0001;
}

int main(int argc,char* argv[])
{
   printf("1\n");
   glutInit(&argc,argv);
   glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
   glutInitWindowSize(400,400);
   glutInitWindowPosition(100,50);
   glutCreateWindow("2d collision detection");
   
   printf("2/\n");

   glClearColor(1.0,1.0,1.0,0.0);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(0.0,1.0,0.0,1.0,-1.0,1.0); // left, right, bottom, top, front, back
   
   printf("3\n");

   x1=0.0;
   x2=-1.0;
   int k;
   for(k=0;k<20;k++)
   {
   printf("4\n");
   glutDisplayFunc(display);
   printf("5\n");
   }

   printf("6\n");

   glutMainLoop();
   

   return 0;
}