#include <GL/freeglut.h>
#include <GL/glu.h>
#include <iostream>
 
int posx=0, posy=0;
 
void resize(int width, int height)
{
    glViewport(0, 0, width, height);
 
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-50,50,-50,50,-10,10);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
 
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
}
 
 
//---------------------------------------------------------//
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	glBegin(GL_LINES);
	 glColor3f(1.0f,1.0f,1.0f);
		glVertex3f( -50.0f, 0.0f,0.0f);
		glVertex3f(50.0f, 0.0f,0.0f);
	 glColor3f(1.0f,1.0f,1.0f);
		glVertex3f( 0.0f, -50.0f,0.0f);
		glVertex3f(0.0f, 50.0f,0.0f);
	glEnd();
 
//----------------1º  TRIANGULO----------------//   
  glPushMatrix();
	glTranslatef(posx, posy, 0);
    glColor3f(1,0,0); 
	glutSolidSphere(5, 20, 2);
  glEnd();
  glPopMatrix();	
 
    glutSwapBuffers();
}
//---------------------------------------------------//
 
void key(unsigned char key, int x, int y)
{
    switch (key)
    {
        case 27 :
            exit(0);
            break;
        default:
            break;
    }
 
    glutPostRedisplay();
}
 
 
void tecladoEspecial(int tecla, int x, int y) {
switch(tecla) {
   case GLUT_KEY_UP : posy++;break;
   case GLUT_KEY_DOWN : posy--;break;
   case GLUT_KEY_RIGHT : posx++;break;
   case GLUT_KEY_LEFT : posx--;break;
}
glutPostRedisplay();
}
 
 
 
void idle()
{
    glutPostRedisplay();
}
 
int main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(10,10);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("Transformacion 1");
    glutReshapeFunc(resize);
    glutDisplayFunc(display);
    glutKeyboardFunc(key);
    glutSpecialFunc(tecladoEspecial);
 
    glutIdleFunc(idle);
 
    glutMainLoop();
	return 0;
}