/*   mcvillar   */
#include <windows.h>
#include <gl/glut.h>

GLUquadricObj *qobj;

//GLfloat  girax = 0, giray= 0, zoom= 5;  //Ortogonal
GLfloat  girax = 0, giray= 0, zoom= -40;  //Perspectiva
GLboolean showGrid = GL_FALSE;
GLboolean showAxes = GL_TRUE;

/*  ---------------------  Rotacion y Zoom  ---------------------  */

void mover (void)
{
    glTranslated( 0, 0, zoom);
    glRotated( girax, 1.0, 0.0, 0.0);
    glRotated( giray, 0.0, 1.0, 0.0);
}

/* ------------------------  Rejilla y Ejes  --------------------- */

GLvoid Grid (GLvoid)
{
   GLfloat  x,z;
   float long_eje= 10;
   float incremento = 0.5;

	  glColor3f(1.0,0.0,0.0);  
	  glLineWidth(2);
      glBegin(GL_LINES);
         for (x = -long_eje; x<=long_eje; x+= incremento ) {
            glVertex3f (x,0,-long_eje);
            glVertex3f (x,0,long_eje);
          } 
          for (z = -long_eje; z<= long_eje; z+= incremento ) {
             glVertex3f (-long_eje,0,z);
             glVertex3f (long_eje,0,z);
           } 
      glEnd();
}

GLvoid Ejes ( GLvoid)
{
      glColor3f(1.0,1.0,0.0);  /* amarillo */
      glBegin( GL_LINES );
         glVertex3f (0.0,0.0,0.0);
         glVertex3f (11.0,0.0,0.0);
         glVertex3f (0.0,0.0,0.0);
         glVertex3f (0.0,11.0,0.0);
         glVertex3f (0.0,0.0,0.0);
         glVertex3f (0.0,0.0,11.0);
      glEnd();
      glBegin( GL_TRIANGLES );
	     /*  eje x */
         glVertex3f (11.0,0.0,0.0);
         glVertex3f (10.5,0.0,-.50);
         glVertex3f (10.5,0.0,.50);
        /* eje y */
         glVertex3f (0.0,11.0,0.0);
         glVertex3f (-.50,10.5,0.0);
         glVertex3f (.50,10.5,0.0);
		/* eje z*/ 
         glColor3f(1.0,0.0,1.0);  	/* lila */
         glVertex3f (0.0,0.0,11.0);
         glVertex3f (-.50,0.0,10.5);
         glVertex3f (.50,0.0,10.5);
       glEnd();
}

/*  -------------------  Dibuja Escena  ---------------------  */

void dibuja(void)
{ 	
	qobj = gluNewQuadric ();

	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

	glPushMatrix();    
	  mover();
	  if ( showGrid == GL_TRUE ) Grid();   
	  if ( showAxes == GL_TRUE ) Ejes();
      glColor3f(.2,.2,1.);
	  gluQuadricDrawStyle(qobj,GLU_LINE);
	  gluCylinder(qobj,1,1,8,20,20);
   glPopMatrix();

   glutSwapBuffers();
}

/* -----------------  Funciones con Teclas  ---------------  */

void keyboard(unsigned char key, int x, int y) {
  switch(key) {
    case 27:  exit (0); 
              break;  
    case 'i': zoom += 1;
			  break;
    case 'o': zoom -= 1;
			  break;
    case 'g': showGrid = !showGrid;
			  break;
	case 'e': showAxes = !showAxes;
     default: break;
  }
  glutPostRedisplay();
}

void flechas(int key, int x, int y) {
  switch(key) {
    case GLUT_KEY_LEFT:  giray-= 15;
         break;
    case GLUT_KEY_RIGHT: giray+= 15;
         break;
    case GLUT_KEY_UP:   girax -= 15;
	     break;
    case GLUT_KEY_DOWN: girax += 15;
    default:break;
  }
  glutPostRedisplay();
}

/* -----------------------  Reshape  ------------------ */

void reshape(int width, int height)
{
	glClearColor(1.0,1.0,1.0,0.0);
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45, (float)width/height,0,80);
//	glOrtho(-15,15,-15,15,-20,20);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glEnable(GL_DEPTH_TEST);
}

/* -----------------------  main  ------------------ */

int main(int argc, char** argv)
{
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH);
    glutInitWindowPosition(200, 200);
    glutInitWindowSize(640, 640);
    glutInit(&argc, argv);
    glutCreateWindow("Cilindro");

    glutDisplayFunc(dibuja);
    glutReshapeFunc(reshape);
    glutKeyboardFunc(keyboard);
	glutSpecialFunc(flechas);

    glutMainLoop();
    return 0;
}