/*
 * torus.java
 * This program demonstrates the creation of a display list.
 */

import java.lang.Math;

import jgl.GL;
import jgl.GLApplet;

public class torus extends GLApplet {

    private int theTorus;

    /* Draw a torus */
    private void torus (int numc, int numt) {
	int i, j, k;
	double s, t, x, y, z, twopi;

	twopi = 2 * Math.PI;
	for (i = 0; i < numc; i++) {
	    myGL.glBegin (GL.GL_QUAD_STRIP);
	    for (j = 0; j <= numt; j++) {
		for (k = 1; k >= 0; k--) {
		    s = (i + k) % numc + 0.5;
		    t = j % numt;

		    x = (1+.1*Math.cos(s*twopi/numc))*Math.cos(t*twopi/numt);
		    y = (1+.1*Math.cos(s*twopi/numc))*Math.sin(t*twopi/numt);
		    z = .1 * Math.sin(s * twopi / numc);
		    myGL.glVertex3f((float)x, (float)y, (float)z);
		}
	    }
	    myGL.glEnd();
	}
    }

    /* Create display list with Torus and initialize state */
    private void myinit () {
	theTorus = myGL.glGenLists (1);
	myGL.glNewList (theTorus, GL.GL_COMPILE);
	torus (8, 25);
	myGL.glEndList ();

	myGL.glShadeModel (GL.GL_FLAT);
    	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
    }

    /* Clear window and draw torus */
    public void display () {
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT);
	myGL.glColor3f (1.0f, 1.0f, 1.0f);
	myGL.glCallList (theTorus);
	myGL.glFlush ();
    }

    /* Handle window resize */
    public void myReshape (int w, int h) {
	myGL.glViewport (0, 0, w, h);
	myGL.glMatrixMode (GL.GL_PROJECTION);
	myGL.glLoadIdentity ();
	myGLU.gluPerspective (30.0, (double)w/(double)h, 1.0, 100.0);
	myGL.glMatrixMode (GL.GL_MODELVIEW);
	myGL.glLoadIdentity ();
	myGLU.gluLookAt (0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
    }

    /* Rotate about x-axis when "x" typed; rotate about y-axis
       when "y" typed; "i" returns torus to original view */
    /* ARGSUSED1 */
    public void keyboard (char key, int x, int y) {
	switch (key) {
	    case 'x':
	    case 'X':
		myGL.glRotatef (30.0f, 1.0f, 0.0f, 0.0f);
		myUT.glutPostRedisplay ();
		break;
	    case 'y':
	    case 'Y':
		myGL.glRotatef (30.0f, 0.0f, 1.0f, 0.0f);
		myUT.glutPostRedisplay ();
		break;
	    case 'i':
	    case 'I':
		myGL.glLoadIdentity ();
		myGLU.gluLookAt (0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
		myUT.glutPostRedisplay ();
		break;
	    default:
		break;
	}
    }

    public void init () {
	myUT.glutInitWindowSize (200, 200);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutDisplayFunc ("display");
	myUT.glutReshapeFunc ("myReshape");
	myUT.glutKeyboardFunc ("keyboard");
	myUT.glutMainLoop ();
    }

}