/*
 *  surface.java
 *  This program draws a NURBS surface in the shape of a 
 *  symmetrical hill.
 */

import java.awt.Frame;
import java.io.IOException;
import java.lang.String;
import java.lang.System;

import jgl.GL;
import jgl.GLU;
import jgl.GLUT;
import jgl.GLCanvas;

import jgl.glu.*;

public class surface extends GLCanvas {

    private float ctlpoints [][][] = new float [4][4][3];
    private boolean showPoints = false;

    private GLUnurbsObj theNurb;

    /*
     *  Initializes the control points of the surface to a small hill.
     *  The control points range from -3 to +3 in x, y, and z
     */
    private void init_surface () {
	int u, v;
	for (u = 0; u < 4; u++) {
	    for (v = 0; v < 4; v++) {
		ctlpoints [u][v][0] = 2.0f * ((float)u - 1.5f);
		ctlpoints [u][v][1] = 2.0f * ((float)v - 1.5f);

		if (((u == 1) || (u == 2)) && ((v == 1) || (v == 2))) {
		    ctlpoints [u][v][2] = 7.0f;
		} else {
		    ctlpoints [u][v][2] = -3.0f;
		}
	    }
	}
    }

    /*
     *  Initialize material property and depth buffer.
     */
    private void myinit () {
	float mat_diffuse[] = { 0.7f, 0.7f, 0.7f, 1.0f };
	float mat_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
	float mat_shininess[] = { 100.0f };

	myGL.glClearColor (0.0f, 0.0f, 0.0f, 1.0f);
	myGL.glMaterialfv (GL.GL_FRONT, GL.GL_DIFFUSE, mat_diffuse);
	myGL.glMaterialfv (GL.GL_FRONT, GL.GL_SPECULAR, mat_specular);
	myGL.glMaterialfv (GL.GL_FRONT, GL.GL_SHININESS, mat_shininess);

	myGL.glEnable (GL.GL_LIGHTING);
	myGL.glEnable (GL.GL_LIGHT0);
	myGL.glDepthFunc (GL.GL_LESS);
	myGL.glEnable (GL.GL_DEPTH_TEST);
	myGL.glEnable (GL.GL_AUTO_NORMAL);
	myGL.glEnable (GL.GL_NORMALIZE);

	init_surface ();

	theNurb = myGLU.gluNewNurbsRenderer ();
	myGLU.gluNurbsProperty (theNurb,GLU.GLU_SAMPLING_TOLERANCE, 25.0f);
	myGLU.gluNurbsProperty (theNurb,GLU.GLU_DISPLAY_MODE,GLU.GLU_FILL);
	
	myGL.glMatrixMode (GL.GL_MODELVIEW);
	myGL.glLoadIdentity ();
	myGL.glTranslatef (0.0f, 0.0f, -5.0f);
    }

    public void display () {
	float knots [] = { 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f };
	int i, j;

	myGL.glClear (GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);

	myGL.glPushMatrix ();
	    myGL.glRotatef (330.0f, 1.0f, 0.0f, 0.0f);
	    myGL.glScalef (0.25f, 0.25f, 0.25f);

	    myGLU.gluBeginSurface (theNurb);
	    myGLU.gluNurbsSurface (theNurb,
		8, knots,
		8, knots,
		4 * 3,
		3,
		ctlpoints,
		4, 4,
		GL.GL_MAP2_VERTEX_3);
	    myGLU.gluEndSurface (theNurb);

	    if(showPoints) {
		myGL.glPointSize (5.0f);
		myGL.glDisable (GL.GL_LIGHTING);
		myGL.glColor3f (1.0f, 1.0f, 0.0f);
		myGL.glBegin (GL.GL_POINTS);
		for (i = 0; i < 4; i++) {
		    for (j = 0; j < 4; j++) {
			myGL.glVertex3f (ctlpoints[i][j][0], ctlpoints[i][j][1], ctlpoints[i][j][2]);
		    }
		}
		myGL.glEnd ();
		myGL.glEnable (GL.GL_LIGHTING);
	    }

	myGL.glPopMatrix ();
	myGL.glFlush ();
    }

    public void myReshape (int w, int h) {
        myGL.glViewport (0, 0, w, h);
        myGL.glMatrixMode (GL.GL_PROJECTION);
        myGL.glLoadIdentity ();
	myGLU.gluPerspective (45.0, (double)w/(double)h, 3.0, 8.0);

        myGL.glMatrixMode (GL.GL_MODELVIEW);
    }

    public void menu (int value) {
	switch (value) {
	    case 0:
		showPoints = false;
		break;
	    case 1:
		showPoints = true;
		break;
	    case 2:
		myGLU.gluNurbsProperty (theNurb, GLU.GLU_DISPLAY_MODE, GLU.GLU_FILL);
		break;
	    case 3:
		myGLU.gluNurbsProperty (theNurb, GLU.GLU_DISPLAY_MODE, GLU.GLU_OUTLINE_POLYGON);
		break;
	}
	myUT.glutPostRedisplay ();
    }

    private boolean down = false;
    private int lastx;

    /* ARGSUSED1 */
    public void motion (int x, int y) {
	if (down) {
	    myGL.glRotatef (lastx - x, 0, 1, 0);
	    lastx = x;
	    myUT.glutPostRedisplay ();
	}
    }

    /* ARGSUSED3 */
    public void mouse (int button, int state, int x, int y) {
	if (button == GLUT.GLUT_LEFT_BUTTON) {
	    if (state == GLUT.GLUT_DOWN) {
		lastx = x;
		down = true;
	    } else {
		down = false;
	    }
	}
    }

    public void keyboard (char key, int x, int y) {
	switch (key) {
	    case 27:
		System.exit(0);
	    default:
		break;
	}
    }

    /* Main Loop */
    public void init () {
	myUT.glutInitWindowSize (500, 500);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutReshapeFunc ("myReshape");
	myUT.glutDisplayFunc ("display");
	myUT.glutCreateMenu ("menu");
	myUT.glutAddMenuEntry ("Show control points", 1);
	myUT.glutAddMenuEntry ("Hide control points", 0);
	myUT.glutAddMenuEntry ("Solid", 2);
	myUT.glutAddMenuEntry ("Wireframe", 3);
	myUT.glutAttachMenu (GLUT.GLUT_RIGHT_BUTTON);
	myUT.glutMouseFunc ("mouse");
	myUT.glutMotionFunc ("motion");
	myUT.glutKeyboardFunc ("keyboard");
	myUT.glutMainLoop ();
    }

    static public void main (String args[]) throws IOException {
	Frame mainFrame = new Frame ();
	mainFrame.setSize (508, 527);
	surface mainCanvas = new surface ();
	mainCanvas.init();
	mainFrame.add (mainCanvas);
	mainFrame.setVisible (true);
    }

}