/*
 *  bezcurve.java			
 *  This program uses evaluators to draw a Bezier curve.
 */

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

import jgl.GL;
import jgl.GLCanvas;

public class bezcurve extends GLCanvas {

    private static final float ctrlpoints [][] = {
    			{-4.0f, -4.0f, 0.0f},
			{-2.0f,  4.0f, 0.0f},
			{ 2.0f, -4.0f, 0.0f},
			{ 4.0f,  4.0f, 0.0f}};

    private void myinit () {
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 1.0f);
	myGL.glShadeModel (GL.GL_FLAT);
	myGL.glMap1f (GL.GL_MAP1_VERTEX_3, 0.0f, 1.0f, 3, 4, ctrlpoints);
	myGL.glEnable (GL.GL_MAP1_VERTEX_3);
    }

    public void display () {
    	int i;

	myGL.glClear (GL.GL_COLOR_BUFFER_BIT);
	myGL.glColor3f (1.0f, 1.0f, 1.0f);
	myGL.glBegin (GL.GL_LINE_STRIP);
	    for (i = 0; i <= 30; i++)
	    	myGL.glEvalCoord1f ((float)i/30.0f);
	myGL.glEnd ();
	/* The following code displays the control points as dots. */
	myGL.glPointSize (5.0f);
	myGL.glColor3f (1.0f, 1.0f, 0.0f);
	myGL.glBegin (GL.GL_POINTS);
	    for (i = 0; i < 4; i++)
	    	myGL.glVertex3fv (ctrlpoints[i]);
	myGL.glEnd ();
	myGL.glFlush ();
    }

    public void myReshape (int w, int h) {
        myGL.glViewport (0, 0, w, h);
        myGL.glMatrixMode (GL.GL_PROJECTION);
        myGL.glLoadIdentity ();
	if (w <= h) {
	    myGL.glOrtho (-5.0f, 5.0f,
	    		  -5.0f *(float)h/(float)w,
			   5.0f *(float)h/(float)w,
			  -5.0f, 5.0f);
	} else {
	    myGL.glOrtho (-5.0f *(float)w/(float)h,
	    		   5.0f *(float)w/(float)h,
			  -5.0f, 5.0f,
			  -5.0f, 5.0f);
	}
        myGL.glMatrixMode (GL.GL_MODELVIEW);
        myGL.glLoadIdentity ();
    }

    /* ARGSUSED1 */
    public void keyboard (char key, int x, int y) {
	switch (key) {
	    case 27:
		System.exit(0);
	    default:
		break;
	}
    }

    public void init () {
	myUT.glutInitWindowSize (500, 500);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutDisplayFunc ("display");
	myUT.glutReshapeFunc ("myReshape");
	myUT.glutKeyboardFunc ("keyboard");
	myUT.glutMainLoop ();
    }

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

}