// file: j3dvisual/examples/tilogo/Torus.java

// written by Jan Köhnlein

import javax.media.j3d.*;
import javax.vecmath.*;
import com.sun.j3d.utils.geometry.*;

public class Torus extends Shape3D {
    /** the radius of the center circle */
    private double radius = 1.;

    /** the radius of the tube */
    private double thickness = 0.2;

    /** number of longitudes */
    private int iCount = 20;

    /** number of latitudes */
    private int jCount = 10;
    

    public Torus() {
	computeGeometry();
    }	

    public Torus( double radius, double tickness ) {
	this.radius = radius;
	this.thickness = thickness;
	computeGeometry();
    }

    public Torus( int iCount, int jCount, double radius, double tickness ) {
	this.iCount = iCount;
	this.jCount = jCount;
	this.radius = radius;
	this.thickness = thickness;
	computeGeometry();
    }

    public Torus( int iCount, int jCount ) {
	this.iCount = iCount;
	this.jCount = jCount;
	computeGeometry();
    }

    public void computeGeometry() {
	Transform3D turnMatrix = new Transform3D();
	double angle = 0;
	double innerAngle = 0;
	Point3f center = null;
	
	
	Point3f[] vertices = new Point3f[ ( iCount + 1 )  * jCount ];
	int[] indices = new int[ 4 * ( iCount + 1 ) * jCount ];
	Point2f[] textureCoords = new Point2f[ ( iCount + 1 ) * jCount ];
	Vector3f[] normals = new Vector3f[ ( iCount + 1 ) * jCount ];
	
	int index = 0;

	for ( int i = 0; i <= iCount; ++i ) {
	    angle = 2. * i * Math.PI / iCount;
	    center = new Point3f
		( ( float ) ( Math.cos( angle ) * radius ),
		  ( float ) ( Math.sin( angle ) * radius ), 
		  0 );
	    turnMatrix.rotZ( angle + Math.PI / 2. );
	    turnMatrix.setTranslation( new Vector3f( center ) );

	    for ( int j = 0; j < jCount; ++j ) {
		innerAngle = 2. * j * Math.PI / jCount;

		// vertex 
		vertices[ index ] = 
		    new Point3f
			( 0, 
			  ( float ) ( Math.cos( innerAngle ) * thickness ), 
			  ( float ) ( Math.sin( innerAngle ) * thickness ) );
		turnMatrix.transform( vertices[ index ] );

		// normals 
		normals[ index ] = new Vector3f ();
		normals[ index ].sub( vertices[ index ], center );
		normals[ index ].normalize();

		// texture coordinates
		textureCoords[ index ] = new Point2f
		    ( ( ( float ) i ) / iCount , ( ( float ) j ) / jCount );

		// face
		indices[ 4 * index ] = j + i * jCount;
		indices[ 4 * index + 1 ] = ( j + 1 ) % jCount + i * jCount;
		indices[ 4 * index + 2 ] = ( j + 1 ) % jCount + 
		    ( i + 1 ) * jCount;
		indices[ 4 * index + 3 ] = j + ( i + 1 ) * jCount;
		
		index ++;
	    }
	}

	// initialize QuadArray
	QuadArray quad = new QuadArray
	    ( 4 * iCount * jCount, GeometryArray.COORDINATES 
	      | GeometryArray.NORMALS 
	      | GeometryArray.TEXTURE_COORDINATE_2 
	      | GeometryArray.COLOR_3 );
	Color3f colour = new Color3f( 0f, 0f, 1f );
	for ( int i = 0; i < iCount * jCount; ++i ) {
	    for ( int j = 0; j < 4; ++j ) {
		quad.setCoordinate
		    ( 4 * i + j, vertices[ indices[ 4 * i + j ] ] );
		quad.setTextureCoordinate
		    ( 4 * i + j, textureCoords[ indices[ 4 * i + j ] ] );
		quad.setNormal
		    ( 4 * i + j, normals[ indices [ 4 * i + j ] ] );
		quad.setColor
		    ( 4 * i + j, colour );
	    }
	}
	

	setGeometry( quad );
    }
}