import javax.media.j3d.*;
import javax.vecmath.*;

// Origin at center of solid. Sides of length 2.

public class NormalTetra extends Shape3D {
	private static final float ycenter = (float)Math.sqrt(1.0/6.0);
	private static final float zcenter = (float)Math.sqrt(1.0/3.0);
	private static final float sqrt3 = (float)Math.sqrt(3.0);
	private static final float sqrt24_3 = (float)Math.sqrt ( 8.0/3.0);

	private static final Point3f p1 = new Point3f ( -1.0f, -ycenter, zcenter );
	private static final Point3f p2 = new Point3f ( 1.0f, -ycenter, zcenter );
	private static final Point3f p3
		= new Point3f ( 0.0f, -ycenter, -sqrt3 + zcenter );
	private static final Point3f p4
		= new Point3f ( 0.0f, sqrt24_3 -ycenter, 0.0f );

	private static final Point3f[] verts = {
		p1, p2, p4, // front face
		p1, p4, p3, // left back face
		p2, p3, p4, // right back face
		p1, p3, p2, // bottom face
	};

	/* assumes it is a triangle */
	private Vector3f normalizeTriangle ( Point3f p1, Point3f p2, Point3f p3 ) {
		//Point3f p1 = triangle[0];
		//Point3f p2 = triangle[1];
		//Point3f p3 = triangle[2];
		Vector3f v1 = new Vector3f ( p2.x - p1.x, p2.y - p1.y, p2.z - p1.z );
		Vector3f v2 = new Vector3f ( p3.x - p1.x, p3.y - p1.y, p3.z - p1.z );
		Vector3f v3 = new Vector3f ( v1.y * v2.z - v1.z * v2.y,
			v1.z * v2.x - v1.x * v2.z, v1.x * v2.y - v1.y * v2.x );
		float norm = (float) Math.sqrt ( v3.x*v3.x + v3.y*v3.y + v3.z*v3.z ); 
		v3.x /= norm;
		v3.y /= norm;
		v3.z /= norm;
		return v3;
	}

	/* from Lit.java */
	private void createMaterials ( Appearance[] mats ) {
		Color3f black = new Color3f ( 0.0f, 0.0f, 0.0f );
		Color3f deepRed = new Color3f ( 0.9f, 0.2f, 0.1f );
		Color3f royalBlue = new Color3f ( 0.1f, 0.3f, 0.9f );
		Color3f white = new Color3f ( 1.0f, 1.0f, 1.0f );

		for ( int i = 0; i < 4; i++ )
			mats[i] = new Appearance();

		mats[0].setMaterial (
			new Material ( deepRed, black, deepRed, black, 1.0f ) );
		mats[1].setMaterial (
			new Material ( royalBlue, black, royalBlue, black, 1.0f ) );
		mats[2].setMaterial (
			new Material ( deepRed, black, deepRed, white, 1.0f ) );
		mats[3].setMaterial (
			//new Material ( royalBlue, black, royalBlue, white, 1.0f ) );
			new Material ( royalBlue, black, royalBlue, white, 3.0f ) );
	}

	/* From ColorTetra  --
	private static final Color3f c1 = new Color3f ( 1.0f, 0.0f, 0.0f );
	private static final Color3f c2 = new Color3f ( 0.0f, 1.0f, 0.0f );
	private static final Color3f c3 = new Color3f ( 1.0f, 1.0f, 1.0f );
	private static final Color3f c4 = new Color3f ( 0.0f, 0.0f, 1.0f );

	private static final Color3f[] colors = {
		c1, c2, c4,
		c1, c4, c3,
		c2, c3, c4,
		c1, c3, c2,
	};
	*/

	public NormalTetra() {
		TriangleArray tetra = new TriangleArray ( 12, 
			TriangleArray.COORDINATES | TriangleArray.NORMALS );
		tetra.setCoordinates (0, verts );
		//tetra.setColors (0, colors );
		Vector3f[] norms = new Vector3f[12];

		norms[0] = norms[1] = norms[2] = normalizeTriangle ( p1, p2, p4 );
		norms[3] = norms[4] = norms[5] = normalizeTriangle ( p1, p4, p3 );
		norms[6] = norms[7] = norms[8] = normalizeTriangle ( p2, p3, p4 );
		norms[9] = norms[10] = norms[11] = normalizeTriangle ( p1, p3, p2 );
		tetra.setNormals ( 0, norms );

		Appearance[] mats = new Appearance[4];
		createMaterials ( mats );
	
		//tetra.setMaterials ( 0, mats );
		this.setGeometry ( tetra );
		this.setAppearance ( mats[3] );
	}
}