package sample.web3d;
import static util.Generic3DUtil.*;

public class Tetrahedron {
	/*
	 * 正多面体の隣り合う面同士のなす角 (http://en.wikipedia.org/wiki/Table_of_polyhedron_dihedral_angles)
	 * 正四面体   acos(1/3)
	 * 正六面体   π/2
	 * 正八面体   π - acos(1/3)
	 * 正十二面体 π - atan(2)
	 * 正二十面体 π - acos(sqrt(5)/3)
	 */
	public static void main(String[] args) {
		double len = 200;
		double dihedral = Math.acos(-1.0/3)/PI*180;
			
		start();
		stroke(0xff0000);
//		ribbonWidth(5);
		
		bank(dihedral/2);
		turn(-120);
		bank(-dihedral/2);
		forward(len);
		
		bank(-dihedral/2);
		turn(120);
		bank(dihedral/2);
		forward(len);
		
		bank(-dihedral/2);
		turn(120);
		bank(dihedral/2);
		forward(len);
		
		bank(dihedral/2);
		turn(-120);
		bank(-dihedral/2);
		forward(len);
		
		bank(dihedral/2);
		turn(-120);
		bank(-dihedral/2);
		forward(len);
		
		bank(-dihedral/2);
		turn(120);
		bank(dihedral/2);
		forward(len);
		
		bank(-dihedral/2);
		turn(120);	
		bank(dihedral/2);
		forward(len);	

		finish();
	}
}