float E = 0.001;
size(100,100,OPENGL);

_checkEqual( screenX( 0, 0, 0 ) , 0, E);
_checkEqual( screenX( 10, 0, 0 ), 10, E);
_checkEqual( screenX( 0, -10, 0 ), 0, E);
_checkEqual( screenX( 0, 0, 90 ), 1324.5187, E);
_checkEqual( screenX( 5, 5, 5 ), 2.2427292, E);
_checkEqual( screenX( -5, -5, -5 ), -1.997906, E);

_checkEqual( screenY( 0, 0, 0 ), 0, E);
_checkEqual( screenY( 10, 0, 0 ), 0, E);
_checkEqual( screenY( 0, -10, 0 ), -10, E);
_checkEqual( screenY( 0, 0, 90 ), 1324.5190528383391, E);
_checkEqual( screenY( 5, 5, 5 ), 2.2427292, E);
_checkEqual( screenY( -5, -5, -5 ), -1.997906, E);

_checkEqual( screenZ( 0, 0, 0 ), 0.9090909, E);
_checkEqual( screenZ( 10, 0, 0 ), 0.9090909, E);
_checkEqual( screenZ( 0, -10, 0 ), 0.9090909, E);
_checkEqual( screenZ( 0, 0, 90 ), 3.584886, E);
_checkEqual( screenZ( 5, 5, 5 ), 0.90290177, E);
_checkEqual( screenZ( -5, -5, -5 ), 0.9146044, E);