question: public CCVertex3D vertex ( ccGridSize pos ) { int index = ( pos . x * ( gridSize_ . y + 1 ) + pos . y ) * 3 ; CCVertex3D vert = new CCVertex3D ( vertices . get ( index + 0 ) , vertices . get ( index + 1 ) , vertices . get ( index + 2 ) ) ; return vert ; }
target:  returns the vertex at a given position 