This module has a helper function that converts an array of quad indices to
an array of triangle indices. So, given the array
[ [0,1,2,3], [4,5,1,0] ], which
specifies the indices of two quads, this module will give an array
[ [0,1,2], [0,2,3], [4,5,1], [4,1,0] ]. And if you render these indices as triangles,
you will draw the two quads, but as four triangles instead of as two quads.
cells, an array of quad indices, return the corresponding array of triangle
indices. Note that it is assumed that the indices in
cells are stored in
cells = [ [0,1,2,3], [4,5,1,0] ], then the functions returns
[ [0,1,2], [0,2,3], [4,5,1], [4,1,0] ].