{ RCSid: $Id: tmesh.cal,v 2.2 2004/03/11 23:16:01 greg Exp $ }
{
	Interpolate triangle-mesh values using barycentric coordinates.

	A1		= Major axis (0==X, 1==Y, 2==Z)
	A2 through A10	= Surface normal perturbation matrix
or:
	A2 through A7	= Lookup in 2-dimensional pattern or texture
}
					{ Get dominant coordinates }
bu = select(arg(1)+1, Py, Pz, Px);
bv = select(arg(1)+1, Pz, Px, Py);
					{ Compute variables }
v1 = bu*arg( 2) + bv*arg( 3) + arg( 4);
v2 = bu*arg( 5) + bv*arg( 6) + arg( 7);
v3 = bu*arg( 8) + bv*arg( 9) + arg(10);
					{ Surface normal perturbation }
nf = 1/sqrt(v1*v1 + v2*v2 + v3*v3);
dx = v1*nf - Nx;
dy = v2*nf - Ny;
dz = v3*nf - Nz;
					{ Tiled texture coordinates }
u = frac(v1);
v = frac(v2);