/usr/share/radiance/weave.cal is in radiance-materials 4R1+20120125-1.
This file is owned by root:root, with mode 0o644.
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| 1 2 3 4 5 6 7 8 9 10 11 12 | {
	weave.cal - function for simple diagonal weave pattern
			on horizontal surface.
	
	A1 is weave square size.
}
weave = f_weave(frac((Px+Pz)/1.4142/A1),frac((Px-Pz)/1.4142/A1));
f_weave(m1,m2) = if (m1-.5, if (m1-.55, f_weave(m2,1.05-m1), .1),
		 if (m2-.5, if (m2-.55, f_weave(1.05-m2,m1), .1),
	if (m1-.05, if (m2-.25, if (m2-.3, .5, .1), if (m2-.05, 1, .1)), .1)));
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