strmxor shows no difference, klayout xor shows 85, dbu 99.999 vs 1000

[stefanottili]

strmxor a.oas b.oas xor.oas shows not differences
klayout a.oas -s b.oas, xor using 8 threads, 500 tile, healing shows 85 differences.

a.oas 99.999 dbu vs b.oas 1000 dbu, only 10 polygons.

test_klayout_scaled_xor.tgz

[klayoutmatthias]

Okay, there is a difference between strmxor and KLayout XOR when it comes to different DBUs:

• strmxor will use the minimum of both and scale the other layout accordingly.
• KLayout XOR will use the LCM of both layouts. This is meant for DBU pairs where one is a multiple of the other. GCD would be safer, but there is a risk this value is very small and hence the coordinate space overflows.

In the test case, the LCM of 0.0100000016391 and 0.001 is, ahem, 83265.1532405.

Maybe it is better to take the minimum for the KLayout XOR too.

[stefanottili]

Ah, ok. There are only a handful of DBU’s that make sense, I’l try to avoid writing not rounded ones.