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by gchadwick
1521 days ago
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Of course when you're doing such intersection calculations you know the things you're intersecting are very close. You don't need a general method that can test arbitrarily sized and spaced polygons against each other. You need a method to determine what is sufficiently close to each other to be worthy of a more detailed check. Then a more specific method to do this check. You could use 32 bit integers with all shapes specified vs say a 0.1 nm grid giving you around a maximum 0.4m x 0.4m chip size which seems ample. Then when you want to check for rules violations in the cases like you specify with very fine precision use a dedicated check that can assume the relevant geometry is within a small number of grid points of each other. For example the check could work using relative coordinates rather than absolute so say switch to a grid on a 0.00001nm basis (to pull an arbitrary precision out of a hat) and convert the 32-bit absolute 0.1nm coords to relative 32-bit 0.00001nm coords. Easier said then done to be sure (as you say the tools are egregiously expensive!) but just saying I need a 64-bit or a 128-bit float isn't trying to get to the grips with the problem, just hoping you wave it away with more bits. |
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Your line sweep data structure effectively already does that. I recommend reading the Hobby paper and thinking about how it works. And then you should think about how you differentiate inside from outside when you union/difference your polygons.
Any segments in the line sweep data structure simultaneously have already demonstrated that they need the detailed check.
If you want to argue this, you're going to need to study up on about 40 years of prior art. Given how much money this is worth and how many really smart people went after it (it basically drove the field of Computational Geometry for decades), the probability of you contributing something new to the current algorithms is basically zero.
However, the probability of you contributing something new to parallel DRC algorithms is really quite decent. Nobody I know of has yet come up with "good" parallel algorithms for DRC--most of them are hacks that quite often break down when they hit even common cases.
Being able to handle DRC on a billion VLSI polygons/10 billion line segments in a parallel fashion would be quite an advance, and the field is waiting for it.