Atan2 table #1327
Atan2 table #1327
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It is a float based lookup table for atan2. Even for a small table size the lookup can be more than 50% faster than atan2(). While still being relatively accurate.
The space control game functions the game after this change. There wouldn't be a noticeable speed up after this change. This atan2 is used when locking onto the stars. If the nPoints parameter for the atan2 is lowered below 128 then there is a noticeable bias when locking onto the stars. I have selected a large enough value so that this is not the case. I made the atan2 table be static so that all fvectors could share the same one.
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Does this improve anything? How much faster is "faster"? LUT's are great on limited hardware that is needing the calculation very often - this isn't the case here. For now I only see increased code complexity that doesn't add anything. But maybe I'm just not seeing the intention here, that's why I'm asking. |
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One problem with this is that in cases where LUTs are actually useful they can easily contain little idiosyncrasies on a per-engine basis (round-off errors, edge cases and the like). So you end up having to have one for each engine anyway. |
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@foobar13372 it is 65% faster than the float atan2 call. While titanic may not speed up that much since the atan2 is not used much something like bladerunner does a lot more atan2 so it would benefit more. @lskovlun I'm not sure I understand, how can an engine do an atan2 function correctly, but not be replaced by a more general atan2 call? I'm thinking of star trek here. We can always select a lower number of points/bits to model less precision to stay true to an engine. |
Making a atan2 table based only on ints may also be useful to add.