Author: Robert Hyatt
Date: 12:37:05 12/06/99
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On December 06, 1999 at 11:29:56, Bas Hamstra wrote: >Hi Bob and other bb experts, > >What do you use the rotated bb's for, exactly: only for movegeneration, or also >for attack detection? > >I ask this because I saw in Crafty some code to detect blocking of sliding >attacks, like I do it. Whith a BlockMask[File][Rank]. I thought the essence of >the rotated bb's is that you can avoid this block checking, so why this >block-code in Crafty? > it is sometimes a quick way to answer questions like "is there a queen" diagonally behind this bishop so that they are both bearing on the target? The rotated lookup is fast, but if you already have two squares in mind and want to know if the path between them is open or blocked, it is faster to simply AND the occupied squares bitmap with a mask that has a 1 bit set on every square between the two squares in question... > > >Regards, >Bas Hamstra.
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