Re: [Gerbv-devel] Windows version of 2.1.x?
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From: Peter C. <pc...@ca...> - 2008-10-16 00:22:50
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On Wed, 2008-10-15 at 15:21 -0400, Julian wrote: > I guess this is another reason we should probably try to push out a > new Windows version as soon as possible. I'll look at the rendering > speedup code today and try to get that knocked out. Depending on how much panning about you do, coarse clipping with an r-tree (e.g. how PCB does it), might save you time. The cost of building the r-tree if O(>n), but searching it is pretty quick. Throw it a bounding box, it fires back objects within that. http://en.wikipedia.org/wiki/R-tree PCB's implementation seems quite good, although you have to be careful not to delete items from the r-tree from _within_ an r_tree search callback (doesn't seem to crash - just messes up the rest of the search). One point where PCB probably falls down, is that it builds its r-trees for various objects sequentially (edges in a polygon contour, for example), which can result in poorly conditioned searches. The wikipedia page has some links to better algorithms for loading the initial data. Best wishes, -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) |