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<DIV><FONT face=Arial size=2>Hi</FONT></DIV>
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<DIV><FONT face=Arial size=2>Can anyone offer advice on drawing very quickly in
an overlay?</FONT></DIV>
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<DIV><FONT face=Arial size=2>I have a companion '2D' window which
basically renders a 3D parallel projection that has been transformed by the
camera matrix from the main '3D' window. In the second window the user creates
fence polygons around regions of interest with a mouse - after which I do
point-in-polygon stuff etc. So far so good - however on large datasets the
rendering of the polygon segment lags way behind the mouse
position.</FONT></DIV>
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<DIV><FONT face=Arial size=2>I draw the most recent segment of the fence
polygon (ie. the one that is tracking the mouse) in an
overlay layer in the hope that I could use backing store on the background
renderer, but I'm not seeing any real difference in performance. Maybe I'm not
using backing store correctly - I switch backing store on when I start catching
mouse events for the polygons, switch off when I have the whole polygon, but all
the rendering in-between seems to be refreshing both renderers.</FONT></DIV>
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<DIV><FONT face=Arial size=2>Has anyone experience with
this?</FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks</FONT></DIV>
<DIV><FONT face=Arial size=2>Malcolm Drummond<BR>GeoVision
cc</FONT></DIV></BODY></HTML>