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<DIV><SPAN class=756122409-24092003><FONT face=Arial color=#0000ff size=2>You'll
have to actually capture the back buffer and redisplay it, turning on and off
backing store won't circumvent the pipeline re-execution which is your
trouble.</FONT></SPAN></DIV>
<DIV><SPAN class=756122409-24092003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=756122409-24092003><FONT face=Arial color=#0000ff size=2>Nifty
tip : Try capturing the original window using renderwindow->image, then
generate a texture from it. then display the texture as the full image in your
polygon window and overlay your polylines on that. Quick updates, no
trouble.</FONT></SPAN></DIV>
<DIV><SPAN class=756122409-24092003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=756122409-24092003><FONT face=Arial color=#0000ff
size=2>JB</FONT></SPAN></DIV>
<DIV><SPAN class=756122409-24092003></SPAN> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Malcolm Drummond
[mailto:malcolm@geovision.co.za]<BR><B>Sent:</B> 24 September 2003
08:31<BR><B>To:</B> vtkusers<BR><B>Subject:</B> [vtkusers] drawing very
quickly in an overlay (tracking mouse with a line)<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Hi</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Can anyone offer advice on drawing very quickly
in an overlay?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<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>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<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>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<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></BLOCKQUOTE></BODY></HTML>