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<DIV><FONT face=Arial size=2>Hi John</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks very much for the advice.
Unfortunately I can't rely on decent texture mapping. Many of the users
have machines that can only be described as a form of
punishment. I've had to keep the visualization pretty basic, but all
that is required anyway is to choose parts of a broken up surface to be
fitted to planes so they can run a simplified model.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I tried your idea anyway, even just using an image
actor (no textures) comes out all wrong on their machines - though
it looks right on mine. I know many of the users have old ATI chips, which
I've had problems with before. Ironically on the machines that
could handle your trick, the straightforward rendering is pretty quick
anyway.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In the worst case I could continue to do all the
transformations with VTK and then paint on my own canvas, do a bitblt and
draw the latest polygon segment with XOR.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Any other suggestions?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Thanks</FONT></DIV>
<DIV><FONT face=Arial size=2>Malcolm</FONT> </DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=john.biddiscombe@mirada-solutions.com
href="mailto:john.biddiscombe@mirada-solutions.com">John Biddiscombe</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=malcolm@geovision.co.za
href="mailto:malcolm@geovision.co.za">Malcolm Drummond</A> ; <A
title=vtkusers@vtk.org href="mailto:vtkusers@vtk.org">vtkusers</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, September 24, 2003 11:26
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: [vtkusers] drawing very
quickly in an overlay (tracking mouse with a line)</DIV>
<DIV><BR></DIV>
<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>
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<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></BLOCKQUOTE></BODY></HTML>