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Hi Gib.<br>
<br>
I'm a newbie to VTK and haven't used the DepthPeeling class myself,
so I probably can't help you much... :/<br>
I guess if you used OpenGL rendering, get no errors and the class
tells you that "renderer->GetLastRenderingUsedDepthPeeling();" it
should work.<br>
Maybe you have to fiddle around with the settings a bit. Or the
implementation in your VTK version is broken...<br>
<br>
Best of luck,<br>
<br>
Kim<br>
<br>
<div class="moz-cite-prefix">Am 10.08.2014 04:37, schrieb Gib Bogle:<br>
</div>
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cite="mid:BD80F91C3E2E394894ED4780703D7F9E81D0D42E@uxcn10-tdc01.UoA.auckland.ac.nz"
type="cite">
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<div style="direction: ltr;font-family: Tahoma;color:
#000000;font-size: 10pt;">My card uses OpenGL 4.1 and supports
all the required extensions. Depth peeling does not work
though.<br>
<div style="font-family: Times New Roman; color: #000000;
font-size: 16px">
<hr tabindex="-1">
<div style="direction: ltr;" id="divRpF887898"><font
color="#000000" face="Tahoma" size="2"><b>From:</b> Kim
Rosenbohm [<a class="moz-txt-link-abbreviated" href="mailto:kim.rosenbohm@posteo.de">kim.rosenbohm@posteo.de</a>]<br>
<b>Sent:</b> Sunday, 10 August 2014 11:57 a.m.<br>
<b>To:</b> Gib Bogle; <a class="moz-txt-link-abbreviated" href="mailto:vtkusers@vtk.org">vtkusers@vtk.org</a><br>
<b>Subject:</b> Re: [vtkusers] Odd opacity issue<br>
</font><br>
</div>
<div>Hi Gib.<br>
<br>
Proper blending of transparent objects is only possible by
rendering them in the correct order.<br>
This can be tricky and if objects or polygons overlap you
even won't get away with sorting them...<br>
You probably want depth peeling for order-independent
transparency: <a moz-do-not-send="true"
href="http://www.vtk.org/Wiki/VTK/Depth_Peeling"
target="_blank">
http://www.vtk.org/Wiki/VTK/Depth_Peeling</a><br>
<br>
Best Regards,<br>
<br>
Kim<br>
<br>
<div class="moz-cite-prefix">Am 10.08.2014 01:48, schrieb
Gib Bogle:<br>
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<div style="direction:ltr; font-family:Tahoma;
color:#000000; font-size:10pt">The problem is simply
demonstrated with the opacity example:
<br>
<a moz-do-not-send="true"
href="http://www.vtk.org/Wiki/VTK/Examples/Cxx/Visualization/Opacity"
target="_blank">http://www.vtk.org/Wiki/VTK/Examples/Cxx/Visualization/Opacity</a><br>
<br>
Adding this line:<br>
sphereActor->SetPosition(1.0,0.0,0.0);<br>
and setting the opacity of both actors to 0.99 gives an
unexpected and unattractive result.<br>
<br>
I see that there have been posts about problems with
opacity/transparency as far back as 2006. Maybe there
is a solution...<br>
<div style="font-family:Times New Roman; color:#000000;
font-size:16px">
<hr tabindex="-1">
<div id="divRpF830592" style="direction:ltr"><font
color="#000000" face="Tahoma" size="2"><b>From:</b>
vtkusers [<a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:vtkusers-bounces@vtk.org"
target="_blank">vtkusers-bounces@vtk.org</a>] on
behalf of Gib Bogle [<a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:g.bogle@auckland.ac.nz"
target="_blank">g.bogle@auckland.ac.nz</a>]<br>
<b>Sent:</b> Sunday, 10 August 2014 11:25 a.m.<br>
<b>To:</b> <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:vtkusers@vtk.org" target="_blank">
vtkusers@vtk.org</a><br>
<b>Subject:</b> [vtkusers] Odd opacity issue<br>
</font><br>
</div>
<div>
<div style="direction:ltr; font-family:Tahoma;
color:#000000; font-size:10pt">Hi,<br>
I'm using vtkRenderWindowInteractor (VTK 5.10) in
Qt, rendering spheres. I'm trying to implement a
degree of transparency, like this:<br>
<br>
<span style="color:#800000">actor</span><span
style="color:#000000">-></span>GetProperty<span
style="color:#000000">()-></span><span
style="font-style:italic; color:#000000">SetOpacity</span><span
style="color:#000000">(</span><span
style="color:#800000">opacity</span><span
style="color:#000000"></span><span
style="color:#000000"></span><span
style="color:#000000"></span><span
style="color:#800000"></span><span
style="color:#000000">);</span><br>
<br>
applied to all the spheres.<br>
<br>
If opacity is less than 1 the image immediately
changes in unexpected ways. See the two attached
images, with opacity = 1.0 and 0.99. It looks as
if spheres have had their positions and sizes
changed. But when I rotate the scene it becomes
apparent that something else is happening. Some
of the "foreground" spheres move from left to
right (for example) while others apparently in the
foreground are moving right to left. It seems
that the order of rendering of the spheres, which
normally places the most remote first and the
nearest last, has somehow been messed up, so that
spheres at the back are being rendered last so
that they appear to be the closest. Maybe the
order has been simply reversed, but the visual
effect is made more confusing by parallax - my
brain is interpreting the bigger spheres as
closer.<br>
<br>
Is this a well-known issue, and is there a simple
way to fix it?<br>
<br>
Thanks<br>
Gib<br>
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