[Paraview] [EXTERNAL] Alpha compositing reverses the depth of objects

[Scott, W Alan]

This is a graphics card issue, as you suspected.


*         I was not able to run your test below.  It keeps saying 'No tests were found'.

*         The platform that I created this bug with NX/ Linux.  NX uses a Mesa, software rendered buffer.  As far as I know, said Mesa could be as old as the pioneers.  I was able to recreate this issue.

*         I logged into a blade that allowed me to use a real graphics card (NVidia), and the issue was not there.

*         I changed the rendering threshold remote server, then remote server'd into redsky.  Issue also was not there.

I believe that this proves this is not a ParaView bug, but rather an issue with old versions of Mesa.  Further, I believe you are correct - it is a depth peeling issue in the graphics cards

I am closing the bug.  If I messed up, we can always reopen.

Thanks,


Alan

From: Utkarsh Ayachit [mailto:utkarsh.ayachit at kitware.com]
Sent: Monday, October 21, 2013 11:23 AM
To: Scott, W Alan
Cc: Burlen Loring; Christopher L. P. Wolfe; paraview at paraview.org
Subject: Re: [Paraview] [EXTERNAL] Alpha compositing reverses the depth of objects

Alan,

I can reproduce the problem when I explicitly turn off depth peeling (Edit |Settings : Render View | General : Enable Depth Peeling).
Can you run the following test and post the output? We'll know whether Depth peeling is supposed to work with your graphics driver.

ctest -R TestSystemCaps -V

Utkarsh


On Mon, Oct 21, 2013 at 12:47 PM, Scott, W Alan <wascott at sandia.gov<mailto:wascott at sandia.gov>> wrote:
I replicated it on Linux.  Written up as bug number 14325.  Very easy to replicate.

Thanks,

Alan

From: Utkarsh Ayachit [mailto:utkarsh.ayachit at kitware.com<mailto:utkarsh.ayachit at kitware.com>]
Sent: Monday, October 21, 2013 4:18 AM
To: Scott, W Alan; Burlen Loring
Cc: Christopher L. P. Wolfe; paraview at paraview.org<mailto:paraview at paraview.org>
Subject: Re: [Paraview] [EXTERNAL] Alpha compositing reverses the depth of objects

Alan,

Did you reproduce this on a Mac or some other platform as well? Depth peeling doesn't work on certain Macs. Without Depth peeling, translucency will indeed manifest the issues seen. Burlen recently pushed/is pushing some changes to extend support for more Macs. CC-ing Burlen in case he wants to elaborate on what's supported and not.

Utkarsh

On Mon, Oct 14, 2013 at 1:05 PM, Scott, W Alan <wascott at sandia.gov<mailto:wascott at sandia.gov>> wrote:
GGrrr - that looks like a bug to me.  I replicated this bug with Wavelet/ Contour, remote server, on current master.  Want me to write up a bug, or do you want to do it?

Thanks for reporting this bug.

Alan

From: paraview-bounces at paraview.org<mailto:paraview-bounces at paraview.org> [mailto:paraview-bounces at paraview.org<mailto:paraview-bounces at paraview.org>] On Behalf Of Christopher L. P. Wolfe
Sent: Monday, October 14, 2013 10:15 AM
To: paraview at paraview.org<mailto:paraview at paraview.org>
Subject: [EXTERNAL] [Paraview] Alpha compositing reverses the depth of objects

Hi all,

I'm having a weird problem with paraview (I'm using 4.01 for the Mac). Basically, if have an object with multiple layers, turning on transparency reverses the depth of the layers. This is easier to show than describe:

Here I have a scene constructed using the contour filter with alpha = 1.00:
[cid:image001.png at 01CECE6A.052180A0]

This is the same scene with alpha = 0.99:
[cid:image002.png at 01CECE6A.052180A0]

Several of the layers which where hidden in the back are now in front. In addition, several layers have completely transparent "windows" in them, even though the layers should just barely be transparent.

Any suggestions on how to fix/workaround this issue?

Thanks,
Christopher


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