Flightgear-2.8.0 with quad buffered stereo

In the article Flightgear with quad buffered stereo I have written about how to get quad buffered stereo to work with the famous flight simulator FlightGear. Recently FlightGear-2.8.0 has been released. The problem with quad buffered stereo still persists with FlightGear-2.8.0 .

One expects to enable stereoscopic mode in FlightGear starting it with the following line:

export OSG_STEREO_MODE=QUAD_BUFFER;export OSG_STEREO=ON; fgfs

When starting flightgear this way, one gets the following console output and no stereoscopic view:

Warning: detected OpenGL error ‘invalid operation’ after RenderBin::draw(,)

Getting FlightGear to work with quad-buffered stereo

The reason for the above error message and the resulting broken stereo mode is, that the stereo context does not get initialized properly. The details are described here: Flightgear with quad buffered stereo. Unfortunately the patch I proposed in the mentioned post does not work for flightgear-2.8.0. However, the good news is, it only required a slight modification, the WindowBuilder.cxx file no longer is in src/Main, but in the src/Viewer directory. You can download the new patch from here: flightgear-2.8.0-stereoscopic.patch (1771)

Hopefully the patch finds its way into the next flightgear release.

As usual for quad buffered stereo, you have to use a professional graphics board that supports quad buffered stereo, like a NVIDIA Quadro FX or a Ati FireGL and proper display hardware, like shutter glasses, a HMD or a stereoscopic projection system, to benefit from it. To use the quad buffered stereo mode start flightgear with the environment variables mentioned above. Afterwards you probably have to enable quad buffered stereo mode by selecting the Stereoscopic View Options Item in the the View menu.

The Gentoo way

For gentoo users I have created an overlay. Like the previous one it contains patches and modified ebuilds for flightgear with working quad buffer support. You may get the overlay from here: flightgear-2.8.0 overlay (1800) Download the overlay and extract it in /usr/local/portage. Be sure to include the following line in your /etc/make.conf:

PORTDIR_OVERLAY=”/usr/local/portage”

Then emerge flightgear and enjoy it in three dimensions.

Have fun

Jürgen

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Flightgear-2.4.0 with quad buffered stereo

In the post Flightgear with quad buffered stereo I have written about how to get quad buffered stereo to work with the famous flight simulator FlightGear.  Recently FlightGear-2.4.0 has been released. The problem with quad buffered stereo still persists with FlightGear-2.4.0 .

One expects to enable stereoscopic mode in FlightGear starting it with the following line:

export OSG_STEREO_MODE=QUAD_BUFFER;export OSG_STEREO=ON; fgfs

When starting flightgear this way, one gets the following console output and no stereoscopic view:

Warning: detected OpenGL error ‘invalid operation’ after RenderBin::draw(,)

Getting FlightGear to work with quad-buffered stereo

The reason for the above error message and the resulting broken stereo mode is, that the stereo context does not get initialized properly.  The details are described here: Flightgear with quad buffered stereo. However, the  good news is, that the patch I proposed in the mentioned post, still works with FlightGear-2.4.0. You can download the patch from here: flightgear-2.0.0-stereoscopic.patch (1325)

As usual for quad buffered stereo, you have to use a professional graphics board that supports quad buffered stereo, like a NVIDIA Quadro FX or a Ati FireGL and proper display hardware, like shutter glasses, a HMD or a stereoscopic projection system, to benefit from it. To use the quad buffered stereo mode start flightgear with the environment variables mentioned above. Afterwards you probably have to enable quad buffered stereo mode by selecting the Stereoscopic View Options Item in the the View menu.

With the previous version, when using the quad buffered stereo mode in flightgear, there occurred some graphics errors. Some cockpit controls and other scene details contained yellow lines, like a wireframe, which were not there when starting FlightGear in “normal” display mode. These problems seem to be gone with Flightgear-2.4.0. At least I did not notice them  anymore.

The Gentoo way

For gentoo users I have created an overlay. Like the previous one it contains patches and modified ebuilds for flightgear with working quad buffer support.  You may get the overlay from here: flightgear-2.4.0 overlay (880) Download the overlay and extract it in /usr/local/portage. Be sure to include the following line in your /etc/make.conf:

PORTDIR_OVERLAY=”/usr/local/portage”

Then emerge flightgear and enjoy it in three dimensions.

Have fun

Jürgen

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FlightGear with quad buffered stereo

With my upcoming new headtracking driver for the vusix vr920 hmd it is likely that I manage to get the famous flight simulator FlightGear to work with it. This led me again to the problem that FlightGear does not work in quad buffered stereo, as  I described in my comment to FlightGEAR 2.0.0 on GENTOO.

One expects to enable stereoscopic mode in FlightGear starting it with the following line:

export OSG_STEREO_MODE=QUAD_BUFFER;export OSG_STEREO=ON; fgfs

When starting flightgear this way, one gets the following console output and no stereoscopic view:

Warning: detected OpenGL error ‘invalid operation’ after RenderBin::draw(,)

Getting FlightGear to work with quad-buffered stereo

Doing some code analysis in OpenSceneGraph-2.8.0 I discovered the following lines of code in View.cpp:

osg::DisplaySettings* ds = osg::DisplaySettings::instance();
if (ds->getStereo())
{
switch(ds->getStereoMode())
{
case(osg::DisplaySettings::QUAD_BUFFER): traits->quadBufferStereo = true; break;
case(osg::DisplaySettings::VERTICAL_INTERLACE):
case(osg::DisplaySettings::CHECKERBOARD):
case(osg::DisplaySettings::HORIZONTAL_INTERLACE): traits->stencil = 8; break;
default: break;
}
}

It seems that the stereo context in FlightGear does not get initialized properly in WindowBuilder::makeDefaultTraits(bool stencil). Thus these lines have to be added to WindowBuilder.cxx. For convenience here is the patch against  FlightGear-2.0.0: flightgear-2.0.0-stereoscopic.patch (1325)

Perhaps some nice FlightGear developer can include this into upstream code. You have to use a professional graphics board that supports quad buffered stereo, like a NVIDIA Quadro FX or a Ati FireGL and proper display hardware, like shutter glasses, a HMD or a stereoscopic projection system, to benefit from it.

Problems remaining

When using the quad buffered stereo mode in flightgear there occur some graphics errors. These are not very annoying, but they are there. Some cockpit controls and other scene details contain yellow lines, like a wireframe,  which are not there when starting FlightGear in “normal” display mode. I suspect this to be another bug in FlightGear, which has still to be located. See the screenshots below for details. The problematic parts of the scenes are marked red. Especially the night pictures show the problem. This problem does not only exist in quad buffered stereo mode, but also in other stereo modes like HORIZONTAL_SPLIT.

flightgear_1

FlightGear by day, quad-buffered stereo, with errors

flightgear_2

FlightGgear by day, no stereo, without errors

flightgear_3

FlightGear by night, quad-buffered stereo, with errors

flightgear_4

FlightGear by night, no stereo, without errors

The Gentoo way

For gentoo users here is my overlay including the modified ebuild: flightgear-2.0.0-stereoscopic_overlay.tar.gz (1182) Download the modified overlay (including the patches) and extract it in /usr/local/portage. Be sure to include the following line in your /etc/make.conf:

PORTDIR_OVERLAY=”/usr/local/portage”

Then emerge flightgear and enjoy it in three dimensions.

Have fun

Jürgen

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