[osg-users] Changing minFilter/magFilter of texture in osgVolume::RayTracedTechnique

Sailesh Sidhwani ssidhwan at mathworks.com
Tue Apr 16 12:10:28 PDT 2019

I have RayTracedTechnique putting graphics on the screen, but things aren't rendering correctly. The culprit is the 'osg::Texture3D::LINEAR' choice that is used by default as the min/mag filter for the Texture3D object created by RayTracedTechnique. I'd like to change to NEAREST as I'm working with segmented/ labeled volume.   The problem I'm seeing is that when I use the setMinFilter and setMaxFilter methods on the associated ImageLayer, things aren't getting updated for some reason. I know that's what's going on because if I actually edit the code in RayTracedTechnique.cpp to use NEAREST for the min/max filter on the Texture3D, I get the texture I want on the screen.

Here is some code for context:

            osg::ref_ptr<osgVolume::Volume> volume = new osgVolume::Volume;

            osg::ref_ptr<osgVolume::VolumeTile> tile = new osgVolume::VolumeTile;

            osg::ref_ptr<osg::Image> image_3d = createTexture3D(data,xfer_table);

            osg::ref_ptr<osgVolume::ImageLayer> layer = new osgVolume::ImageLayer(image_3d.get());


            layer->addProperty(new osgVolume::AlphaFuncProperty(0.02f));

            osg::ref_ptr<osgVolume:: RayTracedTechnique > technique = new osgVolume:: RayTracedTechnique ();

            layer->setMagFilter(osg::Texture3D:: NEAREST);
            layer->setMinFilter(osg::Texture3D:: NEAREST);

Here is how the output looks when I edit RayTracedTechnique.cpp to use NEAREST minFilter/magFilter. This is how I expect it to look

[cid:image001.png at 01D4F464.82427F50]

Default RayTracedTechnique.cpp (which uses LINEAR minFilter/magFilter): (Not expected)
[cid:image003.png at 01D4F466.84604450]

How can I force the Texture3D object created by RayTracedTechnique to use NEAREST for minFilter/magFiltering?

I'm using OSG 3.0. I know I need to upgrade, but I didn't see any way to do this even in OSG 3.6

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