[osg-users] [Depth Buffer rendering]

[Wojciech Lewandowski]

Hi Mathieu,

Sorry I don't have the time to compile and test your code, but I saw the 
screenshot and it looks like your depth texture gets rendered and applied to 
the object. What you may need to do is to make sure you set up RTT camera 
transform exactly as main camera transforms, and texture coordinates are 
properly generated to span the whole window.

In other words I guess that you want to have texcoords match pixel locations 
in the final output screen. Ie you want texcorrds on the objects to 
span -1..1x-1..1 range on the output window. Right ?

If yes, then you could use simple shader, or add a texgen node to produce 
proper texcoords for the output scene. This texgen should use EYE_LINEAR 
coords and its transform should be set to projection matrix of RTT camera 
and main camera.

I am also not sure if seeting your effect camera to RELATIVE_RF gurantees 
using the same projection for RTT camera as for main camera. One could be 
sure if he forces this explicitly
eg:
    camera->setProjectionMatrix( 
viewer->getCamera()->getProjectionMatrix() );

To add texgen node try adding following lines to your code:

    camera->setProjectionMatrix( 
viewer->getCamera()->getProjectionMatrix() );

    osg::TexGenNode * texGenNode = new osg::TexGenNode;
    _scene->addChild( texGenNode );
    texGenNode->setTextureUnit( 0 );
    texGenNode->getTexGen()->setMode( osg::TexGen::EYE_LINEAR );
    texGenNode->getTexGen()->setPlanesFromMatrix
    (
        camera->getProjectionMatrix() *
        osg::Matrix::translate(1,1,1) *  // remap -1..1x-1..1 range
        osg::Matrix::scale(0.5,0.5,0.5)  //  to 0..1 x 0..1 range
    );

One final note, it looks like you use cow.osg model. AFAIK this model 
already contains texgen using SPHERE mapping mode. To avoid conflicts for 
tests I suggest you use other model.

Hope it helps, and no guarrantees,   I have no time to verify if everything 
what I wrote is 100% correct.

Cheers,
Wojtek

----- Original Message ----- 
From: Mathieu Schoutteten
To: osg-users at lists.openscenegraph.org
Sent: Thursday, June 12, 2008 4:35 PM
Subject: Re: [osg-users] [Depth Buffer rendering]


i post my source code for more clarity.. Maybe someone already try to have 
the same effect.
DepthBuffer.cpp include a main method for test.




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