[osg-users] Render to texture memory usage

[Martin Aasen]

Hi,

I am rendering to a texture using a FBO:

camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
camera->attach(osg::Camera_COLOR_BUFFER, texture, 0, 0, false, 0, 0);

The consumption of GPU memory is about three times higher than I would expect: about 800 MB for a 8192 x 8192 GL_RGBA texture.

Is this due to allocation of a depth buffer and others?

I don't need depth testing so that could be disabled, but I don't understand how to... I was hoping that the memory consumption of the texure was all that was needed.

Any help is much appreciated!

Cheers,
Martin

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[Wojciech Lewandowski]

Hi,

Multithreading modes allocate two instances of OpenGL resources to speed up
rendering .
Default implicit buffer attachment policy adds depth buffer to FBOs if only
color buffer was attached.

Try running your app in SingleThreaded mode with Camera
implicitBufferAttachmentRenderMask set to zero.

Cheers,
Wojtek

[Martin Aasen]

Thanks Wojciech,

By setting the mask the memory usage was reduced to just over 300MB.

Martin

------------------
Read this topic online here:

http://forum.openscenegraph.org/viewtopic.php?p=27582#27582