Hi all,
I apologize in advance for the "wordy" post!
I've recently ventured down the path of learning about the use of PBO's in
GL. I've come to
the conclusion that we could probably use this functionality in some of our
texture-based pipelines.
Anyway, I've run into an issue when trying to use them with 3D textures and
I think it's just because
3D textures aren't used nearly as much as 2d textures in this community(at
least until recently!).
I think the problem we're facing is that currently,the PixelBufferObject
class only updates based on data set to an osg::Image.
However, for our 3D texture pipelines, we update our textures via a
subloadcallback. We eventually call
glTexSubImage3D to update the texture data with external data similar to
below:
*void cfdUpdateTextureCallback::subload( const osg::Texture3D& texture,
osg::State& state ) const
{
if( !textureDataHolder )
{
return;
}
if( **textureDataHolder**->TimeToUpdateTextureData() )
{
texture.getExtensions( state.getContextID(), false
)->glTexSubImage3D( GL_TEXTURE_3D,
0,
0, 0, 0,
_textureWidth,
_textureHeight,
_textureDepth,
GL_LUMINANCE_ALPHA,
GL_UNSIGNED_BYTE,
( unsigned char* )**textureDataHolder**->GetTextureData()
);
}
}
}
*I looked at osg::Texture::applyTexImage2D_subload for an example of how to
use PBO's with textures and implemented this in
my subload callback but my data only displays the original image data.
Looking in the function for PixelBufferObject::compileBuffer,
I found that the buffer data is only updated on the data in the image that
the PBO is associated with.
Sooooo...how do I update the image data or the PBO? Ideally, I'd like to be
able to set the data to use for updating the PBO.
We were using the subload callback to manage the data in the texture but now
it seems like
somehow we'll have to manipulate the data in image but I don't see an
interface for that. Am I missing something or has this situation
not been addressed? I have some ideas on how to fix it but they all seem
like a hack so any input/advice there would be greatly appreciated.
biv
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