Hi Tim, I haven't yet looked at the submission so can't comment too much on the approach. I was a bit surprised that that it was a StateAttribute approach, as I was expecting something more closely aligned to the current osg::Uniform support.
However, I'm not too familiar with the uniform blocks so I wouldn't worry about my own expectations too much - I will have to dive into the OpenGL feature, your submission and gets some hardware+drivers that support uniforms blocks to learn about them myself. Now that NVidia have released a well balanced Fermi card I'll be upgrading to get myself some fully capable hardware, then I'll just have to work on the other distractions... At my end I'm juggling a couple of different tasks, some client work improving 3D text support, shader composition and family commitments - it's school holidays now so lots days out of the office. Unfortunately this does mean that I don't have many slots available to dive into other topics. So if you feel comfortable with the approach your taking go for it, I'll try to get back and review the changes as soon as I can. Thanks for you patience, Robert. On Thu, Jul 15, 2010 at 9:30 AM, Tim Moore <[email protected]> wrote: > Hi Robert, > I'm wondering if you've had any chance to take a look at this submission. I > know that you're heads-down in shader composition and probably don't want to > want to think about any large submission, especially one that touches state > management. However, this doesn't touch State, StateAttribute etc. in any > fundamental way. I ask because I'm thinking of going forward in two > directions with this: filling in the missing features, and using the same > approach to support transform feedback buffers. Do you have any comments on > the basic approach? > Thanks, > Tim > > On Wed, Jun 30, 2010 at 9:07 AM, Tim Moore <[email protected]> wrote: >> >> Hi, >> Here is initial support for uniform buffer objects. The binding between a >> buffer object and an indexed target is implemented as a new StateAttribute, >> UniformBufferBinding. I've included an example program based on the code in >> the ARB_uniform_buffer_object specification. >> A few things remain to do: >> * The binding between a uniform block in a shader program and a buffer >> indexed target number is fixed, like a vertex attribute binding. This is too >> restrictive because that binding can be changed without relinking the >> program. This mapping should be done by name in the same way that uniform >> values are handled i.e., like a pseudo state attribute; >> * There's no direct way yet to query for the offset of uniforms in uniform >> block, so only the std140 layout is really usable. A helper class that >> implemented the std140 rules would be quite helpful for setting up uniform >> blocks without having to link a program first; >> * There's no direct support for querying parameters such as the maximum >> block length, minimum offset alignment, etc. Having that information >> available outside of the draw thread would make certain instancing >> techniques easier to implement. >> Tim > > > _______________________________________________ > osg-submissions mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org > > _______________________________________________ osg-submissions mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
