[osg-submissions] 2D Array Textures (EXT_texture_array for osg)

[Robert Osfield]

Hi Art,

I have now merged and submitted your changes to SVN.

I had to add an extension check to Image.cpp to protect the check
against the image enable otherwise this will generate and GL error on
non 8 series class hardware.

Modifications to prevent apply texture array when using fixed function
pipeline is not required as users can only access texture arrays from
shaders, if they aren't using shaders then won't (if they know what
they are doing) attach texture arrays.  Its a bit like attaching
Uniforms - one simply doesn't attach them if you don't need them.
Also trying to implement such nanny approach to prevent some users
from apply state inappropriately would be add complexity, slow the OSG
down all for avoiding a problem that is really is a case of garbage in
garbage out - we don't want to penalize the competent because others
less competent might screw up.

I haven't yet been able to test the new class, so an example that
tests it out would be very welcome.  Also still missing is .osg and
.ive support for the new Texture2DArray.  I also wonder if one might
be able reuse more of the Texture3D implementation in the
Texture2DArray implementation, as alot of the code is common.

Robert.

On 7/24/07, Art Tevs <stud_info2 at yahoo.de> wrote:
> Hi Robert,
>
> OK, thanks.
>
> P.S. As soon as you get the G80 you will love it ;-)))
>
> --- Robert Osfield <robert.osfield at gmail.com> schrieb:
>
> > Hi Art,
> >
> > I don't yet have a 8800, so can't yet test any of
> > the new extensions.
> > I have an 8800GTS on order and when it arrives and I
> > have a quiet
> > spell I'll sit down review the extension docs and
> > your submissions.
> > Right now I can't test or know enough about the new
> > extensions to
> > attempt a review.
> >
> > I might be a week or so before I can get this
> > review.
> >
> > Robert.
> >
> > On 7/24/07, Art Tevs <stud_info2 at yahoo.de> wrote:
> > > Hi folks, Hi Robert.
> > >
> > > Here is my submission for the osg. Description:
> > >
> > >
> > ----------------------------------------------------
> > >
> > > A new texture class Texture2DArray derived from
> > > Texture extends the osg to support the new
> > > EXT_texture_array extensions. Texture arrays
> > provides
> > > a feature for people interesting in GPGPU
> > programming.
> > >
> > >
> > > Faetures and changes:
> > >
> > > - Full support for layered 2D textures.
> > >
> > > - New uniform types were added (sampler2DArray)
> > >
> > > - FrameBufferObject implementation were changed to
> > > support attaching of 2D array textures to the
> > > framebuffer
> > >
> > > - osgUtil/RenderState is changed to enable render
> > to
> > > texture mode for array textures.
> > >
> > > - StateSet was slightly changed to support texture
> > > arrays. NOTE: array textures can not be used in
> > fixed
> > > function pipeline. Thus using the layered texture
> > as a
> > > statemode for a Drawable produce invalid enumerant
> > > OpenGL errors.
> > >
> > > - Image class was extended to support handling of
> > > array textures
> > >
> > > Tests:
> > > I have used this class as a new feature of my
> > > application. It works for me without problems
> > (Note:
> > > Texture arrays were introduced only for shading
> > > languages and not for fixed function
> > pipelines!!!).
> > > RTT with Texture2DArray works, as I have tested
> > them
> > > as texture targets for a camera with 6
> > layers/faces
> > > (i.e. replacement for cube maps). I am using the
> > array
> > > textures in shader programming. Array textures can
> > be
> > > attached to the FBO and used as input and as
> > output.
> > >
> > > Must be done:
> > > - Restrict user to bind an Texture2DArray to any
> > > "Geode" (i.e. by setting up StateSet), such that
> > they
> > > can not be used for fixed function pipeline.
> > Probably
> > > a warning should be ok, when user call
> > > osg::StateSet::setTextureAttributeAndModes(0,
> > > texture2Darray, osg::StateAttribute::ON); with
> > > texture2Darray as an instance of Texture2DArray
> > class.
> > >
> > >
> > > Should be done:
> > > - Adding of Texture1DArray class.
> > > - Support for integer texture EXT_texture_integer
> > >
> > >
> > >
> > ----------------------------------------------------
> > >
> > > Since I am working on an Shader Model 4.0
> > application,
> > > I will probably make more contributions to the
> > osg,
> > > which implements the new extensions. I was not
> > able to
> > > find out, if some one already working on them :-(
> > Next
> > > one is the EXT_geometry_shader4 and
> > EXT_gpu_shader4.
> > >
> > > Thanks.
> > >
> > > Cheers, Art
> > >
> > > P.S. Please let me know if you add this
> > contribution
> > > to the svn or not. This would be very helpfull for
> > > future developments.
> > >
> > >
> > >       __________________________________  Alles
> > was der Gesundheit und Entspannung dient. BE A
> > BETTER MEDIZINMANN! www.yahoo.de/clever
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> > >
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