On Wed, 2007-06-06 at 21:06 +0100, Robert Osfield wrote: > Hi Jeremy, > > OpenGL supports texture repeat but only for the whole texture, > osgtexture2D has an example of texture repeat so have a look at whats > possible with just standard OpenGL wrap modes.
C'mon, I at least knew this much! *grin* > Repeating a sub-porton of texture atlas is rather different though, > using wrap modes you'll end up repear over the whole 0.0 to 1.0 range > rather than just the portion you want. If you using a TextMat you can > get OpenGL to repeat the texture at high frequency, but it'll still be > over the whole 0.0 to 1.0 range, it won't skip things out of your > range. > > The only ways I can think of repeating a subporting are to use GLSL to > manage the tex coord wrapping internally in the fragment program, or > to simply repeat your texture manually in your texture atlas, or just > ditch the use of sub regions and wash, rinse, repeat like standard > OpenGL texture wrap modes. Yeah, this is what I suspected. It still kinda' raises the question how other kits do it, but I bet it's something like this: Here's my window's conceptual top bar: +---+------------------------------+---+ | 1 | 1 | 3 | +---+------------------------------+---+ ...and I bet this is theirs: +---+---+---+---+---+---+---+---+---+---+ | 1 | . | . | . | . | . | . | . | . | 3 | +---+---+---+---+---+---+---+---+---+---+ ...where they've created new geometry to accommodate for being unable to tile only a portion of a texture. I think there's a Linux OpenGL tool that will let me force anything being rendered in OpenGL to be in wireframe... I'll snoop a bit and confirm... > Robert. > > > On 6/6/07, Jeremy L. Moles <[EMAIL PROTECTED]> wrote: > > I've tried googling and asking this question in various other OpenGL > > places with no success--so I figured I'd try here, since I know there > > are some OpenGL gurus around. In fact, I was told in #opengl on Freenode > > it wasn't possible, but I doubt it sense people have been doing this for > > ages used fixed-function OpenGL. > > > > I'm working on a UI toolkit using native OSG objects (no weird > > "gluecode" or external library) and have come across something I can't > > readily get the answer to. > > > > Imagine an interface "window"; at the minimum you'll have about 9 > > regions that describe this window: > > > > - upper left and right corners > > - lower left and right corners > > - top, left, bottom, and right "bars" > > - center > > > > Now imagine a texture you want to use as the window's "skin." Ideally, > > you'll load an image into the texture and position the TexCoords so that > > you can create the illusion of having a true, decorated and composed > > window. This is fairly straightforward in concept except for one aspect. > > > > Lets say you want to texture the "top bar" region of your window. Well, > > by default, unless this portion of your image (or skin) is cleverly > > positioned in the texture itself, there's really no way I know of to > > "tile" it across the geometry. You can stretch it across, but this is > > often quite ugly. > > > > My question: is it possible in OpenGL to somehow manipulate the texture > > matrix (or something else) to only operate on a "sub-region" of a > > texture such that you can tile just that portion? CEGUI does this > > somehow, but it's API is so abstracted I can't really track it's > > implementation down. > > > > I _know_ it's possible using a GLSL shader, but at this point it's > > really academic for me to find out how to do it otherwise, I know game > > makers have been doing this for years w/out shaders, and it's really > > bugging me to find out how! :) Any advice or guidance on the issue would > > be enormously appreciated... > > > > _______________________________________________ > > osg-users mailing list > > [email protected] > > http://openscenegraph.net/mailman/listinfo/osg-users > > http://www.openscenegraph.org/ > > > _______________________________________________ > osg-users mailing list > [email protected] > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ > _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
