Re: The big divide - graphics contexts and window servers

[Jeff Teunissen]

"Philippe C.D. Robert" wrote:

> On Sun, 17 Mar 2002, Jeff Teunissen wrote:
> <snip>
> > > The only problem is that it doesn't natively handle fonts, which is
> > > really important. There are libraries that add this capability to
> > > OpenGL, but the best ones are written in C++, which means I'll have
> > > to write some cumbersome wrappers (ok, NOW I want Objective-C++!).
> >
> > It's not that OpenGL doesn't handle fonts -- it's that it doesn't
> > handle text at all. This isn't a bad thing, you just have to _want_ to
> > reinvent the wheel.
> 
> Not if you use an existing solution for that purpose...

...but they all SUCK! :)

> > To get "fonts" in OpenGL, you draw them. Not a problem, but you need a
> > font renderer to do it, and then you get to decide what resolution you
> > want to upload it at, you get to upload the texture for each glyph (at
> > whatever point size you want) and display it manually.
> 
> Well, there are libs which allow you to render True Type Fonts AFAIK.

Yes, hence the "Not a problem, but you need a font renderer to do it, ...".
FreeType would probably be used here to render to textures.

> > OpenGL is designed for 3D, and it's not happy with 2D. Most GL
> > implementations don't accelerate 2D operations beyond throwing a quad
> > on the screen, and some even leave it incomplete.
> 
> Uh? Where do you get that from? In GL there is no destinction between 2D
> and 3D.Or do you mean imaging extensions? They are not part of core GL
> anway - which will change for 2.0 though.

No, I'm not talking about the imaging extensions. I mean things like putting a
textured, alpha-blended quad on the screen. I know GL implementations that
screw even THAT up.

> > Also throw in the fact that on most non-professional
> > implementations/cards, you can only have one direct-rendering window
> > at a time.
> 
> I dunno about DRI or NVidias solutions for that, so if you know more (
> as it seems ), please elaborate on that a little, I am very
> interested!...:-)

Most GL drivers on the PC only allow one context to go direct.

> But you are right in that on other systems than Linux, GL acceleration
> is not handled very well ( AFAIK BSD for example ).
> 
> > For anything beyond games and professional or scientific graphics
> > systems, OpenGL is rather a joke.
> 
> Uhm, why do you say so? Take Mac OS X, they use accelerated GL for Aqua
> more and more - do you call that a joke?

Actually, yes, but there's no need to get into that here.

> > Oh...where'd you get the idea that OpenGL did antialiasing at all? It
> > doesn't, that's beyond the scope of the specification.
> 
> No, but most graphics cards/GL drivers do handle anti aliasing.

Yes, but not generally under program control, and not portably.

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