Qtopia coming for Neo1973

thomas.cooksey at bt.com thomas.cooksey at bt.com
Thu Sep 20 05:57:48 CEST 2007

>After the docs come out, it should be possible to write a Mesa driver
>right?  My impression is OpenGL ES is just a subset of regular OpenGL;
>it's not so different that Mesa APIs would not work.  Then the whole
>X/GLX/Mesa/driver/DRI stack could be used.

Writing a 3D graphics driver is a big project, but I guess it is possible if the docs are avaliable. I spoke to Zack Ruskin a few weeks ago about adding OpenGL ES support into Mesa. From the very brief conversation we had he seemed to think that it wouldn't be too difficult. The main difference between OpenGL and OpenGL ES (apart from the greatly reduced set of operations) is that OpenGL ES only accepts fixed-point data types. Zack was saying that for speed reasons, large portions of the Mesa paths are implemented as fixed point already.

>I think XRender does take advantage of whatever acceleration the X
>driver implements.

>From what I've read, the X.org XAA does a very bad job of allowing XRender to be accelerated and was one of the reasons why X.Org has a new video driver model. I assume KDrive uses it's own driver API which isn't hampered by limitations of XAA?

>If there is offscreen memory, bitmap glyphs for the fonts that you are
>using can be cached

Surely offscreen pixmaps can also be accelerated, I.e. a pixmap based theme engine would be greatly accelerated?

>I'd like to see accelerated Bezier curves too, but not sure if that's possible.

XLib doesn't do Beizier curves, only arcs, so there's nothing to accelerate in the X server. Bezier curves have to be rendered client side (Unlike Qtopia).

>I think for the ultimate in eye candy, using OpenGL pretty directly
>with as few layers as possible between your OpenGL app and the
>hardware would be the way to go.  (I'm pretty sure that's what Apple
>does.)  But OpenGL doesn't do windowing, so you either have to write
>some new windowing code or depend on X to manage that part, or just
>run every app full-screen.  And almost every idea along these lines
>has some sort of implementation out there somewhere already... like
>Fresco, for example.

Qtopia already has a nice light-weight windowing system - QWS. What's more (as I've mentioned already) I believe all windows can be rendered into texture memory and composited just like Compiz/Beryl. I'm currently trying to get Mesa Solo working so I can have a go at writing an OpenGL driver for Qtopia (For Samsung Q1 type devices really).

>I'm having some fun working directly with /dev/fb0
>and making sure I understand what I'm writing from the bottom up.

I too like to understand how everything works from the bottom up. :-) I guess that's another reason I liked Qtopia - because the documentation is just so good!
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