Re: opengl and images

[Shai Ayal]

On Tue, Oct 6, 2009 at 12:20 AM, Michael D. Godfrey
<address@hidden> wrote:
> It is known that OpenGL has various errors depending on
> drivers, etc.  Here is what you get if you type opengl('info')
> in  M:
>>> opengl('info')
>
> Version         = 1.4 (2.1.2 NVIDIA 185.18.36)
> Vendor          = NVIDIA Corporation
> Renderer        = GeForce 6200 TurboCache(TM)/PCI/SSE2
> MaxTextureSize  = 4096
> Visual          = 0x21 (TrueColor, depth 24, RGB mask 0xff0000 0xff00
> 0x00ff)
> Software        = false
> # of Extensions = 79
>
> Driver Bug Workarounds:
> OpenGLBitmapZbufferBug    = 0
> OpenGLWobbleTesselatorBug = 0
> OpenGLLineSmoothingBug    = 0
> OpenGLClippedImageBug     = 1
> OpenGLEraseModeBug        = 0
>

Maybe the "OpenGLBitmapZbufferBug" is the problem we are seeing here,
but I'm not sure.
Superficially reading thee opengl docs I don't see anything to suggest
that what we are seeing is a bug in the driver, but I can't see
anything to suggest that isn't either ...

To workaround this in the opengl-renderer would mean to use textures
for images. This is complicated since textures have maximal size and
are limited to powers of two in their dimensions.
Another workaround is to use surface objects for images.
Yet another workaround is to use mesa software rendering. In debian,
this worked for me:
apt-get install libgl1-mesa-swx11-dev libgl1-mesa-swx11-i686
However, this will disable opengl hardware acceleration, which might
be a high price to pay.

Shai