On Tue, 11 Jun 2002, Billy Biggs wrote:
> Detlef Grittner ([EMAIL PROTECTED]):
>
> > I've recently found out that NVidias Geforce2 does bilinear
> > Interpolation when scaling up and some linear interpolation when
> > scaling down images with DirectX on Windows.
> > I want to know whether that is a hardware feature?
> > Can I use XFree86 and have the same interpolation when using
> > XShmPutImage? Which drivers for Nvidia cards will provide the
> > interpolation?
> >
> > And do cards of other vendors have the interpolation and can I use it
> > with XFree86?
>
> With the texture engine in most cards these days you can get happy 2d
> R'G'B' scaling, and apparently some new cards can do gamma-correct
> scaling (woohoo!). Hardware scaling is useful for emulators especially
> so you can get nice fullscreen modes without having to convince your
> monitor to get back to 320x240, and without hurting your CPU.
>
> I hacked the mga driver here to provide RGB surface scaling (565)
> using the XVideo API. I'd like to see more drivers export RGB surface
> scaling using XVideo- this seems to be the right interface for it. I
> haven't yet got a nice patch for my work done though, and I'm waiting
> for the 4.2 debian packages to help with doing a patch for 4.2.
>
> I hear that some other drivers (ati?) are exporting RGB surfaces
> already using XVideo. I hope this continues, and that we can
> standardize on what fourcc's we should use.
NVIDIA's binary drivers offer an 8:8:8:8 XRGB surface via
X-video.
>
> In windows this functionality is exported transparently using
> DirectDraw/StretchBlt. I think XVideo is probably the best API to
> extend on the linux side.
It depends what you want to do with it. In the case of
NVIDIA's binary drivers these do not use the overlay for RGB,
but if some drivers do, it's not really useful for much other
than video. I think it would be a mistake to write an application
that relies on blitted (not overlaid) RGB Xv support unless you
only wanted to target a particular hardware platform.
For the general case, you're really much better off using
OpenGL, which is guaranteed to support this.
Mark.
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