View Full Version : xdpyinfo and alpha

09-14-2002, 07:56 AM
I am running RedHat Linux 7.3,
with a GEForce 4.

I am used to running on IRIX machines, where
with xdpyinfo, or similiar programs, you
can get information about the different visual contexts, and their attributes. Such as, 0x21 might have 8 bits of stencil, but not be double buffered, but 0x22 might be the opposite.....

Anyway, IRIX nicely spells it out for you.
Running this under Linux gives you lots
of visual ID's, that seemingly have the same thing???

What I was really trying to get from this was a way to pick the most intelligent visual for my application.

I am trying to do a software antialiasing mode now, that requires the use of
GL_SRC_ALPHA_SATURATE and GL_ONE in the blend function, along with enabling GL_POLYGON_SMOOTH.

The papaer I got this from, said it won't work unless you do a bunch of stuff, and then make sure that your machine can support a visual with "destination alpha".

How can I verify that this is the problem, and not something else? Is there something better than xdpyinfo?



09-14-2002, 10:03 AM
There is the glGetInteger function that you can use to get the number of bits in the alpha plane, but your visual needs to be created first.

You definitly need a 32 bpp for alpha, AFAIK.

I'm not a linux guru, so I cant help further.