Re: [Mesa3d-users] Alpha blending

[Brian P. <br...@va...>]

Gian Paolo Lorenzetto wrote:
> 
> Hi all,
> 
> I'm trying to draw a scene containing an arbitrary number of
> semi-transparent polygons, as well as several solid objects. The
> solid objects I have placed in a display list, and if all the
> trasparent polygons have the same alpha value, things work OK (although
> there is a noticable change in the brightness of solid objects when the
> transparent objects are added to the scene - this may be somethign I'm
> doing wrong with the lighting/material properties, I really don't know).
> 
> My real problem comes when I change one of the transparent objects to
> solid (or near solid) - this causes ALL the transparent objects to become
> solid. If the solid object is removed from the scene the transparent
> objects are once again displayed correctly.
> 
> I'm using glMaterial* to set the colour and alpha values, and using a
> blend func of
> 
> glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
> 
> I've checked the red book, and I _think_ these paramters are what I'm
> after.
> 
> Any help would be greatly appreciated. I haven't included source for
> brevity, but if it would be helpful I can send it to you (it's basically
> glutskel.c from the Mesa 3.4 utils dir, with some additions :).

I'll take a look at it.  Just send it to me.

-Brian