On Mon, Dec 15, 2003 at 07:43:39AM -0600, Stephen J Baker wrote:
> But that assumes that alpha is pre-multiplied into the RGB's - which is
> not the case for either DirectX or OpenGL's hardware texturing.
Both OpenGL and DirectX can handle premultiplied alpha just fine. Just use
additive blending and off you go. :-)
The problem is of course that you lose a lot of precision when everything has
to be stored in 8-bit-per-channel bitmaps after the multiplication.
> The standard OpenGL MIPmap generator does not do as you suggest it should.
There is no "standard OpenGL mip-map generator". gluBuild2DMipMaps is a part
of the GL Utility kit (GLU), not OpenGL, and it usually does its work in
software anyhow (quite slowly, and with mediocre quality). You have an OpenGL
extension (GL_SGIS_mipmap_generate IIRC) that does automatic filtering, but
the exact filtering method is somewhat undefined.
/* Steinar */
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