Re: [Mesa3d-dev] Mesa SOF textrues

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

Andrew Richardson wrote:
> 
> I can't rem if this was originaly posted here or on DRI but...
> 
> If you flush the VB down into the driver (and card) then I have a question.
> I want to show video using ogl as the renderer (cf glmovie from loki). So I
> want to paste multiple textures onto muliple quads. Say I have two textures
> and two quads, I want two texture units to do the texturing, one quad-texture
> each. the code is like
> 
> glClientActiveTextureARB ( GL_TEXTURE0_ARB );

You probably want glActiveTextureARB() here.  glClientActiveTextureARB() is
for selecting vertex array sets.

> glTexture2D(/*texture 0*/);
> glCallList(QUAD0);
> 
> glClientActiveTextureARB ( GL_TEXTURE1_ARB );
> glTexture2D(/*texture 1*/);
> glCallList(QUAD1);
> 
> The second glTexture2D call will flush the VB, but to where?

If there are any queued rendering commands, they'll get executed and retired.

> Does the card
> process all of texture/quad 0's stuff? If so I don't see how I can use both
> texture units at the same time for texture procedures that don't share
> verticies. Of course I may not be implementing the dual text-unit stuff
> correctly but even if Im not the question still stands, what happens with
> multi-texturing when the two (or more) units don't share verticies.

I think you're confused about how multitexture works.  Texture units
don't know anything about vertices.  Each vertex processed has N sets
of texture coordinates associated with it- one set per texture unit.
The application of texture environments is pipelined so all active
units contribute to processing each fragment (pixel).

I don't understand what you're trying to do.


> Also how does Mesa deal with references to GL_TEXTURE~N~_ARB where ~N~ is
> larger than the actual number of tex-units,

Trying to address or enable ~N~ would cause an error and be a no-op.

> does it map them to the texture
> units that ARE present or is it in the ogl spec that it returns an error?

You should read the spec.  It's an error.

-Brian