I'm assuming that they CopyTexSubImage pixmap content into textures.
This is nothing new. We knew that this works when writing the
GLX_EXT_tfp spec, of course. We actually agreed that CopyTexSubImage is
the appropriate way to handle the case where you have a window that is
larger than the maximum texture size. However, that very rarely happens
so there hasn't been a lot of motivation for adding this fall-back path
to compiz yet.
Using CopyTexSubImage might give similar performance to GLX_EXT_tfp
implementations right now as they are not very optimized yet. However,
CopyTexSubImage will always require a copy operation to get the pixmap
content into a texture and as both a texture and a pixmap need to exist,
the memory consumption is twice the amount that is really necessary.
CopyTexSubImage also requires you to do glXMakeCurrent each time you
need to update a texture, which can be expensive. GLX_EXT_tfp solves all
these issues.
[^] # Re: "Méthode Looking Glass" ?
Posté par gnumdk (site web personnel) . En réponse au journal Metisse dans mandriva!. Évalué à 3.
I'm assuming that they CopyTexSubImage pixmap content into textures.
This is nothing new. We knew that this works when writing the
GLX_EXT_tfp spec, of course. We actually agreed that CopyTexSubImage is
the appropriate way to handle the case where you have a window that is
larger than the maximum texture size. However, that very rarely happens
so there hasn't been a lot of motivation for adding this fall-back path
to compiz yet.
Using CopyTexSubImage might give similar performance to GLX_EXT_tfp
implementations right now as they are not very optimized yet. However,
CopyTexSubImage will always require a copy operation to get the pixmap
content into a texture and as both a texture and a pixmap need to exist,
the memory consumption is twice the amount that is really necessary.
CopyTexSubImage also requires you to do glXMakeCurrent each time you
need to update a texture, which can be expensive. GLX_EXT_tfp solves all
these issues.
-David Raveman