[Mesa3d-dev] Callbacks/API hookouts vs. NEW_* flags

[Keith W. <ke...@va...>]

Brian,

I've been thinking about this a little bit & it seems to me there will always
be good reason to keep both of these state update mechanisms around. 
Additionally, by extending the use of the _NEW_ flags we can overcome a couple
of uglinesses in the current code base.

We've talked about this before and I'd said that my position was roughly:

	- Callbacks (to be replaced/augmented by API hookouts) are the mechanism for
keeping the hardware driver uptodate
	- _NEW_ flags are used 
		- to wake up things like the software rasterizer or t&l mechanism after
being put to sleep
			- a large amount of state may have changed without any other notification
		- to keep those components uptodate during normal operation
			- this is the current gl_update_state mechanism, split up between core,
rasterizer and t&l

The two uses for the _NEW_ flags can be handled by the same code -- the only
difference is the amount of state that might have changed.

To this I'd like note another use for the _NEW_ flags:  to notify the driver
itself after a very large state-change, when using callbacks would be
cumbersome.  The obvious example of such a state-change is in glPopAttrib(). 
Rather than attempting to call callbacks for every piece of state in an
attribute, consider adding:

	ctx->Driver.NotifyStateChange( GLcontext *ctx, GLuint newstate )

or, for consistency:

	ctx->Driver.Wakeup( GLcontext *ctx, GLuint newstate )

which can be called in these cases.  The driver would be expected to know
enough about it's internal state to handle this event.

Keith