Re: "floccinaucinihilipilification", or "convolutions, blocking, and windows server 2003"

So much for the job thing.  Showed up to work to find myself no longer
having one, heh.

> Is the interface you're currently using for Xrender final, or is it
> likely to change? If it's final, it would be kind if you could save me
> some time and shortly describe the convolution interface (functions,
> function parameters ...). libglc is currently using a simple interface
> similar to the Transform interface of Xrender. Setting a convolution
> kernel for a surface will currently make libglc perform convolution on
> that surface when it's used as source in a composite operation without
> modifying the original surface

I should have done my research better - if I'd known that there was already
an implentation of this, I would have just copied that :).  But anyhow.

How this works as implented right now:

XRenderCreateConvolution() creates a convolution, and takes a bunch of
parameters, those being:

	- op (which operation to perform.  There is a list of these, all
	      of which are matrix ops, but they could be anything)
	- wrapType (WrapNone, WrapClamp, WrapRepeat - think opengl texture wrapping)
	
	it then takesfour divisors for matricies, an xsize and a ysize, and four
	matricies (of these, all are optional depending on the op - for the
	desaturate op, they're all NULL.  for the blur op, you only set
	xsize and ysize).  This should be cleaned up, though, perhaps passing
	a structure instead.

.From there, there are two methods for using this convolution:

XRenderExecuteConvolution() will execute it on a specific area.  I use this to
implent "blur under transparent window", for example, where I place the data
to be displayed under the window, execute the convolution on the window area, 
and then place the transparent window. (no screenshot of this, use your 
imagination :))

XRenderAddConvolution() will add a convolution to a picture.  A picture can have
an arbitary number of convolutions attached to it, an example of this is that
in my shadow drawing code (http://www.dspaudio.com/~jaymz/shadow12.png), I have
a desaturate and a blur attached to each shadow image, and the xserver just
magically applies those.

One thing which I havn't implented yet, is the API to reorder the convolutions
attached to a picture, mostly because I havn't yet found a set of semantics 
for this which I find appealing.  There is an XRenderRemoveAllConvolutions()
in my tree, which I just stopped from randomly crashing about, uhm, three 
minutes ago, so I'll upload a tarball with that in it later.

	-- jj

p.s. i cc'd this mail to [email protected], since the explanation of how it works 
is probably useful to anyone daring to look at the steaming pile :)

-- 
Jaymz Julian - Coder, Visionary, Fat Ass.
"Hannibal is a serial killer. He only likes to kill and eat people. 
 Very few people have `I want to be killed and eaten' on their cards, 
 so Hannibal is out of a job." - http://cards.sf.net