Basic Blur

[mikedee]

This is another very old Compiz plugin which I found in my tmp dir.

I have patched it to work with current compiz, there is a problem with the GL code somewhere as it doesnt actually blur anything. Maybe I was just compiling it wrongly.

If anyone fancies having a go at making this work I would be grateful :) It is fairly simple to get to grips with so would be ideal for someone who wants to learn.

I cannot remember how this plugin originally worked so whoever fixes it will see :)

http://www.anykeysoftware.co.uk/compiz/plugins/basicblur.tar.gz

I originally added these lines to the addScreen function (as well as compiz.h) and it didnt crash so I assume it was OK. This is how compiz deals with these functions.

if (strstr (glExtensions, "GL_ARB_imaging"))
{
s->convFilter2D = (GLConvolutionFilter2DProc)
getProcAddress (s, "glConvolutionFilter2D");
s->convParameteri = (GLConvolutionParameteriProc)
getProcAddress (s, "glConvolutionParameteri");
}

[julio]

Hello,
I did write this plugin ;)
It is loosely based on the neg plugin. When toggling "Blur screen" you should for example get something like this :
http://ghanima.alarue.net/albums/compiz/Screenshot_11.thumb.png (http://ghanima.alarue.net/gallery/compiz/Screenshot_11)

The version you used is a very old one that did not work well. I think I posted a more efficient version on the compiz-quinn forums a long time ago.
I should have it somewhere, I'll look for it when I get back home after work ;). I don't know if it is very usefull (but we can imagine other Convolution filters and this can become funny - the bad point is that this is not accelerated by the card :(), but you are right this was a very simple example to learn how plugins work.

[mikedee]

Cool - thanks very much :)

I think we could speak with David about making it work for blurring under windows. It should be possible to get the compositor to help with under window effects.

[julio]

My bad.
This is actually the last version I have...
What "does not work" ? What happens when you toggle the action key ? (something like Super+b I think) ?
It's been a while since the last time I compiled compiz, I may have time to test it tonight, but I'm not sure. I'll keep you updated.

On a side note, this is a blur that does not use shaders, but 1/ it's slow though usable (multiplicating two 1D filters should be faster without any noticeable difference) 2/ it works only before a glCopy or glDraw operation. That means that you will probably need to duplicate some texture if you want to blur under a window (because it has already been rendered)...

[mikedee]

When I toggle the window key, it doesnt go blurry. There is a sligh flash but nothing else :(

[julio]

Ok, I compiled it here, and I've got the same (no blur)
Note that I don't use the same graphic card : I have an ATI Mobility Radeon X1600 here, and I made my tests on an old gf4 back in the days...
Some debug is needed...

[julio]

Ok I tracked down the problem.
glEnable(GL_CONVOLUTION_2D); generates a GL_INVALID_ENUM error.
Now I realize that glxinfo does not give me any GL_ARB_imaging extension, meaning that convolution filters are not available.
The question is: Why did it work on my gf4 + Xgl ?
And of course, how make it work (GL_ARB_imaging extension is here in the underlying Xorg server) ? Or am I (probably) missing something ?

[mikedee]

Ok I tracked down the problem.
glEnable(GL_CONVOLUTION_2D); generates a GL_INVALID_ENUM error.
Now I realize that glxinfo does not give me any GL_ARB_imaging extension, meaning that convolution filters are not available.
The question is: Why did it work on my gf4 + Xgl ?
And of course, how make it work (GL_ARB_imaging extension is here in the underlying Xorg server) ? Or am I (probably) missing something ?

I do not know where this extension comes from - I use nVidia beta drivers and xorg 7.1 and I have it listed.

There were some patches to compiz-quinn so that this plugin could work (I think?), there are some setup functions for these gl functions although I do not claim to know why they are needed.

If you are really stuck, a post on the mailing list will probably sort things out :)

[julio]

I should always verify before saying idiotic thing :)
I don't have any GL_ARB_imaging on my radeon... I did not think this was this rare... This extension is present on my gf4 though. I don't see any other way to make a real blur not too cpu demanding :(
Could you check if you have an error too when you call glEnable(GL_CONVOLUTION_2D);
with :
GLenum rc = glGetError();
if(GL_INVALID_ENUM == rc)
printf("Invalid Enum\n");
Before and after the call ?

[mikedee]

There is nothing output with that extra code.

When I compile it I get these warnings, I am not sure if the makefile needs to be changed or if each of these needs to be loaded by compiz first (as for the other GL functions).

basicblur.c: In function `basicblurDrawWindowTexture':
basicblur.c:154: warning: implicit declaration of function `glConvolutionFilter2D'
basicblur.c:155: warning: implicit declaration of function `glConvolutionParameteri'