Merge lp:~3v1n0/compiz/msaa-configs-ignore into lp:compiz/0.9.10

[Marco Trevisan (Treviño)]

OpenGL Screen: Ignore the MSAA configs during initialization

This fixes a crash with new MESA drivers and high monitor resolutions
caused by the fact that we're accidentally using some MSAA configs with
some drivers in Mesa 9.0.
Taking in account the values of GLX_SAMPLES and GLX_SAMPLE_BUFFERS
fixes the issue.

See mesa bug https://bugs.freedesktop.org/show_bug.cgi?id=61182

In some cases compiz opengl plugin uses MSAA configurations while it should not and this is causing a crash when using compiz with big resolutions with recent MESA drivers.

The fix is based on the changes proposed by MESA developers that also Kwin and Clog have recently applied:
 - http://quickgit.kde.org/?p=kde-workspace.git&a=commitdiff&h=6cf057777555
 - https://git.gnome.org/browse/cogl/commit/?id=93b7b4c850

[MC Return (mc-return)]

LGTM.

review: Approve

[Sam Spilsbury (smspillaz)]

This is fine as we don't need msaa for tfp operations.

Can you (doesn't have to be in this branch)

1. Add this to the egl configs too (eg, http://www.khronos.org/registry/egl/sdk/docs/man/xhtml/eglChooseConfig.html EGL_SAMPLE_BUFFERS and friends)
2. Use compiz variable naming conventions e.g. msaaBuffers as opposed to msaa_buffers

review: Approve

[lp:~3v1n0/compiz/msaa-configs-ignore]

3699. By Marco Trevisan (Treviño) on 2013-05-13

GLScreen: use compiz names convention

[Marco Trevisan (Treviño) (3v1n0)]

Updated variable names. EGL changes in a new branch.

[PS Jenkins bot (ps-jenkins)]

review: Approve (continuous-integration)

=== modified file 'plugins/opengl/src/screen.cpp'
--- plugins/opengl/src/screen.cpp	2013-01-09 10:57:03 +0000
+++ plugins/opengl/src/screen.cpp	2013-05-13 15:58:25 +0000
@@ -1058,7 +1058,7 @@
 
     for (i = 0; i <= MAX_DEPTH; i++)
     {
-	int j, db, stencil, depth, alpha, mipmap, rgba;
+	int j, db, stencil, depth, alpha, mipmap, msaaBuffers, msaaSamples, rgba;
 
 	priv->glxPixmapFBConfigs[i].fbConfig       = NULL;
 	priv->glxPixmapFBConfigs[i].mipmap         = 0;
@@ -1066,11 +1066,13 @@
 	priv->glxPixmapFBConfigs[i].textureFormat  = 0;
 	priv->glxPixmapFBConfigs[i].textureTargets = 0;
 
-	db      = MAXSHORT;
-	stencil = MAXSHORT;
-	depth   = MAXSHORT;
-	mipmap  = 0;
-	rgba    = 0;
+	db          = MAXSHORT;
+	stencil     = MAXSHORT;
+	depth       = MAXSHORT;
+	msaaBuffers = MAXSHORT;
+	msaaSamples = MAXSHORT;
+	mipmap      = 0;
+	rgba        = 0;
 
 	for (j = 0; j < nElements; j++)
 	{
@@ -1146,7 +1148,21 @@
 	    depth = value;
 
 	    (*GL::getFBConfigAttrib) (dpy, fbConfigs[j],
-	                              GLX_BIND_TO_MIPMAP_TEXTURE_EXT, &value);
+				      GLX_SAMPLE_BUFFERS, &value);
+	    if (value > msaaBuffers)
+	        continue;
+
+	    msaaBuffers = value;
+
+	    (*GL::getFBConfigAttrib) (dpy, fbConfigs[j],
+				      GLX_SAMPLES, &value);
+	    if (value > msaaSamples)
+	        continue;
+
+	    msaaSamples = value;
+
+	    (*GL::getFBConfigAttrib) (dpy, fbConfigs[j],
+				      GLX_BIND_TO_MIPMAP_TEXTURE_EXT, &value);
 	    if (value < mipmap)
 		continue;