Merge lp:~gebner/compiz/compiz.vertexbuffer-autoprogram-uniform-segfault into lp:compiz/0.9.9

[Gabriel Ebner]

Adding a uniform to a GLVertexBuffer that uses AutoProgram causes compiz to segfault.

Example:
  gWindow->addShaders("cms", "", fragment_shader);
  gWindow->vertexBuffer()->addUniform("cms_lut", unit);
  // segfault happens later in PrivateVertexBuffer::render

The patch modifies PrivateVertexBuffer::render to set the uniform on the generated AutoProgram instead of the provided program, which in this case is NULL, causing a segfault.

(LP: #1162598)

Adding a uniform to a GLVertexBuffer that uses AutoProgram causes compiz to segfault.

Example:
  gWindow->addShaders("cms", "", fragment_shader);
  gWindow->vertexBuffer()->addUniform("cms_lut", unit);
  // segfault happens later in PrivateVertexBuffer::render

The patch modifies PrivateVertexBuffer::render to set the uniform on the generated AutoProgram instead of the provided program, which in this case is NULL, causing a segfault.

This feature is used in a plugin for full-screen color management, compiz-cms[1], where the unit of a color transformation texture is passed as a uniform.

[1] https://github.com/gebner/compiz-cms

[Sam Spilsbury (smspillaz)]

This makes sense, thanks.

This reminds me that I need to fix the VertexBuffer class to behave in a more sane way when it comes to having no active program set. At the moment it just crashes if you don't call setProgram or setAutoProgram. I remember I wanted to enforce something in its constructor, but at the time didn't want to break ABI. I've filed bug 1162597 about that.

One more thing before we merge this - can you add commit metadata to link this to a bug? I didn't see anything, so I've filed bug 1162598. You can link it by doing this:

bzr commit --empty --fixes lp:1162598
bzr push

On another note, nice work with the color management plugin. If you want it to be included in-tree, just file a bug about it on launchpad and we'll do the paperwork to get it in.

review: Approve

[lp:~gebner/compiz/compiz.vertexbuffer-autoprogram-uniform-segfault]

3645. By Gabriel Ebner on 2013-04-01

(LP: #1162598). Fixes: https://bugs.launchpad.net/bugs/1162598.

[Daniel van Vugt (vanvugt)]

Please re-target this for lp:compiz/0.9.10

review: Needs Resubmitting

Unmerged revisions

3645. By Gabriel Ebner on 2013-04-01

(LP: #1162598). Fixes: https://bugs.launchpad.net/bugs/1162598.

3644. By Gabriel Ebner on 2013-03-31

OpenGL plugin:
Allow uniforms for automatically generated programs in
PrivateVertexBuffer::render.

=== modified file 'plugins/opengl/src/vertexbuffer.cpp'
--- plugins/opengl/src/vertexbuffer.cpp	2012-11-04 16:15:51 +0000
+++ plugins/opengl/src/vertexbuffer.cpp	2013-04-01 06:33:19 +0000
@@ -523,7 +523,7 @@
     // set per-plugin uniforms
     for (unsigned int i = 0; i < uniforms.size (); i++)
     {
-	uniforms[i]->set (program);
+	uniforms[i]->set (tmpProgram);
     }
 
     //convert paint attribs to 0-1 range