-
`ClutterOffscreenEffect` had been getting the wrong bounding box in the case of clones and descendents of clones, causing visibly incorrect clipping. This was due to `clutter_actor_get_paint_box` only ever being given the source actor during a paint (which is correct) and not the clone. Even if we weren't painting a clone but an offscreened descendent of a clone (like in gnome-shell's desktop zoom), we would get the wrong result. Fortunately we don't need to know the actual clone/actor being painted so don't need to call the problematic `clutter_actor_get_paint_box` at all. The solution is to only keep untransformed rendering in the FBO and leave the correct transformation for later. The correct clone/actor's transformation is already set for us as the current cogl modelview matrix by `clutter_actor_paint`. Bonus optimization: This all means we don't need to keep `last_matrix_drawn` or force a full repaint every time some part of the transformation changes. Because the FBO contents are no longer affected by transformations. As it should be. In other words, offscreen-effected actors can now move around on screen without themselves being repainted. Special thanks to Mai Lavelle for identifying the cause of the problem. Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=789050, https://bugzilla.gnome.org/show_bug.cgi?id=659523#c9, #196, #282, gnome-shell#387, https://launchpad.net/bugs/1767648, https://launchpad.net/bugs/1779615
8655bc5d
