User Agent: Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.2 (KHTML, like Gecko) Ubuntu/11.10 Chromium/15.0.865.0 Chrome/15.0.865.0 Safari/535.2 Steps to reproduce: using the webpage in the zip Actual results: It display a plane and a green cube on chrome. If you move the mouse to change the camera it looks normal. On firefox I see a green cube but not the plane and when I change the camera with the mouse, there is a kind of z bug Expected results: It should work like in chrome meaning viewing green cube with the plane.

This was obtained by editing osg-debug.js to comment out the requestAnimationFrame call to draw only one frame. Firefox renders a gray frame, no green cube.

Chrome renders the scene with the green cube.

generated by: egrep -i draw\|clear\|depth\|buffer firefox-trace-trigrou | egrep -v EXTENSIONS\|glX > firefox-simple

egrep -i draw\|clear\|depth\|buffer chrome-trace-trigrou | egrep -v EXTENSIONS\|glX > chrome-simple

Right at the beginning, Firefox does glClearDepth(1) while Chrome does glClearDepth(0). That would explain it.

Drawingbuffer default values are described here: http://www.khronos.org/registry/webgl/specs/latest/#2.2 Renderbuffer default values are described here: http://www.khronos.org/registry/webgl/specs/latest/#4.1 in both cases, the default value of depth is 1, not 0. -> Chrome bug.

Current WebKit sources look fine, and the script does call clearDepth, so this seems to be a red herring. Still CC'ing Gregg as there might be a performance issue if WebKit is uselessly clearing the depth buffer with zero value.

Further investigation: * the difference between the clear-calls between firefox and chrome comes from the fact that firefox clears the whole drawingbuffer and then remembers that it's cleared and that the clear-values are the default values so that it skips subsequent clear-calls. * reloading the page in firefox makes it work, and putting a alert() before the clear() call also makes it work, so there must be a firefox bug.

Possibly related: bug 677543

Almost certainly a dupe of 677543. Patch coming there. Will dupe when i'm 100% sure.

Any workaround ? I tried to use a gl.clearColor(0.01, 0.01, 0.01, 0.01) and gl.clear(allbits) at the begining of the frame but it does not help. Any hints ?

As discussed with Cedric: he was relying on gl.clear not being affected by gl.depthmask. The GLES 2.0.25 spec page 103 says that gl.clear is affected by the masks.