Depth buffers problems on Android devices with Adreno GPUs

[GoogleCodeExporter]

There is a known issue on Adreno GPU's, where if the last rendered object 
turned off depth writing, it would trash the depth buffer.

Solution:

call:
GLES20.glDepthMask(true);

before any glClear()'s of the depth buffer.

The only glClear happens in clearBuffers() of OGLESShaderRenderer.java. Putting 
it right before glClear() solves the issue.

Original issue reported on code.google.com by wezr...@hotmail.com on 20 Mar 2014 at 1:56