Posted by Demoscene Passivist on Nov 14, 2010; 9:09am
URL: https://forum.jogamp.org/using-framebuffer-Depth-component-as-RGB-texture-tp1890224p1898244.html

U may have a look at my blog for a JOGL2 fixedfunction shadowmapping routine: http://copypastaresearch.tumblr.com/post/1454280770/ported-another-of-my-old-routines-to-jogl2-this

It copies the depthbuffer from the framebuffer to a texture and also includes a visualization for the depthbuffer when u set the mShowShadowMap boolean to true. It does not use OpenGL ES but I guess u should be able to easiely modify it for ES.