BGE bug-fix[#34523] 2dfilter produces render error (objects disappear) - likely an alpha problem
Fix for 2.66a

With help from Daniel Stokes and Mitchell Stokes.

This bug always existed in OSX, but started showing up in Windows and Linux on review (54745 + 54747)
[the patch to enable alpha buffer for all OSs]

A better fix would be to use RAS_IRasterizer::SetAlphaBlend(GPU_BLEND_SOLID);
but I think gpu_verify_alpha_blend() is not switching to SOLID because
GTS.alphablend is GPU_BLEND_SOLID (even though GL_ALPHA_TEST is enabled).

Anyways, this is not something worth tackling now, since in terms of functionality it shouldn't matter.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55010 954f8c5b-7b00-dc11-b283-0030488c597c