This commit adds a new rendering backend, GLES2, and adds a
project setting to enable it.
Currently this backend can only be used on the X11 platform,
but integrating into other platforms is planned.
Done with `autopep8 --select=E7`, fixes:
- E701 - Put colon-separated compound statement on separate lines.
- E702 - Put semicolon-separated compound statement on separate lines.
- E703 - Put semicolon-separated compound statement on separate lines.
- E711 - Fix comparison with None.
- E712 - Fix (trivial case of) comparison with boolean.
- E713 - Fix (trivial case of) non-membership check.
- E721 - Fix various deprecated code (via lib2to3).
The reordering of the SConscript includes allows to ensure that
stuff like the builtin zlib headers will be available for libpng.
Also moved glew back into global env, otherwise windows seems
not to find it... Kind of shooting in the dark with this multi-env
setup.
Added support for 2D shadow casters.
*DANGER* Shaders in CanvasItem CHANGED, if you are using shader in a
CanvasItem and pull this, you will lose them. Shaders now work through a
2D material system similar to 3D. If you don't want to lose the 2D
shader code, save the shader as a .shd, then create a material in
CanvasItem and re-assign the shader.
