add a tonemapping (postprocessing) interface.

The floating point buffers really could use some tonemapping to allow it to
function as a HDR buffer.

We should think of an interface for the tonemapping.

Bare minimum:
- set gain
- set gamma (not really tonemapping, but we included it here anyway ;)
- select tone mapping method

Things that should be included too:
- bloom

Things I'm not sure of:
- set maximum white (this might conflict with gain for some methods, but
may be crucial for others)
- auto gain, so that log average luminance maps to middle grey
- auto max white, so that maximum luminance maps to 1

Things that would be very cool:
- allow user to provide custom pixel shader for tone mapping.  Possibly we
can use Nicolas Capens' softwire thing to use software pixel shaders if
hardware doesn't support it.

Glenn, what's your opinion?

Bram

Original issue reported on code.google.com by bram.deg...@gmail.com on 3 Aug 2007 at 8:43

Giladx / pixeltoaster

add a tonemapping (postprocessing) interface. #66