This is in preparation for using persistently mapped buffers for uniform
buffers. Since that functionality is not available in the OpenGL version
we are targetting I implemented a fall-back which simply uses
glBufferSubData.
I did a benchmark with these changes and there was no change in
performance to the current master version.
Since the system already tracks if a buffer is still in use by the GPU
the buffer updates can assume that there will be no synchronization
issues if the buffer is mapped into memory.
This converts the deferred lighting shader to use uniform buffers for
the dynamic data sent to the GPU while rendering the lighting effects.
This doesn't affect performance but the deferred lighting code is a
nicely isolated piece of rendering code where I could test how the
rendering code could use the uniform buffers.
This is related to #910.
asarium