This needs to be moved into the backend, and partially into the shader. So far this only removes the code from the main rendering logic, the final implementation is not done yet.
It had to go because it required the main rendering code to look deep into the texture data which would be a major blocker for refactoring.
These will have to do some texture management bookkeeping so directly changing the values is problematic.
This required changing the parameter interface in polymost.cpp because a few places hacked around with the global state to pass parameters to subfunctions.
