maybe i didnt read the code enough
i assumed that was targeting code for some reason, which it clearly isn't on further inspection. however, that whole block is still not fps independent...
rxe-rxm is confusing, personally I can't work out in my head if it breaks or not, but subtracting a time independant value from some constant (its constant this frame) doesn't seem like it should produce something time independent, it may change rxe time independently, but it is being altered then applied to make rxm change per frame:
rxm=rxm+(rxe-rxm)*k*dt would be much better
also you then go and add up and subtract down, which means you need to do this:
rxm=rxm+(rxe-rxm)*k*dt +up*dt + down*dt
basically when you have:
time_dependant = time_dependant + some_stuff
time_dependant = time_dependant + f(some_stuff, delta_t)
time_dependant = time_dependant + k*some_stuff*delta_t
btw, if you want to make your code more readable, don't use fps as the variable name in that context. fps means frames per second in a lot of contexts, what you are measuring is the number of seconds elapsed per frame, i.e. "seconds per frame" which is usually referred to simply as the change in time, or in more maths/science/computing contexts "delta t(ime)"
if you want the actual framerate in fps, do:
fps = 1/delta_t
EDIT: okay i worked out the rxe-rxm thing. It IS targeting, I just got confused trying to read and work it out:
rxm = .9*rxm+.1*rxe;
rxm -> rxe over time
the .9 and .1 need to change to match the time so that the targetting moves independently of framerate, e.g. for shorter frames you want to move less, for longer frames you want to move more. i think the correct way is like this:
optimiser = pow(.9,30*dt);
rxm = optimiser*rxm + (1-optimiser)*rxe;
this would give the same effect as using the current targetting at 30fps, except it adapts to the framerate changes.
On a side note, this trick is useful for making a sort-of time independent fadout effect, do a color modifier like this:
curve and speed control the speed and the 'brightness curve' used for the fadeout.
there are still differences at different framerates, but the overall brightness should remain roughly the same, eliminating the classic 'white preset' problems.