-most of the time, unless you use a power of 2. :-P
-
-This has been solved below:
-UGB: pmo=(2.000000,687.000000) X=2, X%48=2, new x=45
-UGB: pmo=(1.000000,687.000000) X=1, X%48=1, new x=46
-UGB: pmo=(0.000000,687.000000) X=0, X%48=0, new x=47
-UGB: pmo=(-1.000000,687.000000) X=-1, X%48=15, new x=1
-UGB: pmo=(-2.000000,686.000000) X=-2, X%48=14, new x=2
-UGB: pmo=(-3.000000,686.000000) X=-3, X%48=13, new x=3
-
-Problem with changing grid size causes x/y origin to be shown incorrectly:
-UGB: pmo=(10.000000,812.000000) X=10, X%12=10, new x=2
-UGB: pmo=(10.000000,812.000000) X=10, X%4=2, new x=2
-UGB: pmo=(3.333333,818.666667) X=3, X%48=3, new x=45
-UGB: pmo=(39.000000,782.000000) X=39, X%48=39, new x=9 <-- MMB move is here
-UGB: pmo=(39.000000,781.000000) X=39, X%48=39, new x=9
-
-
-
+most of the time, unless you use a power of 2. :-P So what we do here is just
+take the modulus of the negation, which means we don't have to worry about
+mirroring it later.
+
+The positive case looks gruesome (and it is) but it boils down to this: We take
+the modulus of the X coordinate, then mirror it by subtraction from the
+maximum (in this case, gridPixels). This gives us a number in the range of 1 to
+gridPixels. But we need the case where the result equalling gridPixels to be
+zero; so we do another modulus operation on the result to achieve this.