you see that wouldn't work that's what I said...
because this line
if (i < (NUM_LEDS/2)) {
in original code is like... leds 0-150 go slowly to brightest
and less 150-300 go slowly to darkest
so that middle point will always be at 150
so even if you move the index, that middle point doesn't change
in any way my animation doesn't move if I do that copy pasted