Shortcuts: Modulo | Colours | Time Triggers | Spatial Wrapping | Fakey Randomness

Modulo

Modulo wraps values, so (v % m) returns a value wrapped over the range 0 to m - 1.

There are a few circumstances where it’s a very solid tool for TIC, and extra useful for ByteJamming where the visuals are fed by generated values.

Colours

It’s very useful for keeping colours tamed:

local T=0
function TIC()
	cls()
	for i=0,80 do
		local c = 8 + i%4	-- blues
		circ(i*3, 30+i, 20, c)
	end
	T=T+1
end

Time Triggers

It’s great for making something happen periodically:

local T=0
function TIC()
	cls()
	for i=0,80 do
		local r=20
		if T%50<10 then
			r=40	-- blip the radius
		end
		circ(120, 68, r, 12)
	end
	T=T+1
end

We’ll have a look at using this to shuffle values in a later tip.

Spatial Wrapping

It’s neat for keeping things wrapping around the screen:

local T=0
function TIC()
	cls()	
	circ(T%280-20, 68, 20, 12)
	T=T+1
end

Fakey Randomness

There’s another cute pattern that allows you to make a bunch of values that look they’re generated randomly with a fixed seed, and without needing to worry about maintaining a list of objects. It takes the form:

( (i + shift) ^ spread ) % wrap

…where i is the index of your items, wrap represents one more than the largest value you’d like back, spread is whatever smallish number you can find that nicely scatters the values, and shift helps stops i == 0 returning 0.

In practise, this will look like:

function TIC()
	cls()	
	for i=0,100 do
		local x=((i+100)^5.3)%240
		local y=((i+100)^5.8)%136
		pix(x, y, 12)
	end
end

The spread terms may need some care because they can return very regular-looking patterns if the maths all lines up.