main.lua

@@ -1,5 +1,5 @@
 function lerp(x0, x1, t)
-    return x0*(1-t) + x1*t
+	return x0*(1-t) + x1*t
 end
 
 function blendExp(x0, x1, t)
@@ -18,27 +18,27 @@ local coordsAL = {}
 local coordsBL = {}
 
 local input = {
-	0.9013,
-	1.3685,
-	1.1046,
-	1.1633,
-	0.7332,
-	0.8603,
+	  [0]=0.9013,
+	 [60]=1.3685,
+	[120]=1.1046,
+	[180]=1.1633,
+	[240]=0.7332,
+	[300]=0.8603,
+	[360]=0.9013,
 }
+local xPrecision = 60/20
 
 local win = {
 	T = 1.5,
 	B = -0.5,
 	L = 0,
-	R = 1,
-	stepX = 0.1,
+	R = 360,
+	stepX = 30,
 	stepY = 0.25,
 }
 win.scaleX = 1/(win.L - win.R)
 win.scaleY = 1/(win.T - win.B)
 
-local precision = 32
-
 function screenX(x)
 	return sw*(win.L-x)*win.scaleX
 end
@@ -52,11 +52,33 @@ function addPoint(coords, x, y)
 	coords[#coords+1] = screenY(y)
 end
 
-function interpolate(x, values, interpolator)
-	local x = (x*#values) % #values
-	local x0 = math.floor(x)
-	local x1 = (x0 + 1) % #values
-	return interpolator(values[x0+1], values[x1+1], x - x0)
+function index(t, x)
+	if type(x) ~= type(0) then
+		return nil
+	end
+
+	local x0
+	local x1
+	for tx, ty in pairs(t) do
+		-- we can't guarantee the order the key/values come in
+		if tx ~= "interpolator" then
+			-- x0 = largest tx that doesn't go over x
+			if tx <= x and (x0 == nil or tx > x0) then
+				x0 = tx
+			end
+			-- x1 = smallest tx that doesn't go under x
+			if tx > x and (x1 == nil or tx < x1) then
+				x1 = tx
+			end
+		end
+	end
+	x1 = x1 or x0
+
+	local y0 = rawget(t, x0)
+	local y1 = rawget(t, x1)
+	local f = rawget(t, "interpolator")
+	local y = f(y0, y1, (x - x0)/(x1 - x0))
+	return y
 end
 
 function love.load()
@@ -68,19 +90,18 @@ function love.load()
 
 	--font = love.graphics.newFont("DejaVuSansMono.ttf", fs)
 	--love.graphics.setFont(font)
+	setmetatable(input, {__index = index})
 
-	local lines = #input * precision
-	local seg = 1/lines
-
-	for n=1, lines+1 do
-		local x = (n-1)*seg
-		local hue = (n-1)/lines
-
-		local y = interpolate(hue, input, lerp)
+	input.interpolator = lerp
+	for x=win.L, win.R, xPrecision do
+		local y = input[x]
 		addPoint(coordsA, x, y)
 		addPoint(coordsAL, x, math.log(y))
+	end
 
-		y = interpolate(hue, input, blendExp)
+	input.interpolator = blendExp
+	for x=win.L, win.R, xPrecision do
+		local y = input[x]
 		addPoint(coordsB, x, y)
 		addPoint(coordsBL, x, math.log(y))
 	end