gists/main.lua

function lerp(x0, x1, t)
    return x0*(1-t) + x1*t
end

function blendExp(x0, x1, t)
	return x0^(1-t)*x1^t
end

local sw = 640
local sh = 480

local font
local fs = 12

local coordsA = {}
local coordsB = {}
local coordsAL = {}
local coordsBL = {}

local input = {
	0.9013,
	1.3685,
	1.1046,
	1.1633,
	0.7332,
	0.8603,
}

local win = {
	T = 1.5,
	B = -0.5,
	L = 0,
	R = 1,
	stepX = 0.1,
	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

function screenY(y)
	return sh*(win.T-y)*win.scaleY
end

function addPoint(coords, x, y)
	coords[#coords+1] = screenX(x)
	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)
end

function love.load()
	if not love.graphics.setMode(sw, sh) then
		error("couldn't setMode ("..sw.." by "..sh..")")
	end

	love.graphics.setCaption("hey it's a graph")

	--font = love.graphics.newFont("DejaVuSansMono.ttf", fs)
	--love.graphics.setFont(font)

	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)
		addPoint(coordsA, x, y)
		addPoint(coordsAL, x, math.log(y))

		y = interpolate(hue, input, blendExp)
		addPoint(coordsB, x, y)
		addPoint(coordsBL, x, math.log(y))
	end
end

function love.keypressed(key)
	if key == "escape" then
		love.event.push("quit")
	end
end

local drawCoords = love.graphics.line
local drawText = love.graphics.print

function color(hex)
	local r = tonumber(string.sub(hex, 1,2), 16)
	local g = tonumber(string.sub(hex, 3,4), 16)
	local b = tonumber(string.sub(hex, 5,6), 16)
	love.graphics.setColor(r,g,b)
end

function drawVert(x)
	drawCoords(x, 0, x, sh)
end

function drawHoriz(y)
	drawCoords(0, y, sw, y)
end

function love.draw()
	love.graphics.setBackgroundColor(255,255,255)
	love.graphics.clear()

	for x=win.L, win.R, win.stepX do
		color("d3e2e7")
		local rx = screenX(x)
		drawVert(rx)
		color("808080")
		drawText(tostring(x), rx, sh - fs)
	end

	for y=win.B, win.T, win.stepY do
		color("c6cce3")
		local ry = screenY(y)
		drawHoriz(ry)
		color("808080")
		drawText(tostring(y), 0, ry)
	end

	color("404040")
	drawVert(screenX(0))
	drawHoriz(screenY(0))

	color("57C1BB")
	drawCoords(coordsA)
	drawCoords(coordsAL)

	color("9F65C5")
	drawCoords(coordsB)
	drawCoords(coordsBL)
end