refactor as library

1 files changed, 45 insertions, 32 deletions

diff --git a/main.lua b/main.lua
index ff212f5..7b0a7c0 100644
--- a/main.lua
+++ b/main.lua
@@ -1,26 +1,5 @@
 local G = love.graphics
 
-local function plot(f,x0,xn)
-	local n = 30
-	x0 = x0 or G.inverseTransformPoint(0,0)
-	xn = xn or G.inverseTransformPoint(G.getDimensions(),0)
-
-	if xn < x0 then
-		xn,x0 = x0,xn
-	end
-
-	local h = (xn-x0)/n
-	local ps = {}
-	for i=0,n do
-		local x = x0 + i*h
-		local y = f(x)
-		table.insert(ps,x)
-		table.insert(ps,y)
-	end
-	G.line(ps)
-end
-
-
 local function atanh(x)
 	return (1/2) * math.log((1+x)/(1-x))
 end
@@ -38,12 +17,27 @@ local function solve_for_A(r)
 	return A
 end
 
-local L = 3
-function love.wheelmoved(x,y)
-	L = L + (y/5)
+local function plot(f,x0,xn)
+	local n = 30
+	x0 = x0 or G.inverseTransformPoint(0,0)
+	xn = xn or G.inverseTransformPoint(G.getDimensions(),0)
+
+	if xn < x0 then
+		xn,x0 = x0,xn
+	end
+
+	local h = (xn-x0)/n
+	local ps = {}
+	for i=0,n do
+		local x = x0 + i*h
+		local y = f(x)
+		table.insert(ps,x)
+		table.insert(ps,y)
+	end
+	return ps
 end
 
-local function catenary0(x1,y1,x2,y2)
+local function catenary0(x1,y1,x2,y2, L)
 	-- https://math.stackexchange.com/a/3557768
 	y1 = -y1
 	y2 = -y2
@@ -53,7 +47,7 @@ local function catenary0(x1,y1,x2,y2)
 	local my = (y1+y2)/2
 
 	local D = math.sqrt(dx^2+dy^2)
-	-- local L = D+(1/D)
+	L = L or D+(1/(D+0.3))
 
 	local r = math.sqrt(L^2 - dy^2)/dx
 	local A = solve_for_A(r)
@@ -64,14 +58,27 @@ local function catenary0(x1,y1,x2,y2)
 
 	return function(x) return -(a * math.cosh((x-b)/a) + c) end
 end
-local function catenary(x1,y1,x2,y2)
+
+
+local function catenary(x1,y1, x2,y2, L)
+	local D = math.sqrt((x2-x1)^2 + (y2-y1)^2)
+	L = L or D+(1/(D+0.3))
+
 	if x2 < x1 then
 		x1,x2 = x2,x1
 		y1,y2 = y2,y1
 	end
-	return catenary0(x1,y1,x2,y2)
+
+	local f = catenary0(x1,y1,x2,y2,L)
+	return plot(f, x1,x2)
 end
 
+return {
+	catenary = catenary
+}
+
+
+--[[
 local Ps = {{-1,1}, {1,1}}
 
 function love.update(dt)
@@ -88,10 +95,15 @@ function love.draw()
 	G.clear(1,1,1)
 	G.setColor(0,0,0)
 	G.origin()
-	G.print(L,10,10)
+	local dx = Ps[1][1] - Ps[2][1]
+	local dy = Ps[1][2] - Ps[2][2]
+	local D = math.sqrt(dx^2+dy^2)
+	local L = D+(1/(D+0.3))
+	-- local L = D+1
+	G.print(("%.2f\n%.2f\n%.2f"):format(L,D,L-D),10,10)
 	G.setLineWidth(0.01)
 	G.translate(W/2,H/2)
-	G.scale(150)
+	G.scale(50)
 
 	G.setColor(0.8,0.8,0.8)
 	for i=-10,10 do
@@ -108,11 +120,12 @@ function love.draw()
 	-- plot(atanh)
 
 	G.setColor(0,0,0)
-	plot(catenary(Ps[1][1],Ps[1][2], Ps[2][1], Ps[2][2]),
-		Ps[1][1], Ps[2][1])
+	G.line(catenary(Ps[1][1],Ps[1][2], Ps[2][1], Ps[2][2]))
 
 	G.setColor(1,0,0)
 	G.circle('fill',Ps[1][1],Ps[1][2],0.05)
 	G.setColor(0,0,1)
 	G.circle('fill',Ps[2][1],Ps[2][2],0.05)
 end
+--]]
+