tweaks

1 files changed, 20 insertions, 6 deletions

diff --git a/main.lua b/main.lua
index 0f224d2..ecac412 100644
--- a/main.lua
+++ b/main.lua
@@ -5,6 +5,10 @@ local function plot(f,x0,xn)
 	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
@@ -39,7 +43,7 @@ function love.wheelmoved(x,y)
 	L = L + (y/5)
 end
 
-local function catenary(x1,y1,x2,y2)
+local function catenary0(x1,y1,x2,y2)
 	y1 = -y1
 	y2 = -y2
 	local dx = x2-x1
@@ -48,7 +52,7 @@ local function catenary(x1,y1,x2,y2)
 	local my = (y1+y2)/2
 
 	local D = math.sqrt(dx^2+dy^2)
-	-- local L = D*1.2
+	-- local L = D+(1/D)
 
 	local r = math.sqrt(L^2 - dy^2)/dx
 	local A = solve_for_A(r)
@@ -59,6 +63,13 @@ local function catenary(x1,y1,x2,y2)
 
 	return function(x) return -(a * math.cosh((x-b)/a) + c) end
 end
+local function catenary(x1,y1,x2,y2)
+	if x2 < x1 then
+		x1,x2 = x2,x1
+		y1,y2 = y2,y1
+	end
+	return catenary0(x1,y1,x2,y2)
+end
 
 local Ps = {{-1,1}, {1,1}}
 
@@ -81,11 +92,13 @@ function love.draw()
 	G.translate(W/2,H/2)
 	G.scale(150)
 
-	-- G.setColor(0.8,0.8,0.8)
-	-- G.line(-10,0,10,0)
-	-- G.line(0,-10,0,10)
+	G.setColor(0.8,0.8,0.8)
+	for i=-10,10 do
+		G.line(-10,i,10,i)
+		G.line(i,-10,i,10)
+	end
 
-	-- G.circle('line',0,0,1)
+	G.circle('line',0,0,1)
 
 	-- G.setColor(0,0,0)
 	-- -- plot(function(x) return x^2 end)
@@ -93,6 +106,7 @@ function love.draw()
 	-- G.setColor(0,1,0)
 	-- 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])