Almost working from 1st try

main.lua

@@ -0,0 +1,33 @@
+require 'point'
+require 'gridpoint'
+require 'mouse'
+require 'mechanism'
+require 'port'
+
+function love.load()
+    Screenw, Screenh = love.window.getMode()
+    Gridw, Gridh = Screenw / Config.cellSize, Screenh / Config.cellSize
+    local port = Port:new( GridPoint:new(-1, 0), PortRotation.left, { 0.8, 0.8, 0, 1 } )
+    Mecha1 = Mechanism:new( GridPoint:new(5, 5), GridPoint:new(3, 3), { port }, {0.5, 0.5, 0.5, 1} )
+end
+
+function love.update( dt )
+    dt = dt
+    Mouse:update()
+end
+
+function love.draw()
+    for i = 1, Gridw do
+        love.graphics.line( i * Config.cellSize, 0, i * Config.cellSize, Screenh )
+    end
+    for j = 1, Gridh do
+        love.graphics.line( 0, j * Config.cellSize, Screenw, j * Config.cellSize )
+    end
+    local mx, my = Mouse.point:globalCoords()
+    mx = mx - Config.cellSize / 2
+    my = my - Config.cellSize / 2
+    local mh, mw = Config.cellSize, Config.cellSize
+    love.graphics.rectangle("fill", mx, my, mh, mw)
+
+    Mecha1:draw()
+end