Almost working from 1st try

port.lua

@@ -0,0 +1,71 @@
+require 'gridpoint'
+
+---@enum Alignment
+Alignment = {
+    Vertical = true,
+    Horizontal = false
+}
+
+---@enum PortRotation
+PortRotation = {
+    right = {false, false},
+    down = {false, true},
+    left = {true, false},
+    up = {true, true}
+}
+
+---@class Port
+---@field position GridPoint
+---@field alignment Alignment
+---@field scanOffset number
+---@field color table
+Port = {
+    position = GridPoint:new(0, 0),
+    alignment = Alignment.Vertical,
+    scanOffset = 0,
+    color = { 0.8, 0.8, 0, 1 }
+}
+
+---@param position GridPoint
+---@param rotation PortRotation
+---@param color table
+---@return Port
+function Port:new(position, rotation, color)
+    local port = {
+        position = position or self.position,
+        alignment = self.alignment,
+        scanOffset = self.scanOffset,
+        color = color or self.color
+    }
+    if rotation ~= nil then
+        port.scanOffset = rotation[1] and 1 or 0
+        port.alignment = rotation[2]
+    end
+
+    setmetatable(port, { __index = self })
+
+    return port
+end
+
+function Port:rotateClockwise()
+    local swap = self.position.x
+    self.position.x = -self.position.y
+    self.position.y = swap
+    self.scanOffset = (self.scanOffset == 1) == self.alignment and 1 or 0
+    self.alignment = not self.alignment
+end
+
+---@param offset GridPoint
+function Port:draw( offset )
+    love.graphics.setColor(self.color)
+    local drawPoint = GridPoint:new(
+        offset.x + self.position.x + self.scanOffset,
+        offset.y + self.position.y + self.scanOffset
+    )
+    local x, y = drawPoint:globalCoords()
+    x = self.alignment and x - Config.cellSize / 2 or x - Config.portWidth / 2 - Config.cellSize / 2
+    y = self.alignment and y - Config.portWidth / 2 - Config.cellSize / 2 or y - Config.cellSize / 2
+    local w = self.alignment and Config.cellSize or Config.portWidth
+    local h = self.alignment and Config.portWidth or Config.cellSize
+    love.graphics.rectangle("fill", x, y, w, h)
+end