Add directional sticky and skewer box variants

box_variants.lua

@@ -0,0 +1,36 @@
+local BoxVariants = {}
+
+-- Add directional sticky-puller and all-edge skewer variants for every authored
+-- moveable box. Both share sprite paths and collision cells with their base.
+function BoxVariants.addTo(assets)
+	local baseBoxes = {}
+	for name, properties in pairs(assets) do
+		if properties.class == "moveable" and name:match("^box") then
+			table.insert(baseBoxes, {name = name, properties = properties})
+		end
+	end
+
+	local function addVariant(base, prefix, behavior, directory, visualFlag)
+		local name = prefix .. base.name
+		local properties = {
+			class = behavior,
+			directory = directory,
+			sprites = base.properties.sprites,
+			cells = base.properties.cells,
+			preload = base.properties.preload,
+			synthetic = true,
+			baseAsset = base.name,
+		}
+		properties[visualFlag] = true
+		assets[name] = properties
+	end
+
+	for _, base in ipairs(baseBoxes) do
+		addVariant(base, "sticky_", "sticky", "sticky", "goopy")
+		addVariant(base, "skewer_", "skewer", "skewer", "skewer")
+	end
+
+	return assets
+end
+
+return BoxVariants