Simplify some selectionboxes significantly.

mods/nc_api/util_misc.lua

@@ -84,7 +84,12 @@ function nodecore.extend_item(name, func)
 	minetest.register_item(":" .. name, copy)
 end
 
-function nodecore.fixedbox(...) return {type = "fixed", fixed = {...}} end
+function nodecore.fixedbox(x, ...)
+	return {type = "fixed", fixed = {
+			x or {-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},
+			...
+		}}
+end
 
 function nodecore.interact(player)
 	if type(player) ~= "string" then

mods/nc_optics/lens.lua

@@ -43,6 +43,9 @@ local basedef = {
 		{0.25, -0.5, -3/8, 0.5, 0.25, 1/8},
 		{-0.25, -0.25, -1/8, 0.25, 0.25, 0.25}
 	),
+	selection_box = nodecore.fixedbox(
+		{-0.5, -0.5, -3/8, 0.5, 0.5, 1/8}
+	),
 	tiles = {
 		txr,
 		txr,

mods/nc_optics/prism.lua

@@ -31,6 +31,9 @@ local basedef = {
 		{-0.25, -0.25, 3/8, 0.25, 0.25, 0.5},
 		{-0.5, -0.25, -0.25, -3/8, 0.25, 0.25}
 	),
+	selection_box = nodecore.fixedbox(
+		{-3/8, -0.5, -0.5, 0.5, 0.5, 3/8}
+	),
 	tiles = {
 		txr,
 		txr,

mods/nc_tote/init.lua

@@ -99,9 +99,7 @@ minetest.register_node(modname .. ":handle", {
 			{3/8, 1/4, -0.5, 0.5, 3/8, 0.5},
 			{-0.5, 3/8, -1/8, 0.5, 0.5, 1/8}
 		),
-		selection_box = nodecore.fixedbox(
-			{-0.5, -0.5, -0.5, 0.5, 3/8, 0.5}
-		),
+		selection_box = nodecore.fixedbox(),
 		paramtype = "light",
 		tiles = {
 			"nc_lode_annealed.png",

mods/nc_woodwork/shelf.lua

@@ -20,12 +20,8 @@ minetest.register_node(modname .. ":shelf", {
 			{7/16, -7/16, -0.5, 0.5, 7/16, -7/16},
 			{7/16, -7/16, 7/16, 0.5, 7/16, 0.5}
 		),
-		selection_box = nodecore.fixedbox(
-			{-0.5, -0.5, -0.5, 0.5, 0.5, 0.5}
-		),
-		collision_box = nodecore.fixedbox(
-			{-0.5, -0.5, -0.5, 0.5, 0.5, 0.5}
-		),
+		selection_box = nodecore.fixedbox(),
+		collision_box = nodecore.fixedbox(),
 		tiles = { top, top, side },
 		groups = {
 			choppy = 1,