fix slab_z nodebox direction inconsistencies

homedecor/gastronomy.lua

@@ -80,7 +80,7 @@ homedecor.register("4_bottles_multi", {
 	selection_box = fbottle_cbox
 })
 
-local wine_cbox = homedecor.nodebox.slab_z(0.25)
+local wine_cbox = homedecor.nodebox.slab_z(-0.75)
 homedecor.register("wine_rack", {
 	description = "Wine Rack",
 	mesh = "homedecor_wine_rack.obj",

homedecor/handlers/nodeboxes.lua

@@ -4,8 +4,20 @@
 
 -- a box is defined as {x1, y1, z1, x2, y2, z2}
 homedecor.box = {
+	-- bottom slab (starting from -y) with height optionally shifted upwards
 	slab_y = function(height, shift) return { -0.5, -0.5+(shift or 0), -0.5, 0.5, -0.5+height+(shift or 0), 0.5 } end,
-	slab_z = function(depth) return { -0.5, -0.5, -0.5+depth, 0.5, 0.5, 0.5 } end,
+	slab_z = function(depth)
+		-- for consistency with the other functions here, we have to assume that a "z" slab starts from -z and extends by depth,
+		-- but since conventionally a lot of nodes place slabs against +z for player convenience, we define
+		-- a "negative" depth as a depth extending from the other side, i.e. +z
+		if depth > 0 then
+			-- slab starting from -z
+			return { -0.5, -0.5, -0.5, 0.5, 0.5, -0.5+depth }
+		else
+			-- slab starting from +z (z1=0.5-(-depth))
+			return { -0.5, -0.5, 0.5+depth, 0.5, 0.5, 0.5 }
+		end
+	end,
 	bar_y = function(radius) return {-radius, -0.5, -radius, radius, 0.5, radius} end,
 	cuboid = function(radius_x, radius_y, radius_z) return {-radius_x, -radius_y, -radius_z, radius_x, radius_y, radius_z} end,
 }

homedecor/misc-nodes.lua

@@ -249,7 +249,7 @@ homedecor.register("dvd_cd_cabinet", {
 		"homedecor_dvdcd_cabinet_front.png",
 		"homedecor_dvdcd_cabinet_back.png"
 	},
-	selection_box = homedecor.nodebox.slab_z(0.5),
+	selection_box = homedecor.nodebox.slab_z(-0.5),
 	groups = {choppy=2,oddly_breakable_by_hand=2},
 	sounds = default.node_sound_wood_defaults(),
 })