Implement basic HUD functionality

hud.lua

@@ -0,0 +1,55 @@
+local ipairs
+    = ipairs
+
+local minetest, vector
+    = minetest, vector
+
+local player_huds = {}
+
+local function do_player_rotating_checks(player)
+    local name = player:get_player_name()
+
+    local hud_index = player_huds[name]
+    if hud_index then
+        player:hud_remove(hud_index)
+        player_huds[name] = nil
+    end
+
+    local look_dir   = player:get_look_dir()
+    local player_pos = vector.copy(player:get_pos())
+    local eye_offset = vector.divide(player:get_eye_offset(), 10)
+    local eye_height = player:get_properties().eye_height;
+    local eye_pos    = player_pos + eye_offset + vector.new(0, eye_height, 0)
+
+    local default_reach = minetest.registered_items[""].range or 4
+    local wielded_reach = player:get_wielded_item():get_definition().reach
+    local reach = wielded_reach or default_reach
+
+    local node = nil
+    local ray = minetest.raycast(eye_pos, eye_pos + look_dir * reach, false, false)
+    for pointed_thing in ray do node = pointed_thing end
+
+    if node then
+        hud_index = player:hud_add({
+            hud_elem_type = "image",
+            name = "rotation hint",
+            text = "nc_extended_rotating_hud_rotate_clockwise.png",
+            position  = { x = 0.5, y = 0.5 },
+            offset    = { x = 0, y = 0 },
+            alignment = { x = 0, y = 0 },
+            scale     = { x = 1, y = 1 },
+        })
+        player_huds[name] = hud_index
+    end
+end
+
+minetest.register_globalstep(function(delta_time)
+    for _, player in ipairs(minetest.get_connected_players()) do
+        do_player_rotating_checks(player)
+    end
+end)
+
+minetest.register_on_leaveplayer(function(player)
+    local name = player:get_player_name()
+    player_huds[name] = nil
+end)

init.lua

@@ -2,6 +2,7 @@ local minetest, vector, include
     = minetest, vector, include
 
 local rotate = include("rotate")
+local hud    = include("hud")
 
 minetest.register_on_punchnode(function(pos, node, puncher, pointed_thing)
     local def = minetest.registered_nodes[node.name]