Some work to make hotkeys a 'real thing' on the lua side

luprex/lua/control.lst

@@ -5,4 +5,5 @@
 
 ut-table.lua
 ut-tablecmp.lua
+hotkeys.lua
 login.lua

luprex/lua/hotkeys.lua

@@ -0,0 +1,82 @@
+----------------------------------------------------------------
+--
+-- To add hotkeys to an object (such as a Brick Oven), you will
+-- be adding a function 'lookhotkeys' to the appropriate class,
+-- like this:
+--
+-- function brickoven.lookhotkeys(keys)
+--    keys:add("X", "Light Oven", function () ... end)
+--    keys:add("A", "Add Fuel", function () ... end)
+-- end
+--
+-- This function will get called twice: once in a 'probe' when
+-- Unreal wants to know what hotkeys exist, and a second time in
+-- an 'invoke' to find the right closure.
+--
+-- When the probe happens, we construct a "hotkeylist" to hold
+-- the complete list of hotkeys.  We populate this hotkeylist as
+-- follows:
+--
+--    local keys = hotkeylist.create()
+--    brickoven.lookhotkeys(keys)
+-- 
+-- At this point, if you were to pprint(keys), the output would
+-- look like this:
+--
+--    { "hotkeys", "X", "Light Oven", "A", "Add Fuel" }
+--
+-- The first array element is always the word "hotkeys".  Notice
+-- also that a hotkeylist doesn't store the closures, they are
+-- silently ignored.  The resulting array is in a format that can
+-- be returned directly to Unreal.
+--
+-- Later, when the user presses a key, such as the "Light Oven" key,
+-- we will construct a "hotkeypress" object whose job is to record
+-- the name of the hotkey that was pressed, and the closure that
+-- goes with it.  We populate this object as follows:
+--
+--    local keys = hotkeypress.create("Light Oven")
+--    brickoven.lookhotkeys(keys)
+--
+-- So as you can see, we're using the same 'brickoven.lookhotkeys'
+-- function, but this time, we've passed in a parameter of class
+-- hotkeypress instead of a parameter of class hotkeylist.  This
+-- changes the behavior of the 'add' method: the add function of
+-- a hotkeylist stores all the hotkeys into the list.  But the 'add'
+-- function of a hotkeypress only stores the one closure that
+-- we are interested in.  If you were to pprint(keys), the result
+-- would look like this:
+--
+--    { pressed="Light Oven", closure=<function> }
+--
+-- So the only data stored by a 'hotkeypress' object is the name
+-- of the pressed hotkey, and the closure that goes with it.
+--
+----------------------------------------------------------------
+
+makeclass("hotkeylist")
+makeclass("hotkeypress")
+
+function hotkeylist.create()
+    local result = { "hotkeys" }
+    setmetatable(result, hotkeylist)
+    return result
+end
+
+function hotkeylist.add(self, key, action, closure)
+    table.insert(self, key)
+    table.insert(self, action)
+end
+
+function hotkeypress.create(key)
+    local result = { pressed=key }
+    setmetatable(result, hotkeypress)
+    return result
+end
+
+function hotkeypress.add(self, key, action, closure)
+    if action == self.pressed then
+        self.closure = closure
+    end
+end
+

luprex/lua/login.lua

@@ -18,22 +18,34 @@ function engio.move(action, xyz, facing)
     tangible.animate(actor, nil, {action=action, xyz=xyz, facing=facing})
 end
 
-function cube.getlookat()
-    return { "Hotkeys", "X", "I Am a Cube" }
+function cube.lookhotkeys(keys)
+    keys:add("X", "Cube Hi", function () dprint("Cube Hi") end)
+    keys:add("A", "Cube Bye", function () dprint("Cube Bye") end)
 end
 
-function sphere.getlookat()
-    return { "Hotkeys", "X", "I Am a Sphere" }
+function sphere.lookhotkeys(keys)
+    keys:add("X", "Sphere Hi", function () dprint("Sphere Hi") end)
+    keys:add("A", "Sphere Bye", function () dprint("Sphere Bye") end)
 end
 
+
 function engio.getlookat()
     local class = tangible.getclass(tangible.place())
-    if class ~= nil then
-        local getlookat = class.getlookat
-        if getlookat ~= nil then
-            return getlookat()
-        end
+    if class == nil then return end
+
+    -- if the class has a function 'lookhotkeys', then the correct
+    -- look-at widget is 'hotkeys'.  We're going to automatically 
+    -- generate the correct response.
+    if class.lookhotkeys ~= nil then
+        local keys = hotkeylist.create()
+        class.lookhotkeys(keys)
+        setmetatable(keys, nil)
+        return keys
+    end
+
+    -- otherwise, if the class has a function 'getlookat', use that.
+    if class.getlookat ~= nil then
+        return class.getlookat()
     end
-    return ""
 end