view org/world.org @ 41:cce471a4108a

done improving the touch article for tonight
author Robert McIntyre <rlm@mit.edu>
date Thu, 03 Nov 2011 10:42:28 -0700
parents 183744c179e6
children 00d0e1639d4b
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1 #+title: A Virtual World for Sensate Creatures
2 #+author: Robert McIntyre
3 #+email: rlm@mit.edu
4 #+description: Creating a Virtual World for AI constructs using clojure and JME3
5 #+keywords: JME3, clojure, virtual world, exception handling
6 #+SETUPFILE: ../../aurellem/org/setup.org
7 #+INCLUDE: ../../aurellem/org/level-0.org
8 #+BABEL: :mkdirp yes :noweb yes :exports both
10 * The World
12 There's no point in having senses if there's nothing to experience. In
13 this section I make some tools with which to build virtual worlds for
14 my characters to inhabit. If you look at the tutorials at [[http://www.jmonkeyengine.org/wiki/doku.php/jme3:beginner][the jme3
15 website]], you will see a pattern in how virtual worlds are normally
16 built. I call this "the Java way" of making worlds.
18 - The Java way:
19 - Create a class that extends =SimpleApplication= or =Application=
20 - Implement setup functions that create all the scene objects using
21 the inherited =assetManager= and call them by overriding the
22 =simpleInitApp= method.
23 - Create =ActionListeners= and add them to the =inputManager=
24 inherited from =Application= to handle key-bindings.
25 - Override =simpleUpdate= to implement game logic.
26 - Running/Testing an Application involves creating a new JVM,
27 running the App, and then closing everything down.
30 - A more Clojureish way:
31 - Use a map from keys->functions to specify key-bindings.
32 - Use functions to create objects separately from any particular
33 application.
34 - Use a REPL -- this means that there's only ever one JVM, and
35 Applications come and go.
37 Since most development work using jMonkeyEngine is done in Java, jme3
38 supports "the Java way" quite well out of the box. To work "the
39 clojure way", it necessary to wrap the JME3 elements that deal with
40 the Application life-cycle with a REPL driven interface.
42 The most important modifications are:
44 - Separation of Object life-cycles with the Application life-cycle.
45 - Functional interface to the underlying =Application= and
46 =SimpleApplication= classes.
48 ** Header
49 #+srcname: header
50 #+begin_src clojure :results silent
51 (ns cortex.world
52 "World Creation, abstracion over jme3's input system, and REPL
53 driven exception handling"
54 {:author "Robert McIntyre"}
56 (:use (clojure.contrib (def :only (defvar))))
57 (:use [pokemon [lpsolve :only [constant-map]]])
58 (:use [clojure.contrib [str-utils :only [re-gsub]]])
60 (:import com.aurellem.capture.IsoTimer)
62 (:import com.jme3.math.Vector3f)
63 (:import com.jme3.scene.Node)
64 (:import com.jme3.system.AppSettings)
65 (:import com.jme3.system.JmeSystem)
66 (:import com.jme3.input.KeyInput)
67 (:import com.jme3.input.controls.KeyTrigger)
68 (:import com.jme3.input.controls.MouseButtonTrigger)
69 (:import com.jme3.input.InputManager)
70 (:import com.jme3.bullet.BulletAppState)
71 (:import com.jme3.shadow.BasicShadowRenderer)
72 (:import com.jme3.app.SimpleApplication)
73 (:import com.jme3.input.controls.ActionListener)
74 (:import com.jme3.renderer.queue.RenderQueue$ShadowMode)
75 (:import org.lwjgl.input.Mouse))
76 #+end_src
78 ** General Settings
79 #+srcname: settings
80 #+begin_src clojure
81 (in-ns 'cortex.world)
83 (defvar *app-settings*
84 (doto (AppSettings. true)
85 (.setFullscreen false)
86 (.setTitle "Aurellem.")
87 ;; The "Send" AudioRenderer supports sumulated hearing.
88 (.setAudioRenderer "Send"))
89 "These settings control how the game is displayed on the screen for
90 debugging purposes. Use binding forms to change this if desired.
91 Full-screen mode does not work on some computers.")
93 (defn asset-manager
94 "returns a new, configured assetManager" []
95 (JmeSystem/newAssetManager
96 (.getResource
97 (.getContextClassLoader (Thread/currentThread))
98 "com/jme3/asset/Desktop.cfg")))
99 #+end_src
101 Normally, people just use the =AssetManager= inherited from
102 =Application= whenever they extend that class. However,
103 =AssetManagers= are useful on their own to create objects/ materials,
104 independent from any particular application. =(asset-manager)= makes
105 object creation less tightly bound to a particular Application
106 Instance.
109 ** Exception Protection
110 #+srcname: exceptions
111 #+begin_src clojure
112 (in-ns 'cortex.world)
114 (defmacro no-exceptions
115 "Sweet relief like I never knew."
116 [& forms]
117 `(try ~@forms (catch Exception e# (.printStackTrace e#))))
119 (defn thread-exception-removal
120 "Exceptions thrown in the graphics rendering thread generally cause
121 the entire REPL to crash! It is good to suppress them while trying
122 things out to shorten the debug loop."
123 []
124 (.setUncaughtExceptionHandler
125 (Thread/currentThread)
126 (proxy [Thread$UncaughtExceptionHandler] []
127 (uncaughtException
128 [thread thrown]
129 (println "uncaught-exception thrown in " thread)
130 (println (.getMessage thrown))))))
132 #+end_src
134 Exceptions thrown in the LWJGL render thread, if not caught, will
135 destroy the entire JVM process including the REPL and slow development
136 to a crawl. It is better to try to continue on in the face of
137 exceptions and keep the REPL alive as long as possible. Normally it
138 is possible to just exit the faulty Application, fix the bug,
139 reevaluate the appropriate forms, and be on your way, without
140 restarting the JVM.
142 ** Input
143 #+srcname: input
144 #+begin_src clojure
145 (in-ns 'cortex.world)
147 (defn all-keys
148 "Uses reflection to generate a map of string names to jme3 trigger
149 objects, which govern input from the keyboard and mouse"
150 []
151 (let [inputs (pokemon.lpsolve/constant-map KeyInput)]
152 (assoc
153 (zipmap (map (fn [field]
154 (.toLowerCase (re-gsub #"_" "-" field))) (vals inputs))
155 (map (fn [val] (KeyTrigger. val)) (keys inputs)))
156 ;;explicitly add mouse controls
157 "mouse-left" (MouseButtonTrigger. 0)
158 "mouse-middle" (MouseButtonTrigger. 2)
159 "mouse-right" (MouseButtonTrigger. 1))))
161 (defn initialize-inputs
162 "Establish key-bindings for a particular virtual world."
163 [game input-manager key-map]
164 (doall
165 (map (fn [[name trigger]]
166 (.addMapping
167 ^InputManager input-manager
168 name (into-array (class trigger)
169 [trigger]))) key-map))
170 (doall
171 (map (fn [name]
172 (.addListener
173 ^InputManager input-manager game
174 (into-array String [name]))) (keys key-map))))
176 #+end_src
178 These functions are for controlling the world through the keyboard and
179 mouse.
181 I reuse =constant-map= from [[../../pokemon-types/html/lpsolve.html#sec-3-2-4][=pokemon.lpsolve=]] to get the numerical
182 values for all the keys defined in the =KeyInput= class. The
183 documentation for =constant-map= is:
185 #+begin_src clojure :results output :exports both
186 (doc pokemon.lpsolve/constant-map)
187 #+end_src
189 #+results:
190 : -------------------------
191 : pokemon.lpsolve/constant-map
192 : ([class])
193 : Takes a class and creates a map of the static constant integer
194 : fields with their names. This helps with C wrappers where they have
195 : just defined a bunch of integer constants instead of enums
197 #+begin_src clojure :exports both :results verbatim
198 (take 5 (vals (pokemon.lpsolve/constant-map KeyInput)))
199 #+end_src
201 #+results:
202 : ("KEY_ESCAPE" "KEY_1" "KEY_2" "KEY_3" "KEY_4")
204 =(all-keys)= converts the constant names like =KEY_J= to the more
205 clojure-like =key-j=, and returns a map from these keys to
206 jMonkeyEngine =KeyTrigger= objects, which jMonkeyEngine3 uses as it's
207 abstraction over the physical keys. =all-keys= also adds the three
208 mouse button controls to the map.
210 #+begin_src clojure :exports both :results output
211 (require 'clojure.contrib.pprint)
212 (clojure.contrib.pprint/pprint
213 (take 6 (cortex.world/all-keys)))
214 #+end_src
216 #+results:
217 : (["key-n" #<KeyTrigger com.jme3.input.controls.KeyTrigger@9f9fec0>]
218 : ["key-apps" #<KeyTrigger com.jme3.input.controls.KeyTrigger@28edbe7f>]
219 : ["key-pgup" #<KeyTrigger com.jme3.input.controls.KeyTrigger@647fd33a>]
220 : ["key-f8" #<KeyTrigger com.jme3.input.controls.KeyTrigger@24f97188>]
221 : ["key-o" #<KeyTrigger com.jme3.input.controls.KeyTrigger@685c53ff>]
222 : ["key-at" #<KeyTrigger com.jme3.input.controls.KeyTrigger@4c3e2e5f>])
224 ** World Creation
225 #+srcname: world
226 #+begin_src clojure :results silent
227 (in-ns 'cortex.world)
229 (defn no-op
230 "Takes any number of arguments and does nothing."
231 [& _])
233 (defn traverse
234 "apply f to every non-node, deeply"
235 [f node]
236 (if (isa? (class node) Node)
237 (dorun (map (partial traverse f) (.getChildren node)))
238 (f node)))
240 (defn world
241 "the =world= function takes care of the details of initializing a
242 SimpleApplication.
244 ***** Arguments:
246 - root-node : a com.jme3.scene.Node object which contains all of
247 the objects that should be in the simulation.
249 - key-map : a map from strings describing keys to functions that
250 should be executed whenever that key is pressed.
251 the functions should take a SimpleApplication object and a
252 boolean value. The SimpleApplication is the current simulation
253 that is running, and the boolean is true if the key is being
254 pressed, and false if it is being released. As an example,
256 {\"key-j\" (fn [game value] (if value (println \"key j pressed\")))}
258 is a valid key-map which will cause the simulation to print a
259 message whenever the 'j' key on the keyboard is pressed.
261 - setup-fn : a function that takes a SimpleApplication object. It
262 is called once when initializing the simulation. Use it to
263 create things like lights, change the gravity, initialize debug
264 nodes, etc.
266 - update-fn : this function takes a SimpleApplication object and a
267 float and is called every frame of the simulation. The float
268 tells how many seconds is has been since the last frame was
269 rendered, according to whatever clock jme is currently
270 using. The default is to use IsoTimer which will result in this
271 value always being the same.
272 "
273 [root-node key-map setup-fn update-fn]
274 (let [physics-manager (BulletAppState.)]
275 (doto
276 (proxy [SimpleApplication ActionListener] []
277 (simpleInitApp
278 []
279 (no-exceptions
280 ;; allow AI entities as much time as they need to think.
281 (.setTimer this (IsoTimer. 60))
282 (.setFrustumFar (.getCamera this) 300)
283 ;; Create default key-map.
284 (initialize-inputs this (.getInputManager this) (all-keys))
285 ;; Don't take control of the mouse
286 (org.lwjgl.input.Mouse/setGrabbed false)
287 ;; add all objects to the world
288 (.attachChild (.getRootNode this) root-node)
289 ;; enable physics
290 ;; add a physics manager
291 (.attach (.getStateManager this) physics-manager)
292 (.setGravity (.getPhysicsSpace physics-manager)
293 (Vector3f. 0 -9.81 0))
294 ;; go through every object and add it to the physics
295 ;; manager if relevant.
296 (traverse (fn [geom]
297 (dorun
298 (for [n (range (.getNumControls geom))]
299 (do
300 (.add (.getPhysicsSpace physics-manager)
301 (.getControl geom n))))))
302 (.getRootNode this))
303 ;; call the supplied setup-fn
304 (if setup-fn
305 (setup-fn this))))
306 (simpleUpdate
307 [tpf]
308 (no-exceptions
309 (update-fn this tpf)))
310 (onAction
311 [binding value tpf]
312 ;; whenever a key is pressed, call the function returned
313 ;; from key-map.
314 (no-exceptions
315 (if-let [react (key-map binding)]
316 (react this value)))))
317 ;; don't show a menu to change options.
318 (.setShowSettings false)
319 ;; continue running simulation even if the window has lost
320 ;; focus.
321 (.setPauseOnLostFocus false)
322 (.setSettings *app-settings*))))
323 #+end_src
326 =(world)= is the most important function here. It presents a more
327 functional interface to the Application life-cycle, and all its
328 arguments except =root-node= are plain immutable clojure data
329 structures. This makes it easier to extend functionally by composing
330 multiple functions together, and to add more keyboard-driven actions
331 by combining clojure maps.
335 * COMMENT code generation
336 #+begin_src clojure :tangle ../src/cortex/world.clj :noweb yes
337 <<header>>
338 <<settings>>
339 <<exceptions>>
340 <<input>>
341 <<world>>
342 #+end_src