rlm@158: #+title: Movement!
rlm@158: #+author: Robert McIntyre
rlm@158: #+email: rlm@mit.edu
rlm@158: #+description: muscles for a simulated creature
rlm@158: #+keywords: simulation, jMonkeyEngine3, clojure
rlm@158: #+SETUPFILE: ../../aurellem/org/setup.org
rlm@158: #+INCLUDE: ../../aurellem/org/level-0.org
rlm@158: 
rlm@180: 
rlm@180: Surprisingly enough, terristerial creatures only move by using torque
rlm@180: applied about their joints.  There's not a single straight line of
rlm@180: force in the human body at all!  (A straight line of force would
rlm@180: correspond to some sort of jet or rocket propulseion.)
rlm@180: 
rlm@180: 
rlm@180: Here's how motor-control/ proprioception will work: Each muscle is
rlm@180: defined by a 1-D array of numbers (the "motor pool") each of which
rlm@180: represent muscle fibers. A muscle also has a scalar :strength factor
rlm@180: which determines how strong the muscle as a whole is.  The effector
rlm@180: function for a muscle takes a number < (count motor-pool) and that
rlm@180: number is said to "activate" all the muscle fibers whose index is
rlm@180: lower than the number.  Each fiber will apply force in proportion to
rlm@180: its value in the array.  Lower values cause less force.  The lower
rlm@180: values can be put at the "beginning" of the 1-D array to simulate the
rlm@180: layout of actual human muscles, which are capable of more percise
rlm@180: movements when exerting less force.
rlm@180: 
rlm@158: #+name: movement
rlm@158: #+begin_src clojure 
rlm@158: (ns cortex.movement
rlm@180:   "Give simulated creatures defined in special blender files the power
rlm@180:    to move around in a simulated environment."
rlm@180:   {:author "Robert McIntyre"}
rlm@158:   (:use (cortex world util sense body))
rlm@180:   (:use clojure.contrib.def)
rlm@180:   (:import java.awt.image.BufferedImage)
rlm@180:   (:import com.jme3.scene.Node)
rlm@180:   (:import com.jme3.math.Vector3f)
rlm@180:   (:import com.jme3.bullet.control.RigidBodyControl))
rlm@158: 
rlm@180: (defn muscle-profile
rlm@180:   "Return a vector where each entry is the strength of the \"motor
rlm@180:   pool\" at that part in the muscle."
rlm@180:   [#^BufferedImage profile]
rlm@158:   (vec
rlm@180:    (let [width (.getWidth profile)]
rlm@158:      (for [x (range width)]
rlm@158:        (- 255
rlm@158:           (bit-and
rlm@158:            0x0000FF
rlm@180:            (.getRGB profile x 0)))))))
rlm@158: 
rlm@180: (defvar 
rlm@180:   ^{:arglists '([creature])}
rlm@180:   muscles
rlm@180:   (sense-nodes "muscles")
rlm@180:   "Return the children of the creature's \"muscles\" node.")
rlm@158: 
rlm@180: (defn movement-fn
rlm@180:   "Returns a function which when called with a integer value inside a
rlm@191:    running simulation will cause movement in the creature according
rlm@191:    to the muscle's position and strength profile. Each function
rlm@191:    returns the amount of force applied / max force."
rlm@180:   [#^Node parts #^Node muscle]
rlm@158:   (let [target (closest-node parts muscle)
rlm@158:         axis
rlm@158:         (.mult (.getWorldRotation muscle) Vector3f/UNIT_Y)
rlm@158:         strength (meta-data muscle "strength")
rlm@158:         image-name (read-string (meta-data muscle "muscle"))
rlm@180:         image (load-image image-name)
rlm@180:         fibers (muscle-profile image)
rlm@158:         fiber-integral (reductions + fibers)
rlm@191:         force-index
rlm@191:         (vec (map  #(float (* strength (/ % (last fiber-integral))))
rlm@191:               fiber-integral))
rlm@158:         control (.getControl target RigidBodyControl)]
rlm@158:     (fn [n]
rlm@191:       (let [pool-index (max 0 (min n (dec (count fibers))))
rlm@191:             force (force-index pool-index)]
rlm@191:         (.applyTorque control (.mult axis force))
rlm@191:         (float (/ force strength))))))
rlm@191:         
rlm@158: 
rlm@180: (defn movement!
rlm@180:   "Endow the creature with the power of movement. Returns a sequence
rlm@180:    of functions, each of which accept an integer value and will
rlm@180:    activate their corresponding muscle."
rlm@158:   [#^Node creature]
rlm@180:     (for [muscle (muscles creature)]
rlm@180:       (movement-fn creature muscle)))
rlm@158: 
rlm@191: (defn movement-display-kernel
rlm@191:   "Display muscle exertion data as a bar filling up with red."
rlm@191:   [exertion]
rlm@191:      (let [height 20
rlm@191:            width 300
rlm@191:            image (BufferedImage. width height
rlm@191:                                  BufferedImage/TYPE_INT_RGB)
rlm@191:            fill (min (int (* width exertion)) width)]
rlm@191:        (dorun
rlm@191:         (for [x (range fill)
rlm@191:               y (range height)]
rlm@191:           (.setRGB image x y 0xFF0000)))
rlm@191:        image))
rlm@191: 
rlm@191: (defn view-movement
rlm@191:   "Creates a function which accepts a list of muscle-exertion data and
rlm@191:   displays each element of the list to the screen."
rlm@191:   []
rlm@191:   (view-sense movement-display-kernel))
rlm@191: 
rlm@158: #+end_src
rlm@158: 
rlm@158: 
rlm@158: 
rlm@158: 
rlm@158: 
rlm@158: * COMMENT code generation
rlm@158: #+begin_src clojure :tangle ../src/cortex/movement.clj
rlm@158: <<movement>>
rlm@158: #+end_src