First round of dead file removal

experimental/flocking_geese/js/goose.js

-// Copyright (c) 2011 The Native Client Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-/**
- * @file
- * The Goose object.  This implements a single goose that flocks with other
- * geese in the flocking simulation.  Taken almost directly from
- * http://processingjs.org/learning/topic/flocking with references to
- * http://harry.me/2011/02/17/neat-algorithms---flocking.
- */
-
-
-goog.provide('Goose');
-
-goog.require('goog.Disposable');
-goog.require('goog.math.Vec2');
-
-/**
- * A Goose.  Starts the goose with a location and a velocity.
- * @param {?goog.math.Vec2} opt_location The initial location of this
- *     goose.  If not given, then the goose is started at (0, 0).
- * @param {?goog.math.Vec2} opt_velocity The initial velocity of this goose.
- *     If not given, then the goose is assigned a random velocity.
- * @constructor
- * @extends {goog.Disposable}
- */
-Goose = function(opt_location, opt_velocity) {
-  goog.Disposable.call(this);
-  /**
-   * The goose's current location.
-   * @type {goog.math.Vec2}
-   * @private
-   */
-  if (opt_location) {
-    this.location_ = opt_location.clone();
-  } else {
-    this.location_ = new goog.math.Vec2(0, 0);
-  }
-
-  /**
-   * The goose's current velocity.
-   * @type {goog.math.Vec2}
-   * @private
-   */
-  if (opt_velocity) {
-    this.velocity_ = opt_velocity.clone();
-  } else {
-    this.velocity_ = new goog.math.Vec2.randomUnit();
-  }
-};
-goog.inherits(Goose, goog.Disposable);
-
-/**
- * The maximum speed of a goose.  Measured in meters/second.
- * @type {number}
- */
-Goose.prototype.MAX_SPEED = 2.0;
-
-/**
- * The maximum force that can be applied to turn a goose when computing the
- * aligment.  Measured in meters/second/second.
- * @type {number}
- */
-Goose.prototype.MAX_TURNING_FORCE = 0.05;
-
-/**
- * The neighbour radius of a goose.  Only geese within this radius will affect
- * the flocking computations of this goose.  Measured in pixels.
- * @type {number}
- */
-Goose.prototype.NEIGHBOUR_RADIUS = 64.0;
-
-/**
- * The minimum distance that a goose can be from this goose.  If another goose
- * comes within this distance of this goose, the flocking algorithm tries to
- * move the geese apart.  Measured in pixels.
- * @type {number}
- */
-Goose.prototype.PERSONAL_SPACE = 32.0;
-
-/**
- * The distance at which attractors have effect on a goose's direction.
- * @type {number}
- */
-Goose.prototype.ATTRACTOR_RADIUS = 320.0;
-
-/**
- * The goose will try to turn towards geese within this distance (computed
- * during the cohesion phase).  Measured in pixels.
- * @type {number}
- */
-Goose.prototype.MAX_TURNING_DISTANCE = 100.0;
-
-/**
- * The weights used when computing the weighted sum the three flocking
- * components.
- * @type {number}
- */
-Goose.prototype.SEPARATION_WEIGHT = 2.0;
-Goose.prototype.ALIGNMENT_WEIGHT = 1.0;
-Goose.prototype.COHESION_WEIGHT = 1.0;
-
-/**
- * Override of disposeInternal() to dispose of retained objects and unhook all
- * events.
- * @override
- */
-Goose.prototype.disposeInternal = function() {
-  this.domElement_ = null;
-  Speedometer.superClass_.disposeInternal.call(this);
-}
-
-/**
- * Accessor for location.
- * @return {goog.math.Vec2} The current location.
- */
-Goose.prototype.location = function() {
-  return this.location_;
-}
-
-/**
- * Accessor for velocity.
- * @return {goog.math.Vec2} The current velocity.
- */
-Goose.prototype.velocity = function() {
-  return this.velocity_;
-}
-
-/**
- * Run one tick of the simulation.  Compute a new acceleration based on the
- * flocking algorithm (see Goose.flock()) and update the goose's location
- * by integrating acceleration and velocity.
- * @param {!Array.<Goose>} geese The list of all the geese in the flock.
- * @param {!Array.<goog.math.Vec2>} attractors The list of attractors.
- *     Geese have affinity for these points.
- * @param {?goog.math.Rect} opt_flockBox The geese will stay inside of this
- *     box.  If the parameter is not given, the geese don't have boundaries.
- */
-Goose.prototype.simulationTick = function(geese, attractors, opt_flockBox) {
-  var acceleration = this.flock(geese, attractors);
-  this.velocity_.add(acceleration);
-  // Limit the velocity to a maximum speed.
-  this.velocity_.clamp(this.MAX_SPEED);
-  this.location_.add(this.velocity_);
-  // Wrap the goose location to the flock box.
-  if (opt_flockBox) {
-    if (this.location_.x < opt_flockBox.left) {
-      this.location_.x = opt_flockBox.left + opt_flockBox.width;
-    }
-    if (this.location_.x > (opt_flockBox.left + opt_flockBox.width)) {
-      this.location_.x = opt_flockBox.left;
-    }
-    if (this.location_.y < opt_flockBox.top) {
-      this.location_.y = opt_flockBox.top + opt_flockBox.height;
-    }
-    if (this.location_.y > (opt_flockBox.top + opt_flockBox.height)) {
-      this.location_.y = opt_flockBox.top;
-    }
-  }
-}
-
-/**
- * Implement the flocking algorithm in five steps:
- *   1. Compute the separation component,
- *   2. Compute the alignment component,
- *   3. Compute the flock cohesion component.
- *   4. Compute the effect of the attractors and blend this in with the
- *      cohesion component.
- *   5. Create a weighted sum of the three components and use this as the
- *      new acceleration for the goose.
- * This is an O(n^2) version of the algorithm.  There are ways to speed this
- * up using spatial coherence techniques, but this version is much simpler.
- * @param {!Array.<Goose>} geese The list of all the neighbouring geese (in
- *     this implementation, this is all the geese in the flock).
- * @param {!Array.<goog.math.Vec2>} attractors The list of attractors.
- *     Geese have affinity for these points.
- * @return {goog.math.Vec2} The acceleration vector for this goose based on the
- *     flocking algorithm.
- */
-Goose.prototype.flock = function(geese, attractors) {
-  // Loop over all the neighbouring geese in the flock, accumulating
-  // the separation mean, the alignment mean and the cohesion mean.
-  var separationCount = 0;
-  var separation = new goog.math.Vec2(0, 0);
-  var alignCount = 0;
-  var alignment = new goog.math.Vec2(0, 0);
-  var cohesionCount = 0;
-  var cohesion = new goog.math.Vec2(0, 0);
-  for (var i = 0; i < geese.length; i++) {
-    var goose = geese[i];
-    // Compute the distance from this goose to its neighbour.
-    var gooseDirection = goog.math.Vec2.difference(
-        this.location_, goose.location());
-    var distance = gooseDirection.magnitude();
-    separationCount = this.accumulateSeparation_(
-        distance, gooseDirection, separation, separationCount);
-    alignCount = this.accumulateAlignment_(
-        distance, goose, alignment, alignCount);
-    cohesionCount = this.accumulateCohesion_(
-        distance, goose, cohesion, cohesionCount);
-  }
-  // Compute the means and create a weighted sum.  This becomes the goose's new
-  // acceleration.
-  if (separationCount > 0) {
-    separation.scale(1.0 / separationCount);
-  }
-  if (alignCount > 0) {
-    alignment.scale(1.0 / alignCount);
-    // Limit the effect that alignment has on the final acceleration.  The
-    // alignment component can overpower the others if there is a big
-    // difference between this goose's velocity and its neighbours'.
-    alignment.clamp(this.MAX_TURNING_FORCE);
-  }
-
-  // Compute the effect of the attractors and blend this in with the flock
-  // cohesion component.  An attractor has to be within ATTRACTOR_RADIUS to
-  // effect the heading of a goose.
-  for (var i = 0; i < attractors.length; i++) {
-    var attractorDirection = goog.math.Vec2.difference(
-        attractors[i], this.location_);
-    var distance = attractorDirection.magnitude();
-    if (distance < this.ATTRACTOR_RADIUS) {
-      attractorDirection.scale(1000);  // Each attractor acts like 1000 geese.
-      cohesion.add(attractorDirection);
-      cohesionCount += 1;
-    }
-  }
-
-  // If there is a non-0 cohesion component, steer the goose so that it tries
-  // to follow the flock.
-  if (cohesionCount > 0) {
-    cohesion.scale(1.0 / cohesionCount);
-    cohesion = this.turnTowardsTarget(cohesion);
-  }
-
-  // Compute the weighted sum.
-  separation.scale(this.SEPARATION_WEIGHT);
-  alignment.scale(this.ALIGNMENT_WEIGHT);
-  cohesion.scale(this.COHESION_WEIGHT);
-  var weightedSum = cohesion.clone();
-  weightedSum.add(alignment);
-  weightedSum.add(separation);
-  return weightedSum;
-}
-
-/**
- * Add a neighbouring goose's contribution to the separation mean.  Only
- * consider geese that have moved inside of this goose's personal space.
- * Modifies the separation accumulator |separation| in-place.
- * @param {!number} distance The distance from this goose to the neighbouring
- *     goose.
- * @param {!goog.math.Vec2} gooseDirection The direction vector from this
- *     goose to the neighbour.
- * @param {!goog.math.Vec2} separation The accumulated separation from all the
- *     neighbouring geese.
- * @param {!number} separationCount The current number of geese that have
- *     contributed to the separation component so far.
- * @return {!number} The new count of geese that contribute to the separation
- *     component.  If the goose under consideration does not contribute, this
- *     value is the same as |separationCount|.
- * @private
- */
-Goose.prototype.accumulateSeparation_ = function(distance,
-                                                 gooseDirection,
-                                                 separation,
-                                                 separationCount) {
-  if (distance > 0 && distance < this.PERSONAL_SPACE) {
-    var weightedDirection = gooseDirection;
-    weightedDirection.normalize();
-    weightedDirection.scale(1.0  / distance);
-    separation.add(weightedDirection);
-    separationCount++;
-  }
-  return separationCount;
-}
-
-/**
- * Add a neighbouring goose's contribution to the alignment mean.  Alignment is
- * the average velocity of the neighbours. Only consider geese that are within
- * |NEIGHBOUR_RADIUS|.  Modifies the alignment accumulator |alignment| in-place.
- * @param {!number} distance The distance from this goose to the neighbouring
- *     goose.
- * @param {!Goose} goose The neighbouring goose under consideration.
- * @param {!goog.math.Vec2} alignment The accumulated alignment from all the
- *     neighbouring geese.
- * @param {!number} alignCount The current number of geese that have
- *     contributed to the alignment component so far.
- * @return {!number} The new count of geese that contribute to the alignment
- *     component.  If the goose under consideration does not contribute, this
- *     value is the same as |alignCount|.
- * @private
- */
-Goose.prototype.accumulateAlignment_ = function(distance,
-                                                goose,
-                                                alignment,
-                                                alignCount) {
-  if (distance > 0 && distance < this.NEIGHBOUR_RADIUS) {
-    alignment.add(goose.velocity());
-    alignCount++;
-  }
-  return alignCount;
-}
-
-/**
- * Add a neighbouring goose's contribution to the cohesion mean.  Cohesion is
- * based on the average location of the neighbours.  The goose attempts to
- * point to this average location.  Only consider geese that are within
- * |NEIGHBOUR_RADIUS|.  Modifies the cohesion accumulator |cohesion| in-place.
- * @param {!number} distance The distance from this goose to the neighbouring
- *     goose.
- * @param {!Goose} goose The neighbouring goose under consideration.
- * @param {!goog.math.Vec2} cohesion The accumulated cohesion from all the
- *     neighbouring geese.
- * @param {!number} cohesionCount The current number of geese that have
- *     contributed to the cohesion component so far.
- * @return {!number} The new count of geese that contribute to the cohesion
- *     component.  If the goose under consideration does not contribute, this
- *     value is the same as |cohesionCount|.
- * @private
- */
-Goose.prototype.accumulateCohesion_ = function(distance,
-                                               goose,
-                                               cohesion,
-                                               cohesionCount) {
-  if (distance > 0 && distance < this.NEIGHBOUR_RADIUS) {
-    cohesion.add(goose.location());
-    cohesionCount++;
-  }
-  return cohesionCount;
-}
-
-/**
- * Turn the goose towards a target.  The amount of turning force is clamped
- * to |MAX_TURNING_FORCE|.
- * @param {!goog.math.Vec2} target Turn the goose towards this target.
- * @return {goog.math.Vec2} A vector representing the new direction of the
- *     goose.
- */
-Goose.prototype.turnTowardsTarget = function(target) {
-  var desiredDirection = goog.math.Vec2.difference(target, this.location_);
-  var distance = desiredDirection.magnitude();
-  var newDirection = new goog.math.Vec2(0, 0);
-  if (distance > 0) {
-    desiredDirection.normalize();
-    // If the target is within the turning affinity distance, then make the
-    // desired direction based on distance to the target.  Otherwise, base
-    // the desired direction on MAX_SPEED.
-    if (distance < this.MAX_TURNING_DISTANCE) {
-      // Some pretty arbitrary dampening.
-      desiredDirection.scale(this.MAX_SPEED * distance / 100.0);
-    } else {
-      desiredDirection.scale(this.MAX_SPEED);
-    }
-    newDirection = goog.math.Vec2.difference(desiredDirection, this.velocity_);
-    newDirection.clamp(this.MAX_TURNING_FORCE);
-  }
-  return newDirection;
-}
-
-/**
- * Clamp a vector to a maximum magnitude.  Works on the vector in-place.
- * @param {!goog.math.Vec2} v The vector.
- * @param {!number} max_mag The maximum magnitude of the vector.
- */
-goog.math.Vec2.prototype.clamp = function(max_mag) {
-  var mag = this.magnitude();
-  if (mag > max_mag && max_mag != 0) {
-    this.normalize();
-    this.scale(max_mag);
-  }
-}
-
-/**
- * Compute the "heading" of a vector - this is the angle in radians between
- * the vector and the x-axis.
- * @return {!number} The "heading" angle in radians.
- */
-goog.math.Vec2.prototype.heading = function() {
-  var angle = Math.atan2(this.y, this.x);
-  return angle;
-}
-