fieldkit/lib/physics/constraints.js

Basic building blocks for computational design projects. Written in CoffeeScript for browser and server environments.

// Generated by CoffeeScript 1.6.3
(function() {
  var Area, Box, Collision, Constraint, Vec2, Vec3, Wrap2, Wrap3, physics, vector,
    __hasProp = {}.hasOwnProperty,
    __extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };

  vector = require('../math/vector');

  Vec2 = vector.Vec2;

  Vec3 = vector.Vec3;

  physics = require('./physics');

  Constraint = physics.Constraint;

  /*
    Keeps the particle inside the given 3D box
  */


  Box = (function(_super) {
    __extends(Box, _super);

    function Box(min, max) {
      this.min = min != null ? min : new Vec3();
      this.max = max != null ? max : new Vec3(100, 100, 100);
    }

    Box.prototype.apply = function(particle) {
      var pos;
      pos = particle.position;
      if (pos.x < this.min.x) {
        pos.x = this.min.x;
      }
      if (pos.y < this.min.y) {
        pos.y = this.min.y;
      }
      if (pos.z < this.min.z) {
        pos.z = this.min.z;
      }
      if (pos.x > this.max.x) {
        pos.x = this.max.x;
      }
      if (pos.y > this.max.y) {
        pos.y = this.max.y;
      }
      if (pos.z > this.max.z) {
        return pos.z = this.max.z;
      }
    };

    Box.prototype.toString = function() {
      return "Box(" + this.min + ", " + this.max + ")";
    };

    return Box;

  })(Constraint);

  /*
    2D version of Box.
  */


  Area = (function(_super) {
    __extends(Area, _super);

    function Area(min, max) {
      this.min = min != null ? min : new Vec2();
      this.max = max != null ? max : new Vec2(100, 100);
    }

    Area.prototype.apply = function(particle) {
      var pos;
      pos = particle.position;
      if (pos.x < this.min.x) {
        pos.x = this.min.x;
      }
      if (pos.y < this.min.y) {
        pos.y = this.min.y;
      }
      if (pos.x > this.max.x) {
        pos.x = this.max.x;
      }
      if (pos.y > this.max.y) {
        return pos.y = this.max.y;
      }
    };

    Area.prototype.toString = function() {
      return "Area(" + this.min + ", " + this.max + ")";
    };

    return Area;

  })(Constraint);

  /*
    Keeps a particle within a certain 2D region by wrapping it around a given area.
  */


  Wrap2 = (function(_super) {
    var delta;

    __extends(Wrap2, _super);

    delta = new Vec2();

    function Wrap2(min, max) {
      this.min = min != null ? min : new Vec2();
      this.max = max != null ? max : new Vec2(100, 100);
    }

    Wrap2.prototype.prepare = function() {
      return delta.set(this.max).sub(this.min);
    };

    Wrap2.prototype.apply = function(particle) {
      var pos, prev;
      pos = particle.position;
      prev = particle.prev;
      if (pos.x < this.min.x) {
        pos.x += delta.x;
        prev.x += delta.x;
      }
      if (pos.y < this.min.y) {
        pos.y += delta.y;
        prev.y += delta.y;
      }
      if (pos.x > this.max.x) {
        pos.x -= delta.x;
        prev.x -= delta.x;
      }
      if (pos.y > this.max.y) {
        pos.y -= delta.y;
        return prev.y -= delta.y;
      }
    };

    Wrap2.prototype.toString = function() {
      return "Wrap2(" + this.min + ", " + this.max + ")";
    };

    return Wrap2;

  })(Constraint);

  /*
    Keeps a particle within a certain 2D region by wrapping it around a given area.
  */


  Wrap3 = (function(_super) {
    var delta;

    __extends(Wrap3, _super);

    delta = new Vec3();

    function Wrap3(min, max) {
      this.min = min != null ? min : new Vec3();
      this.max = max != null ? max : new Vec3(100, 100, 100);
    }

    Wrap3.prototype.prepare = function() {
      return delta.set(this.max).sub(this.min);
    };

    Wrap3.prototype.apply = function(particle) {
      var pos, prev;
      pos = particle.position;
      prev = particle.prev;
      if (pos.x < this.min.x) {
        pos.x += delta.x;
        prev.x += delta.x;
      }
      if (pos.y < this.min.y) {
        pos.y += delta.y;
        prev.y += delta.y;
      }
      if (pos.z < this.min.z) {
        pos.z += delta.z;
        prev.z += delta.z;
      }
      if (pos.x > this.max.x) {
        pos.x -= delta.x;
        prev.x -= delta.x;
      }
      if (pos.y > this.max.y) {
        pos.y -= delta.y;
        prev.y -= delta.y;
      }
      if (pos.z > this.max.z) {
        pos.z -= delta.z;
        return prev.z -= delta.z;
      }
    };

    Wrap3.prototype.toString = function() {
      return "Wrap3(" + this.min + ", " + this.max + ")";
    };

    return Wrap3;

  })(Constraint);

  /*
    Stops particles from colliding with each other.
  */


  Collision = (function(_super) {
    __extends(Collision, _super);

    Collision.prototype.physics = null;

    function Collision(physics, searchRadius) {
      this.physics = physics;
      this.searchRadius = searchRadius != null ? searchRadius : 100;
    }

    Collision.prototype.apply = function(particle) {
      var delta, dist, distSq, neighbour, neighbours, position, radius, radiusSq, _i, _len;
      position = particle.position;
      delta = position.clone();
      neighbours = this.physics.space.search(position, this.searchRadius);
      for (_i = 0, _len = neighbours.length; _i < _len; _i++) {
        neighbour = neighbours[_i];
        if (neighbour === particle) {
          continue;
        }
        delta.set(position).sub(neighbour.position);
        distSq = delta.lengthSquared();
        radius = particle.size + neighbour.size;
        radiusSq = radius * radius;
        if (distSq < radiusSq) {
          dist = Math.sqrt(distSq);
          delta.scale((dist - radius) / radius * 0.5);
          particle.position.sub(delta);
          neighbour.position.add(delta);
        }
        void 0;
      }
      return void 0;
    };

    Collision.prototype.toString = function() {
      return "Collision(" + this.searchRadius + ")";
    };

    return Collision;

  })(Constraint);

  module.exports = {
    Box: Box,
    Area: Area,
    Wrap2: Wrap2,
    Wrap3: Wrap3,
    Collision: Collision
  };

}).call(this);