git.r.bdr.sh - rbdr/sumo/blob - lib/systems/apply_force.js

   1 import { System } from '@serpentity/serpentity';
   2 import { Body, Vector } from 'matter-js';
   3
   4 const internals = {
   5   kForce: 0.0001
   6 };
   7
   8 import PhysicalWithExternalForceNode from '../nodes/physical_with_external_force';
   9
  10 /**
  11  * Applies physica from external forces (eg. controls) to the physics body
  12  *
  13  * @extends {external:Serpentity.System}
  14  * @class ApplyForceSystem
  15  * @param {object} config a configuration object to extend.
  16  */
  17 export default class ApplyForceSystem extends System {
  18
  19   constructor(config = {}) {
  20
  21     super();
  22
  23     /**
  24      * The node collection of entities that have external force
  25      *
  26      * @property {external:Serpentity.NodeCollection} physicalEntities
  27      * @instance
  28      * @memberof ApplyForceSystem
  29      */
  30     this.physicalEntities = null;
  31   }
  32
  33   /**
  34    * Initializes system when added. Requests physics nodes
  35    *
  36    * @function added
  37    * @memberof ApplyForceSystem
  38    * @instance
  39    * @param {external:Serpentity.Engine} engine the serpentity engine to
  40    * which we are getting added
  41    */
  42   added(engine) {
  43
  44     this.physicalEntities = engine.getNodes(PhysicalWithExternalForceNode);
  45   }
  46
  47   /**
  48    * Clears system resources when removed.
  49    *
  50    * @function removed
  51    * @instance
  52    * @memberof ApplyForceSystem
  53    */
  54   removed() {
  55
  56     this.physicalEntities = null;
  57   }
  58
  59   /**
  60    * Runs on every update of the loop. Updates the body based on the force
  61    * component
  62    *
  63    * @function update
  64    * @instance
  65    * @param {Number} currentFrameDuration the duration of the current
  66    * frame
  67    * @memberof ApplyForceSystem
  68    */
  69   update(currentFrameDuration) {
  70
  71     for (const physicalEntity of this.physicalEntities) {
  72       const body = physicalEntity.body.body;
  73       const force = physicalEntity.force;
  74       const forceVector = Vector.create(force.x * internals.kForce, force.y * internals.kForce);
  75
  76
  77       // Store the last angle and apply force on non-zero forces
  78
  79       if (force.x || force.y) {
  80         force.lastAngle = Math.atan2(force.y, force.x);
  81         Body.applyForce(body,
  82           {
  83             x: body.position.x,
  84             y: body.position.y
  85           },
  86           forceVector
  87         );
  88       }
  89
  90       // Reset the force
  91
  92       force.x = 0;
  93       force.y = 0;
  94     }
  95   }
  96 };
  97