Add Naive Game Rules (#11)

* Add components for tracking points

* Add methods to create new entities

* Adds nodes for points

* Add system to detect points

* Adds system to detect a winner

* Add system to render points and winner

* Add points required to win to config

* Add it all to the engine

* Add mention of points to changelog

1 files changed, 100 insertions, 0 deletions

diff --git a/lib/systems/detect_points_collision.js b/lib/systems/detect_points_collision.js
new file mode 100644
index 0000000..c84f3fc
--- /dev/null
+++ b/lib/systems/detect_points_collision.js
@@ -0,0 +1,100 @@
+import { System } from '@serpentity/serpentity';
+import { SAT } from 'matter-js';
+
+import BodyComponent from '../components/body';
+import PointsColliderNode from '../nodes/points_collider';
+import PointsNode from '../nodes/points';
+
+/**
+ * Handles grabbing between entities
+ *
+ * @extends {external:Serpentity.System}
+ * @class DetectPointsCollisionSystem
+ * @param {object} config a configuration object to extend.
+ */
+export default class DetectPointsCollisionSystem extends System {
+
+  constructor(config = {}) {
+
+    super();
+
+    /**
+     * The collection of points colliders
+     *
+     * @property {external:Serpentity.NodeCollection} pointsColliders
+     * @instance
+     * @memberof DetectPointsCollisionSystem
+     */
+    this.pointsColliders = null;
+
+    /**
+     * The collection of points keepers
+     *
+     * @property {external:Serpentity.NodeCollection} pointsKeepers
+     * @instance
+     * @memberof DetectPointsCollisionSystem
+     */
+    this.pointsKeepers = null;
+  }
+
+  /**
+   * Initializes system when added. Requests points colliders and points
+   * accumulators
+   *
+   * @function added
+   * @memberof DetectPointsCollisionSystem
+   * @instance
+   * @param {external:Serpentity.Engine} engine the serpentity engine to
+   * which we are getting added
+   */
+  added(engine) {
+
+    this.pointsCollider = engine.getNodes(PointsColliderNode);
+    this.pointsKeepers = engine.getNodes(PointsNode);
+  }
+
+  /**
+   * Clears system resources when removed.
+   *
+   * @function removed
+   * @instance
+   * @memberof DetectPointsCollisionSystem
+   */
+  removed() {
+
+    this.pointsCollider = null;
+    this.pointsKeepers = null;
+  }
+
+  /**
+   * Runs on every update of the loop. Triggers grab and manages cooldown
+   *
+   * @function update
+   * @instance
+   * @param {Number} currentFrameDuration the duration of the current
+   * frame
+   * @memberof DetectPointsCollisionSystem
+   */
+  update(currentFrameDuration) {
+
+    const points = {};
+
+    for (const collider of this.pointsCollider) {
+      const collisionTargetBody = collider.pointsCollider.collisionTarget.getComponent(BodyComponent);
+      const pointsTarget = collider.pointsCollider.pointsTarget;
+
+      if (collisionTargetBody) {
+        const collision = SAT.collides(collider.body.body, collisionTargetBody.body);
+        if (collision.collided) {
+          points[pointsTarget] = (points[pointsTarget] || 0) + 1;
+        }
+      }
+    }
+
+    for (const pointsKeeper of this.pointsKeepers) {
+      for (const pointsLabel of Object.keys(points)) {
+        pointsKeeper.points[pointsLabel] = (pointsKeeper.points[pointsLabel] || 0) + points[pointsLabel];
+      }
+    }
+  }
+};