Physics Engine (#4)

* Add matter-js as a dependency

* Add body component

* Fix renderable node doc

* Add the physics node type

* Correct typo in physics enabled node types

* Update docs on render system

* Add physics system

* Update changelog

* Add physics engine to main app

* Tweak the gravity of the world

* Add body to sumo factory

* Add angle component

* Add angle to entity

* Add angle to the nodes

* Pass angle between systems

* Set default angle to 0

* Split systems and nodes

* Fix indentaion in physics world control

* Add third sumo entity

* Adjust values for constriants and physics

* Correct docs in new nodes

* Update built-in docs

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/systems/create_coupling_line.js b/lib/systems/create_coupling_line.js
new file mode 100644
index 0000000..8e5e9d7
--- /dev/null
+++ b/lib/systems/create_coupling_line.js
@@ -0,0 +1,96 @@
+import { System } from '@serpentity/serpentity';
+import { Graphics } from 'pixi.js';
+
+import PositionComponent from '@serpentity/components.position';
+
+import RenderableCoupleNode from '../nodes/renderable_couple';
+
+/**
+ * Renders renderable objects using pixi
+ *
+ * @extends {external:Serpentity.System}
+ * @class CreateCouplingLineSystem
+ * @param {object} config a configuration object to extend.
+ */
+export default class CreateCouplingLineSystem extends System {
+
+  constructor(config = {}) {
+
+    super();
+
+    /**
+     * The node collection of coupled entities entities
+     *
+     * @property {external:Serpentity.NodeCollection} coupledEntities
+     * @instance
+     * @memberof CreateCouplingLineSystem
+     */
+    this.coupledEntities = null;
+  }
+
+  /**
+   * Initializes system when added. Requests renderable nodes and
+   *
+   * @function added
+   * @memberof CreateCouplingLineSystem
+   * @instance
+   * @param {external:Serpentity.Engine} engine the serpentity engine to
+   * which we are getting added
+   */
+  added(engine) {
+
+    this.coupledEntities = engine.getNodes(RenderableCoupleNode);
+  }
+
+  /**
+   * Clears system resources when removed.
+   *
+   * @function removed
+   * @instance
+   * @memberof CreateCouplingLineSystem
+   */
+  removed() {
+
+    this.coupledEntities = null;
+  }
+
+  /**
+   * Runs on every update of the loop. Does nothing.
+   *
+   * @function update
+   * @instance
+   * @param {Number} currentFrameDuration the duration of the current
+   * frame
+   * @memberof CreateCouplingLineSystem
+   */
+  update(currentFrameDuration) {
+
+    for (const rootEntity of this.coupledEntities) {
+
+      const rootGraphic = rootEntity.container.container;
+      rootGraphic.removeChildren();
+
+      let lineGraphic = new Graphics();
+      lineGraphic = lineGraphic.lineStyle(5, 0xffffff, 0.9);
+
+      let initialPosition = false;
+
+      for (const coupledEntity of rootEntity.coupledEntities.coupledEntities) {
+        if (coupledEntity.hasComponent(PositionComponent)) {
+
+          const position = coupledEntity.getComponent(PositionComponent);
+
+          if (!initialPosition) {
+            lineGraphic = lineGraphic.moveTo(position.x, position.y);
+            initialPosition = true;
+            continue;
+          }
+          lineGraphic = lineGraphic.lineTo(position.x, position.y);
+        }
+      }
+
+      rootGraphic.addChild(lineGraphic);
+    }
+  }
+};
+