1 files changed, 61 insertions, 0 deletions
diff --git a/src/engine/systems/RadialObserve.ts b/src/engine/systems/RadialObserve.ts
new file mode 100644
index 0000000..8d418df
--- /dev/null
+++ b/src/engine/systems/RadialObserve.ts
@@ -0,0 +1,61 @@
+import { System, SystemNames } from ".";
+import { ComponentNames, Grid, RadialObserve } from "../components";
+import { Entity, EntityNames } from "../entities";
+import { Game } from "../Game";
+import { cartesianDistance } from "../interfaces";
+
+const radialObservations: Record<string, Set<string>> = {
+  TODO: new Set([]),
+};
+
+export class RadialObserver extends System {
+  constructor() {
+    super(SystemNames.RadialObserver);
+  }
+
+  public update(_dt: number, game: Game) {
+    game.forEachEntityWithComponent(ComponentNames.RadialObserve, (entity) => {
+      if (!(entity.name in radialObservations)) {
+        return;
+      }
+      const observable = radialObservations[entity.name];
+
+      const entityObserve = entity.getComponent<RadialObserve>(
+        ComponentNames.RadialObserve,
+      );
+      if (!entityObserve.onObservation) {
+	return;
+      }
+
+      const entityPosition = entity.getComponent<Grid>(
+        ComponentNames.Grid,
+      ).gridPosition;
+
+      const observations: Entity[] = [];
+      game.forEachEntityWithComponent(ComponentNames.RadialObserve, (other) => {
+        if (entity === other) {
+          return;
+        }
+        if (!observable.has(other.name)) {
+          return;
+        }
+
+        const otherPosition = other.getComponent<Grid>(
+          ComponentNames.Grid,
+        ).gridPosition;
+        if (
+          cartesianDistance(entityPosition, otherPosition) >
+          entityObserve.radius
+        ) {
+          return;
+        }
+
+        observations.push(other);
+      });
+
+      for (const observation of observations) {
+	entityObserve.onObservation!(game, observation);
+      }
+    });
+  }
+}