1 files changed, 49 insertions, 0 deletions
diff --git a/src/systems/collision.js b/src/systems/collision.js
new file mode 100644
index 0000000..7739bae
--- /dev/null
+++ b/src/systems/collision.js
@@ -0,0 +1,49 @@
+game.system.Collision = (entitiesGrid) => {
+  const update = (elapsedTime, entities, changedIds) => {
+    for (let entity of Object.keys(entities).map((id) => entities[id])) {
+      if (entity.hasComponent("controllable") && entity.hasComponent("gridPosition") && entity.hasComponent("momentum")) {
+        const momentum = unitize(entity.components.momentum);
+
+        let found;
+        const proposed = {x: entity.components.gridPosition.x + momentum.dx, y: entity.components.gridPosition.y + momentum.dy};
+        const entitiesToPush = [];
+        let wall = false;
+        do {
+          const proposedClampedInBounds = clamp(proposed, game.config.xDim-1, game.config.yDim-1);
+          if (!equivalence(proposed, proposedClampedInBounds)) {
+            break;
+          }
+
+          found = false;
+
+          const entitiesInCell = entitiesGrid[proposed.y][proposed.x];
+
+          for (let next of entitiesInCell.values()) {
+            if (next.hasComponent("stop")) {
+              console.log("WALL FOUND")
+              wall = next;
+              found = false;
+              break;
+            }
+            if (next.hasComponent("pushable")) {
+              entitiesToPush.push(next);
+              found = true;
+            }
+          }
+
+          proposed.x += momentum.dx;
+          proposed.y += momentum.dy;
+        } while(found);
+
+        if (wall) {
+          console.log("WALL")
+          entity.removeComponent("momentum");
+        } else {
+          entitiesToPush.map((e) => e.addComponent(game.components.Momentum({...momentum})));
+        }
+      }
+    }
+    return new Set();
+  };
+  return { update };
+};