Add optional world input to canSee

flame-engine · Jul 21, 2023 · 76c1dae · 76c1dae
1 parent 2ee0282
commit 76c1dae
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Showing 2 changed files with 38 additions and 44 deletions.
diff --git a/packages/flame/lib/src/camera/camera_component.dart b/packages/flame/lib/src/camera/camera_component.dart
@@ -284,29 +284,24 @@ class CameraComponent extends Component {
   }
 
   /// Returns true if this camera is able to see the [component].
-  ///
-  /// Will return false if the component does not belong to the [world] this
-  /// camera is looking at.
-  ///
-  /// For components deeply nested in the world, consider use the [HasAncestor]
-  /// or [ParentIsA] mixin with [World] type to make the world lookup faster.
-  bool canSee(PositionComponent component) {
-    if (world == null || !component.isMounted) {
-      return false;
-    }
-
-    World? componentWorld;
-
-    // Try to find which world the given component belongs to.
-    if (component is ParentIsA<World>) {
-      componentWorld = (component as ParentIsA<World>).parent;
-    } else if (component is HasAncestor<World>) {
-      componentWorld = (component as HasAncestor<World>).ancestor;
-    } else {
-      componentWorld = component.findParent<World>();
-    }
-
-    if (world != componentWorld) {
+  /// 
+  /// Will always return false if
+  /// - [world] is null or 
+  /// - [world] is not mounted or
+  /// - [component] is not mounted or
+  /// - [componentWorld] is non-null and does not match with [world]
+  /// 
+  /// If [componentWorld] is null, this method does not take into consideration
+  /// the world to which the given [component] belongs (if any). This means, in
+  /// such cases, any component overlapping the [visibleWorldRect] will be
+  /// reported as visible, even if it is not part of the [world] this camera is
+  /// currently looking at. This can be changed by passing the the component's 
+  /// world as [componentWorld].
+  bool canSee(PositionComponent component, {World? componentWorld}) {
+    if (world == null ||
+        !world!.isMounted ||
+        !component.isMounted ||
+        (componentWorld != null && componentWorld != world)) {
       return false;
     }
 

diff --git a/packages/flame/test/camera/camera_component_test.dart b/packages/flame/test/camera/camera_component_test.dart
@@ -326,45 +326,48 @@ void main() {
       expect(camera.canSee(player), true);
     });
 
-    testWithFlameGame('unmounted component', (game) async {
+    testWithFlameGame('unmounted world', (game) async {
       final player = PositionComponent();
-      final world = World();
+      final world = World(children: [player]);
       final camera = CameraComponent(world: world);
 
-      await game.addAll([camera, world]);
+      await game.addAll([camera]);
       await game.ready();
       expect(camera.canSee(player), false);
 
-      await world.add(player);
+      await game.add(world);
       await game.ready();
       expect(camera.canSee(player), true);
     });
 
-    testWithFlameGame('component with parent world', (game) async {
-      final player = _ParentIsAWorld();
-      final world = World(children: [player]);
-      final camera = CameraComponent();
+    testWithFlameGame('unmounted component', (game) async {
+      final player = PositionComponent();
+      final world = World();
+      final camera = CameraComponent(world: world);
 
       await game.addAll([camera, world]);
       await game.ready();
       expect(camera.canSee(player), false);
 
-      camera.world = world;
+      await world.add(player);
+      await game.ready();
       expect(camera.canSee(player), true);
     });
 
-    testWithFlameGame('component with ancestor world', (game) async {
-      final player = _HasAncestorWorld();
-      final level = PositionComponent(children: [player]);
-      final world = World(children: [level]);
-      final camera = CameraComponent();
+    testWithFlameGame('component from another world', (game) async {
+      final player = PositionComponent();
+      final world1 = World(children: [player]);
+      final world2 = World();
+      final camera = CameraComponent(world: world2);
 
-      await game.addAll([camera, world]);
+      await game.addAll([camera, world1, world2]);
       await game.ready();
-      expect(camera.canSee(player), false);
 
-      camera.world = world;
+      // can see when player world is not known.
       expect(camera.canSee(player), true);
+
+      // can't see when the player world is known.
+      expect(camera.canSee(player, componentWorld: world1), false);
     });
   });
 }
@@ -375,7 +378,3 @@ class _SolidBackground extends Component with HasPaint {
   @override
   void render(Canvas canvas) => canvas.drawColor(color, BlendMode.src);
 }
-
-class _HasAncestorWorld extends PositionComponent with HasAncestor<World> {}
-
-class _ParentIsAWorld extends PositionComponent with ParentIsA<World> {}