feat: smoother camera movement (#185)

lib/game/components/player_camera_anchor.dart

@@ -1,17 +1,131 @@
 import 'package:flame/components.dart';
 import 'package:flame/effects.dart';
+import 'package:flutter/material.dart';
+import 'package:super_dash/game/super_dash_game.dart';
+
+class CameraBounds extends PositionComponent {
+  CameraBounds({
+    required this.reference,
+    required this.bound,
+    this.showBounds = false,
+  });
+
+  final PositionComponent reference;
+  final double bound;
+  final bool showBounds;
+
+  late final Vector2 referenceOffset;
+
+  double translateValue = 0;
+  double translatedValue = 0;
+
+  void _updatePosition(double dt) {
+    position.x = reference.position.x + referenceOffset.x;
+
+    final playerPosition = reference.position.y + referenceOffset.y;
+    final difference = playerPosition - position.y;
+    if (difference.abs() > bound) {
+      translateValue = difference;
+    }
+
+    if (translateValue.abs() > 0) {
+      final translationDifference =
+          (translateValue.abs() - translatedValue.abs()) / translateValue.abs();
+      var speed = 1.0 - translationDifference;
+      speed = 1 - speed * speed * speed * speed;
+
+      final step = (800 * speed) * dt * translateValue.sign;
+
+      position.y += step;
+      translatedValue += step.abs();
+
+      if (translateValue.abs() - translatedValue.abs() < 10) {
+        translateValue = 0;
+        translatedValue = 0;
+      }
+    }
+  }
+
+  @override
+  void onMount() {
+    super.onMount();
+
+    referenceOffset = Vector2(
+      reference.size.x,
+      reference.size.y,
+    );
+    position.y = reference.position.y + referenceOffset.y;
+
+    _updatePosition(0);
+
+    if (showBounds) {
+      const referenceLine = 150.0;
+      add(
+        RectangleComponent(
+          position: Vector2(
+            -referenceLine / 2,
+            -bound,
+          ),
+          size: Vector2(
+            referenceLine,
+            2,
+          ),
+          paint: Paint()..color = Colors.red,
+        ),
+      );
+
+      add(
+        RectangleComponent(
+          position: Vector2(
+            -referenceLine / 2,
+            0,
+          ),
+          size: Vector2(
+            referenceLine,
+            2,
+          ),
+          paint: Paint()..color = Colors.green,
+        ),
+      );
+
+      add(
+        RectangleComponent(
+          position: Vector2(
+            -referenceLine / 2,
+            bound,
+          ),
+          size: Vector2(
+            referenceLine,
+            2,
+          ),
+          paint: Paint()..color = Colors.red,
+        ),
+      );
+    }
+  }
+
+  @override
+  void update(double dt) {
+    super.update(dt);
+
+    _updatePosition(dt);
+  }
+}
 
 class PlayerCameraAnchor extends Component
-    with ParentIsA<PositionComponent>
+    with ParentIsA<PositionComponent>, HasGameRef<SuperDashGame>
     implements ReadOnlyPositionProvider {
   PlayerCameraAnchor({
     required this.levelSize,
     required this.cameraViewport,
+    this.showCameraBounds = false,
   });
 
   final Vector2 levelSize;
   final Vector2 cameraViewport;
   final Vector2 _anchor = Vector2.zero();
+  late final PositionComponent _bounds;
+  final bool showCameraBounds;
 
   late final Vector2 _cameraMin = Vector2(
     cameraViewport.x * .4,
@@ -36,8 +150,15 @@ class PlayerCameraAnchor extends Component
   }
 
   @override
-  Future<void> onLoad() async {
-    await super.onLoad();
+  void onMount() {
+    super.onMount();
+
+    _bounds = CameraBounds(
+      reference: parent,
+      bound: 128,
+      showBounds: showCameraBounds,
+    );
+    gameRef.world.add(_bounds);
 
     final value = parent.position.clone();
     _setAnchor(value.x, value.y);
@@ -48,8 +169,8 @@ class PlayerCameraAnchor extends Component
     super.update(dt);
 
     _setAnchor(
-      parent.position.x,
-      parent.position.y,
+      _bounds.position.x,
+      _bounds.position.y,
     );
   }
 }

lib/game/entities/player.dart

@@ -94,6 +94,7 @@ class Player extends JumperCharacter<SuperDashGame> {
     cameraAnchor = PlayerCameraAnchor(
       cameraViewport: cameraViewport,
       levelSize: levelSize,
+      showCameraBounds: gameRef.inMapTester,
     );
 
     add(cameraAnchor);