feat: adding character base class (#35)

examples/standard_platformer/lib/main.dart

@@ -93,7 +93,7 @@ class ExamplePlatformerLeapGame extends LeapGame
     );
 
     player = Player();
-    world.add(player = Player());
+    world.add(player!);
     camera.follow(player!);
 
     if (!FlameAudio.bgm.isPlaying) {

examples/standard_platformer/lib/player.dart

@@ -8,7 +8,7 @@ import 'package:leap_standard_platformer/info_text.dart';
 import 'package:leap_standard_platformer/main.dart';
 
 class Player extends JumperCharacter<ExamplePlatformerLeapGame> {
-  Player({super.health = initialHealth}) {
+  Player({super.health = initialHealth}) : super(removeOnDeath: false) {
     solidTags.add(CommonTags.ground);
   }
 
@@ -113,7 +113,7 @@ class Player extends JumperCharacter<ExamplePlatformerLeapGame> {
     }
 
     final ladderCollision =
-        collisionInfo.allCollisions?.whereType<Ladder>().firstOrNull;
+        collisionInfo.allCollisions.whereType<Ladder>().firstOrNull;
     final onLadderStatus = getStatus<OnLadderStatus>();
     if (_input.justPressed &&
         _input.isPressedCenter &&
@@ -240,7 +240,7 @@ class Player extends JumperCharacter<ExamplePlatformerLeapGame> {
       velocity.y = -minJumpImpulse;
     }
 
-    for (final other in collisionInfo.allCollisions ?? const []) {
+    for (final other in collisionInfo.allCollisions) {
       if (other is Coin) {
         other.removeFromParent();
         coins++;

examples/standard_platformer/pubspec.lock

@@ -201,7 +201,7 @@ packages:
       path: "../../packages/leap"
       relative: true
     source: path
-    version: "0.3.1"
+    version: "0.4.0"
   material_color_utilities:
     dependency: transitive
     description:

packages/leap/lib/src/characters/jumper_character.dart

@@ -1,11 +1,12 @@
 import 'package:flame/components.dart';
 import 'package:leap/src/characters/jumper_behavior.dart';
-import 'package:leap/src/entities/entities.dart';
+import 'package:leap/src/entities/character.dart';
 import 'package:leap/src/leap_game.dart';
 
-class JumperCharacter<TGame extends LeapGame> extends PhysicalEntity<TGame> {
+class JumperCharacter<TGame extends LeapGame> extends Character<TGame> {
   JumperCharacter({
     super.health = 10,
+    super.removeOnDeath,
   }) : super(behaviors: [JumperBehavior()]);
 
   /// When true the character is facing left, otherwise right.

packages/leap/lib/src/entities/character.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/foundation.dart';
+import 'package:leap/leap.dart';
+
+/// A type of [PhysicalEntity] which is typically used as the base class
+/// for players, enemies, etc.
+/// Characters have health, and usually a removed on death.
+///
+// TODO(kurtome): add sprite animation and state helpers.
+class Character<T extends LeapGame> extends PhysicalEntity<T> {
+  Character({
+    this.health = 1,
+    this.removeOnDeath = true,
+    super.static,
+    super.behaviors,
+    super.priority,
+    super.position,
+    super.size,
+  }) : super() {
+    _wasAlive = isAlive;
+  }
+
+  /// The health of this character, when positive this is "alive".
+  int health;
+
+  /// Indicates if this should [remove] itself on death.
+  bool removeOnDeath;
+
+  /// Whether or not this is "alive" (or not destroyed) in the game
+  bool get isAlive => health > 0;
+
+  /// Whether or not this is "dead" (or destroyed) in the game.
+  bool get isDead => !isAlive;
+
+  bool _wasAlive = true;
+
+  /// Indicates that this was alive on the previous [update] loop
+  bool get wasAlive => _wasAlive;
+
+  /// Called when this entity dies, typically due to health dropping below one.
+  ///
+  /// This will be invoked after this has been marked for removal
+  /// (if [removeOnDeath] is true) but before [onRemove].
+  /// Entities can be removed without dying.
+  @mustCallSuper
+  void onDeath() {}
+
+  @override
+  @mustCallSuper
+  void update(double dt) {
+    super.update(dt);
+
+    if (isDead && wasAlive) {
+      if (removeOnDeath) {
+        removeFromParent();
+      }
+      onDeath();
+    }
+
+    _wasAlive = isAlive;
+  }
+}

packages/leap/lib/src/entities/ladder.dart

@@ -65,8 +65,7 @@ class OnLadderStatus<T extends LeapGame> extends StatusComponent
 
     final parentEntity = parent! as PhysicalEntity;
 
-    if (!(parentEntity.collisionInfo.allCollisions?.contains(ladder) ??
-        false)) {
+    if (!parentEntity.collisionInfo.allCollisions.contains(ladder)) {
       // No longer on the ladder
       removeFromParent();
       parentEntity.velocity.y = 0;

packages/leap/lib/src/entities/physical_entity.dart

@@ -51,12 +51,7 @@ abstract class PhysicalEntity<TGame extends LeapGame> extends PositionedEntity
   /// Multiplier on standard gravity, see [LeapWorld].
   double gravityRate = 1;
 
-  /// When health reaches 0, [isDead] will be true.
-  /// This needs to be used by child classes to have any effect.
-  int health;
-
   PhysicalEntity({
-    this.health = 10,
     this.static = false,
     Iterable<Behavior<PhysicalEntity>>? behaviors,
     super.priority,
@@ -121,12 +116,6 @@ abstract class PhysicalEntity<TGame extends LeapGame> extends PositionedEntity
   /// Tile size (width and height) in pixels
   double get tileSize => game.tileSize;
 
-  /// Whether or not this is "alive" (or not destroyed) in the game
-  bool get isAlive => health > 0;
-
-  /// Whether or not this is "dead" (or destroyed) in the game.
-  bool get isDead => !isAlive;
-
   /// Leftmost point.
   double get left {
     return x;

packages/leap/lib/src/physical_behaviors/collision/collision_detection_behavior.dart

@@ -127,7 +127,7 @@ class CollisionDetectionBehavior extends PhysicalBehavior {
         !collisionInfo.onSlope) {
       // Moving down.
       _calculateSolidHits((c) {
-        return c.bottom >= bottom &&
+        return c.bottom > bottom &&
             c.isSolidFromTop &&
             // For one-way platforms from underneath, make sure this is
             // currently above it so this doesn't pop up on top of it
@@ -292,7 +292,7 @@ class CollisionDetectionBehavior extends PhysicalBehavior {
 
     _proxyHitboxForPotentialHits(dt);
     for (final other in world.physicals) {
-      if (intersectsOther(_hitboxProxy, other)) {
+      if (!other.isRemoving && intersectsOther(_hitboxProxy, other)) {
         _potentialHits.add(other);
       }
     }

packages/leap/lib/src/physical_behaviors/collision/collision_info.dart

@@ -32,7 +32,7 @@ class CollisionInfo {
 
   set upCollision(PhysicalEntity? c) {
     if (_upCollision != null) {
-      allCollisions?.remove(c);
+      _allCollisions?.remove(c);
     }
     if (c != null) {
       addCollision(c);
@@ -45,7 +45,7 @@ class CollisionInfo {
 
   set downCollision(PhysicalEntity? c) {
     if (_downCollision != null) {
-      allCollisions?.remove(c);
+      _allCollisions?.remove(c);
     }
     if (c != null) {
       addCollision(c);
@@ -58,7 +58,7 @@ class CollisionInfo {
 
   set leftCollision(PhysicalEntity? c) {
     if (_leftCollision != null) {
-      allCollisions?.remove(c);
+      _allCollisions?.remove(c);
     }
     if (c != null) {
       addCollision(c);
@@ -71,7 +71,7 @@ class CollisionInfo {
 
   set rightCollision(PhysicalEntity? c) {
     if (_rightCollision != null) {
-      allCollisions?.remove(c);
+      _allCollisions?.remove(c);
     }
     if (c != null) {
       addCollision(c);
@@ -80,11 +80,13 @@ class CollisionInfo {
   }
 
   /// Non-solid collisions.
-  List<PhysicalEntity>? allCollisions;
+  List<PhysicalEntity>? _allCollisions;
+
+  List<PhysicalEntity> get allCollisions => _allCollisions ?? const [];
 
   void addCollision(PhysicalEntity collision) {
-    allCollisions ??= [];
-    allCollisions!.add(collision);
+    _allCollisions ??= [];
+    _allCollisions!.add(collision);
   }
 
   /// Is currently colliding on top
@@ -115,7 +117,8 @@ class CollisionInfo {
     downCollision = null;
     leftCollision = null;
     rightCollision = null;
-    allCollisions = null;
+
+    _allCollisions = null;
   }
 
   void copyFrom(CollisionInfo other) {
@@ -124,10 +127,10 @@ class CollisionInfo {
     _leftCollision = other.leftCollision;
     _rightCollision = other.rightCollision;
 
-    allCollisions?.clear();
-    if (other.allCollisions != null) {
-      allCollisions ??= [];
-      allCollisions!.addAll(other.allCollisions!);
+    _allCollisions?.clear();
+    if (other.allCollisions.isNotEmpty) {
+      _allCollisions ??= [];
+      _allCollisions!.addAll(other.allCollisions);
     }
   }
 }