add collision detection

lib/asteroid.dart

@@ -9,9 +9,9 @@ class Asteroid {
     required this.size,
     required this.position,
     this.speed = 0.5,
-    double radius = 50,
+    this.radius = 50,
   }) {
-    _radius = Random().nextDouble() * radius / 2 + radius / 2;
+    radius = Random().nextDouble() * radius / 2 + radius / 2;
 
     for (int i = 0; i < _totalVertices; i++) {
       _verticesOffset.add(Random().nextInt(radius ~/ 2) - radius / 4);
@@ -25,14 +25,15 @@ class Asteroid {
   Vector position;
 
   Vector _velocity = Vector.zero();
-  late final double _radius;
+  double radius;
+
   final int _totalVertices = Random().nextInt(10) + 5;
   final List<double> _verticesOffset = <double>[];
 
   void update() {
     position += _velocity;
 
-    position = wrapEdges(position, _radius, size);
+    position = wrapEdges(position, radius, size);
   }
 
   void render(Canvas canvas) {
@@ -56,7 +57,7 @@ class Asteroid {
     for (int i = 0; i < _totalVertices; i++) {
       final double angle = 2 * pi * i / _totalVertices;
       final Vector vertex =
-          Vector.fromAngle(angle) * (_radius + _verticesOffset[i]);
+          Vector.fromAngle(angle) * (radius + _verticesOffset[i]);
 
       points.add(vertex.toOffset);
     }

lib/helpers.dart

@@ -22,3 +22,14 @@ bool isOffScreen(Vector position, double radius, Size size) =>
     position.x > size.width + radius ||
     position.y < -radius ||
     position.y > size.height + radius;
+
+bool isColliding({
+  required Vector positionA,
+  required double radiusA,
+  required Vector positionB,
+  required double radiusB,
+}) {
+  final double distance = (positionA - positionB).magnitude;
+
+  return distance < radiusA + radiusB;
+}

lib/main.dart

@@ -4,6 +4,7 @@ import 'dart:math';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_asteroids/asteroid.dart';
+import 'package:flutter_asteroids/helpers.dart';
 import 'package:flutter_asteroids/playground.dart';
 import 'package:flutter_asteroids/ship.dart';
 import 'package:flutter_asteroids/vector.dart';
@@ -20,49 +21,71 @@ class MainApp extends StatefulWidget {
 }
 
 class _MainAppState extends State<MainApp> {
-  int score = 0;
+  final List<Asteroid> asteroids = <Asteroid>[];
 
-  final Ship ship = Ship(
-    size: size,
-    position: Vector(size.width / 2, size.height / 2),
-  );
+  late final Ship ship;
 
-  final List<Asteroid> asteroids = <Asteroid>[];
+  int score = 0;
+  bool isGameOver = false;
 
   @override
   void initState() {
     super.initState();
 
     _generateAstroids();
 
+    ship = Ship(
+      size: size,
+      position: Vector(size.width / 2, size.height / 2),
+      asteroids: asteroids,
+    );
+
     Timer.periodic(const Duration(milliseconds: 16), (_) {
-      ship.update();
+      if (!isGameOver) {
+        ship.update();
+      }
 
       for (final Asteroid asteroid in asteroids) {
         asteroid.update();
       }
 
+      _checkShipCollision();
+      _checkLaserCollision();
+
       setState(() {});
     });
   }
 
   @override
   Widget build(BuildContext context) => RawKeyboardListener(
         focusNode: FocusNode(),
-        onKey: _onKeyEventHandler,
+        onKey: isGameOver ? null : _onKeyEventHandler,
         child: MaterialApp(
           home: Scaffold(
             backgroundColor: Colors.black,
             body: Stack(
               children: <Widget>[
                 _buildScore(),
                 _buildPlayground(),
+                if (isGameOver) _buildGameOver(),
               ],
             ),
           ),
         ),
       );
 
+  Widget _buildGameOver() => Align(
+        child: Text(
+          'Game Over\nScore: $score\n🙁',
+          textAlign: TextAlign.center,
+          style: const TextStyle(
+            color: Colors.white,
+            fontSize: 54,
+            fontWeight: FontWeight.bold,
+          ),
+        ),
+      );
+
   Widget _buildScore() => Align(
         alignment: Alignment.topLeft,
         child: Padding(
@@ -81,12 +104,16 @@ class _MainAppState extends State<MainApp> {
   Widget _buildPlayground() => Center(
         child: CustomPaint(
           size: size,
-          painter: Playground(ship: ship, asteroids: asteroids),
+          painter: Playground(
+            ship: ship,
+            asteroids: asteroids,
+            gameOver: isGameOver,
+          ),
         ),
       );
 
   void _generateAstroids() {
-    for (int i = 0; i < 5; i++) {
+    for (int i = 0; i < 8; i++) {
       asteroids.add(
         Asteroid(
           size: size,
@@ -99,6 +126,57 @@ class _MainAppState extends State<MainApp> {
     }
   }
 
+  void _checkShipCollision() {
+    for (final Asteroid asteroid in asteroids) {
+      if (isColliding(
+        positionA: ship.position,
+        radiusA: ship.radius,
+        positionB: asteroid.position,
+        radiusB: asteroid.radius,
+      )) {
+        isGameOver = true;
+
+        break;
+      }
+    }
+  }
+
+  void _checkLaserCollision() {
+    for (int i = ship.lasers.length - 1; i >= 0; i--) {
+      for (final Asteroid asteroid in asteroids) {
+        if (isColliding(
+          positionA: ship.lasers[i].position,
+          radiusA: ship.lasers[i].radius,
+          positionB: asteroid.position,
+          radiusB: asteroid.radius,
+        )) {
+          score += 10;
+
+          ship.lasers.remove(ship.lasers[i]);
+
+          final double newRadius = asteroid.radius / 2;
+
+          if (newRadius > 5) {
+            for (int i = 0; i < 2; i++) {
+              asteroids.add(
+                Asteroid(
+                  size: size,
+                  position: asteroid.position,
+                  speed: asteroid.speed * 2,
+                  radius: newRadius,
+                ),
+              );
+            }
+          }
+
+          asteroids.remove(asteroid);
+
+          break;
+        }
+      }
+    }
+  }
+
   void _onKeyEventHandler(RawKeyEvent event) {
     switch (event.runtimeType) {
       case RawKeyDownEvent:

lib/playground.dart

@@ -6,12 +6,14 @@ class Playground extends CustomPainter {
   Playground({
     required this.ship,
     required this.asteroids,
+    required this.gameOver,
     this.drawDebug = false,
   });
 
-  final bool drawDebug;
   final Ship ship;
   final List<Asteroid> asteroids;
+  final bool gameOver;
+  final bool drawDebug;
 
   @override
   void paint(Canvas canvas, Size size) {
@@ -23,7 +25,11 @@ class Playground extends CustomPainter {
       asteroid.render(canvas);
     }
 
-    ship.render(canvas);
+    if (gameOver) {
+      ship.explode(canvas);
+    } else {
+      ship.render(canvas);
+    }
   }
 
   void _drawBorder(Canvas canvas, Size size) {

lib/ship.dart

@@ -1,6 +1,7 @@
 import 'dart:math';
 
 import 'package:flutter/material.dart';
+import 'package:flutter_asteroids/asteroid.dart';
 import 'package:flutter_asteroids/enums.dart';
 import 'package:flutter_asteroids/helpers.dart';
 import 'package:flutter_asteroids/laser.dart';
@@ -10,26 +11,29 @@ class Ship {
   Ship({
     required this.size,
     required this.position,
+    required this.asteroids,
     this.speed = 0.2,
     this.rotationSpeed = 0.1,
     this.drag = 0.98,
   });
 
-  final double radius = 10;
+  final List<Asteroid> asteroids;
 
   Size size;
   Vector position;
   double speed;
   double rotationSpeed;
   double drag;
 
+  final double radius = 10;
+  final List<Laser> lasers = <Laser>[];
+
   bool isTurningLeft = false;
   bool isTurningRight = false;
   bool isThrusting = false;
 
   double _rotation = 0;
   Vector _velocity = Vector.zero();
-  final List<Laser> _lasers = <Laser>[];
 
   void update() {
     if (isTurningLeft) {
@@ -64,7 +68,7 @@ class Ship {
     canvas.restore();
   }
 
-  void shoot() => _lasers.add(
+  void shoot() => lasers.add(
         Laser(
           size: size,
           position: position,
@@ -73,6 +77,25 @@ class Ship {
         ),
       );
 
+  void explode(Canvas canvas) {
+    final List<Color> colors = <Color>[
+      Colors.red,
+      Colors.orange,
+      Colors.yellow,
+    ];
+
+    final Paint paint = Paint()
+      ..strokeWidth = 2
+      ..color = colors[Random().nextInt(colors.length)]
+      ..style = PaintingStyle.fill;
+
+    canvas.drawCircle(
+      position.toOffset,
+      Random().nextDouble() * radius + radius,
+      paint,
+    );
+  }
+
   void _turn(Rotation rotation) =>
       _rotation += (rotation == Rotation.left ? -1 : 1) * rotationSpeed;
 
@@ -113,13 +136,13 @@ class Ship {
   }
 
   void _drawLaser(Canvas canvas) {
-    for (int i = 0; i < _lasers.length; i++) {
-      _lasers[i]
+    for (int i = 0; i < lasers.length; i++) {
+      lasers[i]
         ..render(canvas)
         ..update();
 
-      if (isOffScreen(_lasers[i].position, _lasers[i].radius, size)) {
-        _lasers.removeAt(i);
+      if (isOffScreen(lasers[i].position, lasers[i].radius, size)) {
+        lasers.removeAt(i);
       }
     }
   }

lib/vector.dart

@@ -21,6 +21,8 @@ class Vector {
 
   Vector operator +(Vector other) => Vector(x + other.x, y + other.y);
 
+  Vector operator -(Vector other) => Vector(x - other.x, y - other.y);
+
   Vector operator *(double scalar) => Vector(x * scalar, y * scalar);
 
   @override