flutter fireworks (gemini)

fireworks.dart

import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'dart:math';
import 'dart:async';
import 'dart:ui' as ui;
import 'dart:typed_data';

const bool kDebugMode = false;

const int kLaunchIntervalBaseMs = 400;
const int kLaunchIntervalRandomMs = 300;
const double kLaunchHorizontalPaddingFactor = 0.1;
const double kLaunchTargetHeightMinFactor = 0.05; // lower value
const double kLaunchTargetHeightMaxFactor = 0.1; // lower value

const double kRocketInitialVelocityYMin = 12.0;
const double kRocketInitialVelocityYRandom = 4.0;
const double kRocketInitialVelocityXMax = 0.2;
const double kRocketGravity = 0.16;
const double kRocketDamping = 0.99;
const double kRocketAcceleration = 0.015;
const int kRocketTrailMaxBaseLength = 10;
const int kRocketTrailBrushDensity = 1;
const double kRocketTrailSpread = 1.5;
const double kRocketTrailStrokeWidth = 0.8;
final Color kRocketTrailColor = Colors.orangeAccent.withValues(alpha: 0.4);

const int kBurstParticleCountBase = 500;
const int kBurstParticleCountRandom = 100;
const double kBurstParticleSpeedMin = 1.5;
const double kBurstParticleSpeedRandom = 5.5;
const double kBurstParticleSizeMin = 1.0;
const double kBurstParticleSizeRandom = 2.0;
const double kBurstParticleGravity = 0.15;
const double kBurstParticleDamping = 0.97;
const double kBurstParticleFadeRate = 0.95;
const double kBurstParticleInitialAlphaMin = 0.85;
const double kBurstParticleInitialAlphaRandom = 0.15;
const double kBurstStrokeWidth = 1.8;

const List<Color> kBurstColors = [
  Colors.red,
  Colors.redAccent,
  Colors.orangeAccent,
  Colors.yellowAccent,
  Colors.lightGreenAccent,
  Colors.lightBlueAccent,
  Colors.purpleAccent,
  Colors.pinkAccent,
  Colors.white,
  Colors.cyan,
];

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData.dark(),
      home: const FireworksDisplay(),
    );
  }
}

class FireworksDisplay extends StatefulWidget {
  const FireworksDisplay({Key? key}) : super(key: key);

  @override
  State<FireworksDisplay> createState() => _FireworksDisplayState();
}

class _FireworksDisplayState extends State<FireworksDisplay>
    with SingleTickerProviderStateMixin {
  late Ticker _ticker;
  Timer? _launchTimer;
  final Random _random = Random();
  Size _screenSize = Size.zero;

  List<Rocket> _rockets = [];
  List<BurstParticle> _burstParticles = [];

  Map<ui.Color, Float32List>? _groupedBurstPoints;
  Float32List? _trailPointsList;

  @override
  void initState() {
    super.initState();
    _ticker = createTicker(_updateAnimation)..start();
    _startLaunchTimer();

    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) {
        Future.delayed(const Duration(milliseconds: 50), () {
          if (mounted) {
            setState(() {
              _screenSize = MediaQuery.sizeOf(context);
            });
          }
        });
      }
    });
  }

  void _startLaunchTimer() {
    _launchTimer?.cancel();
    _launchTimer = Timer.periodic(
      Duration(
        milliseconds:
            kLaunchIntervalBaseMs +
            _random.nextInt(kLaunchIntervalRandomMs + 1),
      ),
      (timer) {
        if (mounted && _screenSize != Size.zero) {
          _launchFirework();
        }
      },
    );
  }

  void _updateAnimation(Duration elapsed) {
    if (!mounted) return;

    final List<Map<String, dynamic>> burstsToSpawn = [];

    _rockets.removeWhere((rocket) {
      rocket.update();
      if (rocket.hasReachedApex()) {
        burstsToSpawn.add({
          'position': rocket.position,
          'color': rocket.burstColor,
        });
        return true;
      }
      return false;
    });

    for (var burstData in burstsToSpawn) {
      _spawnBurst(burstData['position'], burstData['color']);
    }

    _burstParticles.removeWhere((particle) {
      particle.update();
      return particle.isDead();
    });

    _prepareRenderData();

    setState(() {});
  }

  void _launchFirework() {
    if (_screenSize == Size.zero) return;

    final double horizontalPadding =
        _screenSize.width * kLaunchHorizontalPaddingFactor;
    final launchX =
        horizontalPadding +
        _random.nextDouble() * (_screenSize.width - 2 * horizontalPadding);
    final launchPosition = Offset(launchX, _screenSize.height + 10);

    final minHeight = _screenSize.height * kLaunchTargetHeightMinFactor;
    final maxHeight = _screenSize.height * kLaunchTargetHeightMaxFactor;
    final targetHeight =
        minHeight + _random.nextDouble() * (maxHeight - minHeight);

    final Color selectedBurstColor =
        kBurstColors[_random.nextInt(kBurstColors.length)];

    _rockets.add(
      Rocket(
        startPosition: launchPosition,
        targetHeight: targetHeight,
        burstColor: selectedBurstColor,
        random: _random,
      ),
    );
  }

  void _spawnBurst(Offset position, Color burstColor) {
    int numberOfParticles =
        kBurstParticleCountBase +
        _random.nextInt(kBurstParticleCountRandom + 1);

    for (int i = 0; i < numberOfParticles; i++) {
      final angle = _random.nextDouble() * 2 * pi;
      final speed =
          kBurstParticleSpeedMin +
          _random.nextDouble() * kBurstParticleSpeedRandom;
      final size =
          kBurstParticleSizeMin +
          _random.nextDouble() * kBurstParticleSizeRandom;

      _burstParticles.add(
        BurstParticle(
          position: position,
          angle: angle,
          speed: speed,
          random: _random,
          color: burstColor,
          size: size,
        ),
      );
    }
  }

  void _prepareRenderData() {
    final Map<ui.Color, List<Offset>> pointsByColor = {};
    for (final particle in _burstParticles) {
      (pointsByColor[particle.color] ??= []).add(particle.position);
    }

    if (pointsByColor.isNotEmpty) {
      _groupedBurstPoints = {};
      pointsByColor.forEach((color, offsets) {
        if (offsets.isNotEmpty) {
          final pointsList = Float32List(offsets.length * 2);
          for (int i = 0; i < offsets.length; i++) {
            pointsList[i * 2] = offsets[i].dx;
            pointsList[i * 2 + 1] = offsets[i].dy;
          }
          _groupedBurstPoints![color] = pointsList;
        }
      });
      _groupedBurstPoints!.removeWhere((key, value) => value.isEmpty);
      if (_groupedBurstPoints!.isEmpty) _groupedBurstPoints = null;
    } else {
      _groupedBurstPoints = null;
    }

    List<Offset> allTrailPoints = [];
    for (final rocket in _rockets) {
      allTrailPoints.addAll(rocket.trail);
    }

    if (allTrailPoints.isNotEmpty) {
      _trailPointsList = Float32List(allTrailPoints.length * 2);
      for (int i = 0; i < allTrailPoints.length; i++) {
        _trailPointsList![i * 2] = allTrailPoints[i].dx;
        _trailPointsList![i * 2 + 1] = allTrailPoints[i].dy;
      }
    } else {
      _trailPointsList = null;
    }
  }

  @override
  void dispose() {
    _ticker.dispose();
    _launchTimer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final currentSize = MediaQuery.sizeOf(context);
    if (_screenSize != currentSize && currentSize != Size.zero) {
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (mounted) {
          setState(() {
            _screenSize = currentSize;
          });
        }
      });
    }

    return Material(
      color: Colors.transparent,
      child: CustomPaint(
        size: Size.infinite,
        painter: _FireworksPainter(
          groupedBurstPoints: _groupedBurstPoints,
          trailPoints: _trailPointsList,
        ),
      ),
    );
  }
}

class Rocket {
  Offset position;
  final double targetHeight;
  final Color burstColor;
  final Random random;
  List<Offset> trail = [];
  Offset velocity;

  Rocket({
    required Offset startPosition,
    required this.targetHeight,
    required this.burstColor,
    required this.random,
  }) : position = startPosition,
       velocity = Offset(
         (random.nextDouble() - 0.5) * (kRocketInitialVelocityXMax * 2),
         -(kRocketInitialVelocityYMin +
             random.nextDouble() * kRocketInitialVelocityYRandom),
       );

  void update() {
    trail.insert(0, position);
    if (kRocketTrailBrushDensity > 0) {
      for (int i = 0; i < kRocketTrailBrushDensity; i++) {
        double offsetX = (random.nextDouble() - 0.5) * kRocketTrailSpread * 2;
        double offsetY = (random.nextDouble() - 0.5) * kRocketTrailSpread * 0.5;
        trail.insert(0, position + Offset(offsetX, offsetY));
        trail.insert(0, position + Offset(-offsetX, -offsetY));
      }
    }

    int dynamicMaxLength =
        (kRocketTrailMaxBaseLength * (1 + kRocketTrailBrushDensity * 2));
    while (trail.length > dynamicMaxLength) {
      trail.removeLast();
    }

    velocity = Offset(
      velocity.dx * kRocketDamping,
      (velocity.dy - kRocketAcceleration + kRocketGravity) * kRocketDamping,
    );

    position += velocity;
  }

  bool hasReachedApex() {
    return velocity.dy >= -0.1 || position.dy <= targetHeight;
  }
}

class BurstParticle {
  Offset position;
  Color color;

  late double _vx;
  late double _vy;
  double _alpha;

  BurstParticle({
    required this.position,
    required double angle,
    required double speed,
    required Random random,
    required this.color,
    required double size,
  }) : _alpha =
           kBurstParticleInitialAlphaMin +
           random.nextDouble() * kBurstParticleInitialAlphaRandom {
    _vx = speed * cos(angle);
    _vy = speed * sin(angle);
  }

  void update() {
    _vy += kBurstParticleGravity;
    _vx *= kBurstParticleDamping;
    _vy *= kBurstParticleDamping;

    position = Offset(position.dx + _vx, position.dy + _vy);

    _alpha *= kBurstParticleFadeRate;
    if (_alpha < 0.01) _alpha = 0;

    color = color.withValues(alpha: _alpha);
  }

  bool isDead() {
    return _alpha <= 0.01;
  }
}

class _FireworksPainter extends CustomPainter {
  final Map<ui.Color, Float32List>? groupedBurstPoints;
  final Float32List? trailPoints;

  final Paint _burstPaint =
      Paint()
        ..strokeWidth = kBurstStrokeWidth
        ..strokeCap = ui.StrokeCap.round;

  final Paint _trailPaint =
      Paint()
        ..strokeWidth = kRocketTrailStrokeWidth
        ..color = kRocketTrailColor
        ..strokeCap = ui.StrokeCap.round;

  _FireworksPainter({
    required this.groupedBurstPoints,
    required this.trailPoints,
  });

  @override
  void paint(Canvas canvas, Size size) {
    if (trailPoints != null && trailPoints!.isNotEmpty) {
      canvas.drawRawPoints(ui.PointMode.points, trailPoints!, _trailPaint);
    }

    if (groupedBurstPoints != null && groupedBurstPoints!.isNotEmpty) {
      groupedBurstPoints!.forEach((color, points) {
        _burstPaint.color = color;
        canvas.drawRawPoints(ui.PointMode.points, points, _burstPaint);
      });
    }
  }

  @override
  bool shouldRepaint(_FireworksPainter oldDelegate) {
    return oldDelegate.groupedBurstPoints != groupedBurstPoints ||
        oldDelegate.trailPoints != trailPoints;
  }
}

extension ColorAlpha on Color {
  Color withValues({double? alpha, int? r, int? g, int? b}) {
    return Color.fromARGB(
      ((alpha ?? this.a / 255.0) * 255).clamp(0, 255).toInt(),
      r ?? this.r.toInt(),
      g ?? this.g.toInt(),
      b ?? this.b.toInt(),
    );
  }
}