Alien UFO - Custom Animations

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
      body: MyHomePage(),
    ));
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _animation;

  final Image starsBackground = Image.network(
    'https://images.unsplash.com/photo-1531742896094-1424584e750b?q=80&w=1888&auto=format&fit=crop&ixlib=rb-4.0.3&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D',
    fit: BoxFit.cover,
  );
  final Image ufo = Image.network(
    'https://img.icons8.com/?size=100&id=YxY4BUR02xKl&format=png&color=000000',
    width: 100,
    height: 100,
  );

  final Image cow = Image.network(
    'https://img.icons8.com/?size=100&id=9IHYMlaJkuiP&format=png&color=000000',
    width: 80,
    height: 80,
  );

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 5),
      vsync: this,
    )..repeat(reverse: true);

    _animation = CurvedAnimation(
      parent: _controller,
      curve: Curves.easeInOut,
    );
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        alignment: AlignmentDirectional.center,
        children: <Widget>[
          Positioned(
            top: 0,
            left: 0,
            right: 0,
            bottom: 0,
            child: starsBackground,
          ),
          AnimatedBuilder(
            animation: _animation,
            builder: (context, child) {
              return Positioned(
                top: (_animation.value * 200) - 800,
                child: ClipPath(
                  clipper: BeamClipper(_animation.value),
                  child: Container(
                    height: 2000,
                    width: 900,
                    decoration: BoxDecoration(
                      gradient: RadialGradient(
                        radius: 2.0,
                        colors: [
                          Colors.yellow.withOpacity(1.0 - _animation.value),
                          Colors.transparent,
                        ],
                      ),
                    ),
                  ),
                ),
              );
            },
          ),
          AnimatedBuilder(
            animation: _animation,
            builder: (context, child) {
              return Positioned(
                top: 100 + (_animation.value * 200),
                child: ufo,
              );
            },
          ),
          AnimatedBuilder(
            animation: _animation,
            builder: (context, child) {
              return Positioned(
                bottom: 30 + (_animation.value * 200),
                child: Opacity(
                  opacity: 1.0 - _animation.value,
                  child: cow,
                ),
              );
            },
          ),
        ],
      ),
    );
  }
}

class BeamClipper extends CustomClipper<Path> {
  final double animationValue;

  BeamClipper(this.animationValue);

  @override
  Path getClip(Size size) {
    return Path()
      ..moveTo(size.width / 2, size.height / 2)
      ..lineTo(size.width / 2 + (animationValue * size.width / 2), size.height)
      ..lineTo(size.width / 2 - (animationValue * size.width / 2), size.height)
      ..close();
  }

  @override
  bool shouldReclip(CustomClipper oldClipper) => true;
}