shader_home_page.dart

class ShaderHomePage extends StatefulWidget {
  const ShaderHomePage({super.key});

  @override
  State<ShaderHomePage> createState() => _ShaderHomePageState();
}

class _ShaderHomePageState extends State<ShaderHomePage> {
  late Timer timer;
  double delta = 0;
  FragmentShader? shader;

  void loadMyShader() async {
    var program = await FragmentProgram.fromAsset('shaders/shader.frag');
    shader = program.fragmentShader();
    setState(() {
      // trigger a repaint
    });

    timer = Timer.periodic(const Duration(milliseconds: 16), (timer) {
      setState(() {
        delta += 1 / 60;
      });
    });
  }

  @override
  void initState() {
    super.initState();
    loadMyShader();
  }

  @override
  void dispose() {
    timer.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (shader == null) {
      return const Center(child: CircularProgressIndicator());
    } else {
      return CustomPaint(painter: ShaderPainter(shader!, delta));
    }
  }
}