3D spinny ball - by Simon Lightfoot :: #HumpdayQandA on 7th May 2025 :: https://www.youtube.com/watch?v=CqmhwUnesvQ

humpday_2025-05-04_1.dart

// MIT License
//
// Copyright (c) 2025 Simon Lightfoot
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import 'dart:math' as math;
import 'dart:ui' as ui;

import 'package:flutter/material.dart';
import 'package:vector_math/vector_math_64.dart' show Vector3;

void main() {
  runApp(
    MaterialApp(
      home: AiExample(),
    ),
  );
}

@immutable
class AiExample extends StatefulWidget {
  const AiExample({super.key});

  @override
  State<AiExample> createState() => _AiExampleState();
}

class _AiExampleState extends State<AiExample> with SingleTickerProviderStateMixin {
  late AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(milliseconds: 10000),
      vsync: this,
    );
    _controller.repeat();
  }

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

  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(
        child: CustomPaint(
          painter: AiPainter(_controller),
          size: Size(300.0, 300.0),
        ),
      ),
    );
  }
}

class AiPainter extends CustomPainter {
  AiPainter(this.animation) : super(repaint: animation);

  final Animation<double> animation;

  @override
  void paint(Canvas canvas, Size size) {
    final rect = Offset.zero & size;
    //canvas.drawRect(rect, Paint()..color = Colors.red);

    canvas.save();
    canvas.translate(size.width / 2, size.height / 2);

    final matrix = Matrix4.identity()
      //..setEntry(3, 2, 0.002)
      ..rotateX(math.pi * 0.2)
      ..rotateX(math.pi * 2 * animation.value)
      ..rotateY(math.pi * 2 * animation.value);

    final radius = size.shortestSide / 2 - 10.0;

    final gradient = ui.Gradient.radial(
      Offset.fromDirection(360 * (math.pi / 180) * animation.value, radius * 0.8),
      radius,
      [Colors.blueAccent, Colors.purpleAccent],
    );
    canvas.drawCircle(
      Offset.zero,
      radius,
      Paint()
        ..shader = gradient
        ..maskFilter = ui.MaskFilter.blur(
          ui.BlurStyle.normal,
          ui.Shadow.convertRadiusToSigma(10.0),
        ),
    );

    final paint = Paint()..color = Colors.white;
    for (var inclination = 0.0; inclination < 360.0; inclination += 10) {
      for (var azimuth = 0.0; azimuth < 180.0; azimuth += 10) {
        final phi = inclination * (math.pi / 180);
        final theta = azimuth * (math.pi / 180);
        final v3 = Vector3(
          radius * math.sin(phi) * math.cos(theta),
          radius * math.sin(phi) * math.sin(theta),
          radius * math.cos(phi),
        );
        final v32 = matrix.perspectiveTransform(v3);
        final offset = Offset(v32.x, v32.y);
        final cr = (3.0 * v32.z) / radius;
        if (cr >= 0.5) {
          canvas.drawCircle(offset, (3.0 * v32.z) / radius, paint);
        }
      }
    }

    canvas.restore();
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return true;
  }
}