实现伪3d球面

lib/components/sphere_cloud.dart

@@ -0,0 +1,164 @@
+import 'dart:math' as math;
+import 'package:flutter/material.dart';
+
+class SphereCloud extends StatefulWidget {
+  const SphereCloud({
+    super.key,
+    required this.items,
+    this.radius = 140,
+    this.itemSize = 48,
+    this.cameraZ = 400, // 相机离球心距离，越大透视越弱
+    this.focal = 240,   // 焦距，影响投影与缩放
+    this.minScale = 0.45,
+    this.maxScale = 1.25,
+  });
+
+  final List<Widget> items;
+  final double radius;
+  final double itemSize;
+  final double cameraZ;
+  final double focal;
+  final double minScale;
+  final double maxScale;
+
+  @override
+  State<SphereCloud> createState() => _SphereCloudState();
+}
+
+class _SphereCloudState extends State<SphereCloud> {
+  late final List<_Point3> _points;
+
+  // 当前旋转角（弧度）
+  double _rotX = 0.0;
+  double _rotY = 0.0;
+
+  @override
+  void initState() {
+    super.initState();
+    _points = _genFibonacciSphere(widget.items.length, widget.radius);
+  }
+
+  @override
+  void didUpdateWidget(covariant SphereCloud oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.items.length != widget.items.length ||
+        oldWidget.radius != widget.radius) {
+      _points
+        ..clear()
+        ..addAll(_genFibonacciSphere(widget.items.length, widget.radius));
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return LayoutBuilder(builder: (_, c) {
+      final cx = c.maxWidth / 2;
+      final cy = c.maxHeight / 2;
+
+      // 计算每个点投影后的 2D 信息
+      final projected = <_ProjectedItem>[];
+      for (int i = 0; i < _points.length; i++) {
+        final p = _rotate(_points[i], _rotX, _rotY);
+
+        // 透视：避免 cameraZ - z 过小导致爆炸
+        final denom = (widget.cameraZ - p.z).clamp(40.0, 1e9);
+        final perspective = widget.focal / denom;
+
+        final x2 = cx + p.x * perspective;
+        final y2 = cy + p.y * perspective;
+
+        final scale = perspective.clamp(widget.minScale, widget.maxScale);
+
+        projected.add(_ProjectedItem(
+          index: i,
+          x: x2,
+          y: y2,
+          z: p.z,
+          scale: scale,
+        ));
+      }
+
+      // 按 z 排序：远->近
+      projected.sort((a, b) => a.z.compareTo(b.z));
+
+      return GestureDetector(
+        onPanUpdate: (d) {
+          // 你可以按手感调整系数
+          setState(() {
+            _rotY += d.delta.dx * 0.01;
+            _rotX -= d.delta.dy * 0.01;
+          });
+        },
+        child: Stack(
+          clipBehavior: Clip.none,
+          children: [
+            for (final it in projected)
+              Positioned(
+                left: it.x - widget.itemSize / 2,
+                top: it.y - widget.itemSize / 2,
+                child: Transform.scale(
+                  scale: it.scale,
+                  child: SizedBox(
+                    width: widget.itemSize,
+                    height: widget.itemSize,
+                    child: widget.items[it.index],
+                  ),
+                ),
+              ),
+          ],
+        ),
+      );
+    });
+  }
+
+  // Fibonacci sphere：简单、分布均匀（比随机更像“均匀铺满球面”）
+  List<_Point3> _genFibonacciSphere(int n, double r) {
+    if (n <= 0) return [];
+    final pts = <_Point3>[];
+    final offset = 2.0 / n;
+    final increment = math.pi * (3.0 - math.sqrt(5.0)); // golden angle
+    for (int i = 0; i < n; i++) {
+      final y = ((i * offset) - 1) + (offset / 2);
+      final rr = math.sqrt(1 - y * y);
+      final phi = i * increment;
+      final x = math.cos(phi) * rr;
+      final z = math.sin(phi) * rr;
+      pts.add(_Point3(x * r, y * r, z * r));
+    }
+    return pts;
+  }
+
+  // 绕 X/Y 旋转（右手系）
+  _Point3 _rotate(_Point3 p, double rx, double ry) {
+    // rotate around X
+    final cosX = math.cos(rx), sinX = math.sin(rx);
+    var y1 = p.y * cosX - p.z * sinX;
+    var z1 = p.y * sinX + p.z * cosX;
+
+    // rotate around Y
+    final cosY = math.cos(ry), sinY = math.sin(ry);
+    var x2 = p.x * cosY + z1 * sinY;
+    var z2 = -p.x * sinY + z1 * cosY;
+
+    return _Point3(x2, y1, z2);
+  }
+}
+
+class _Point3 {
+  _Point3(this.x, this.y, this.z);
+  final double x, y, z;
+}
+
+class _ProjectedItem {
+  _ProjectedItem({
+    required this.index,
+    required this.x,
+    required this.y,
+    required this.z,
+    required this.scale,
+  });
+
+  final int index;
+  final double x, y, z;
+  final double scale;
+}