refactor: continual refactor to support multiple render targets

thermion_dart/lib/src/utils/gizmo.dart

@@ -0,0 +1,127 @@
+import 'dart:async';
+
+import 'package:thermion_dart/src/viewer/viewer.dart';
+import 'package:vector_math/vector_math_64.dart';
+
+abstract class Gizmo {
+  bool get isVisible;
+  bool get isHovered;
+
+  void reset();
+
+  Future attach(ThermionEntity entity);
+  Future detach();
+
+  Stream<Aabb2> get boundingBox;
+
+  void checkHover(int x, int y);
+}
+
+abstract class BaseGizmo extends Gizmo {
+  final ThermionEntity x;
+  final ThermionEntity y;
+  final ThermionEntity z;
+  final ThermionEntity center;
+
+  ThermionEntity? _activeAxis;
+  ThermionEntity? _activeEntity;
+  ThermionViewer viewer;
+
+  bool _visible = false;
+  bool get isVisible => _visible;
+
+  bool _isHovered = false;
+  bool get isHovered => _isHovered;
+
+  final Set<ThermionEntity> ignore;
+
+  Stream<Aabb2> get boundingBox => _boundingBoxController.stream;
+  final _boundingBoxController = StreamController<Aabb2>.broadcast();
+
+  BaseGizmo({required this.x, required this.y, required this.z, required this.center, required this.viewer,
+      this.ignore = const <ThermionEntity>{}}) {
+    onPick(_onGizmoPickResult);
+  }
+
+  final _stopwatch = Stopwatch();
+
+  double _transX = 0.0;
+  double _transY = 0.0;
+
+  Future translate(double transX, double transY) async {
+    if (!_stopwatch.isRunning) {
+      _stopwatch.start();
+    }
+
+    _transX += transX;
+    _transY += transY;
+
+    if (_stopwatch.elapsedMilliseconds < 16) {
+      return;
+    }
+
+    final axis = Vector3(_activeAxis == x ? 1.0 : 0.0,
+        _activeAxis == y ? 1.0 : 0.0, _activeAxis == z ? 1.0 : 0.0);
+
+    await viewer.queueRelativePositionUpdateWorldAxis(
+        _activeEntity!,
+        _transX,
+        -_transY, // flip the sign because "up" in NDC Y axis is positive, but negative in Flutter
+        axis.x,
+        axis.y,
+        axis.z);
+    _transX = 0;
+    _transY = 0;
+    _stopwatch.reset();
+  }
+
+  void reset() {
+    _activeAxis = null;
+  }
+
+  void _onGizmoPickResult(FilamentPickResult result) async {
+    if (result.entity == x || result.entity == y || result.entity == z) {
+      _activeAxis = result.entity;
+      _isHovered = true;
+    } else if (result.entity == 0) {
+      _activeAxis = null;
+      _isHovered = false;
+    } else {
+      throw Exception("Unexpected gizmo pick result");
+    }
+  }
+
+  Future attach(ThermionEntity entity) async {
+    _activeAxis = null;
+    if (entity == _activeEntity) {
+      return;
+    }
+    if (entity == center) {
+      _activeEntity = null;
+      return;
+    }
+    _visible = true;
+
+    if (_activeEntity != null) {
+      await viewer.removeStencilHighlight(_activeEntity!);
+    }
+    _activeEntity = entity;
+
+    await viewer.setParent(center, entity, preserveScaling: false);
+    _boundingBoxController.sink.add(await viewer.getViewportBoundingBox(x));
+  }
+
+  Future detach() async {
+    await setVisibility(false);
+  }
+
+  @override
+  void checkHover(int x, int y) {
+    pick(x, y);
+  }
+
+  Future pick(int x, int y);
+
+  Future setVisibility(bool visible);
+  void onPick(void Function(PickResult result) callback);
+}