feat(viewport): orbit drag/zoom controls with idle auto-rotate pause; cache-busted script urls

6 files changed, 1516 insertions, 17 deletions

diff --git a/public/App.js b/public/App.js
index c98b708..1f28482 100644
--- a/public/App.js
+++ b/public/App.js
@@ -1,7 +1,7 @@
 import { Union, Record } from "./fable_modules/fable-library-js.4.24.0/Types.js";
-import { union_type, class_type, record_type, bool_type, string_type } from "./fable_modules/fable-library-js.4.24.0/Reflection.js";
-import { Replay_frames } from "./SomhairlesDream.Shared/Replay.js";
+import { union_type, obj_type, class_type, record_type, bool_type, string_type } from "./fable_modules/fable-library-js.4.24.0/Reflection.js";
 import { comparePrimitives, defaultOf, equals, createAtom } from "./fable_modules/fable-library-js.4.24.0/Util.js";
+import { Replay_frames } from "./SomhairlesDream.Shared/Replay.js";
 import { sortBy, map, equalsWith, tryFind, iterateIndexed, item } from "./fable_modules/fable-library-js.4.24.0/Array.js";
 import { join, isNullOrWhiteSpace, printf, toText } from "./fable_modules/fable-library-js.4.24.0/String.js";
 import { MeshData_triangleIndices, MeshData_positionData } from "./SomhairlesDream.Shared/Domain.js";
@@ -26,20 +26,25 @@ export function RunSelection_$reflection() {
 }
 
 export class ViewState extends Record {
-    constructor(Renderer, Scene, Camera, Group, Canvas) {
+    constructor(Renderer, Scene, Camera, Group, Canvas, Controls) {
         super();
         this.Renderer = Renderer;
         this.Scene = Scene;
         this.Camera = Camera;
         this.Group = Group;
         this.Canvas = Canvas;
+        this.Controls = Controls;
     }
 }
 
 export function ViewState_$reflection() {
-    return record_type("SomhairlesDream.Frontend.App.ViewState", [], ViewState, () => [["Renderer", string_type], ["Scene", string_type], ["Camera", string_type], ["Group", string_type], ["Canvas", class_type("Browser.Types.HTMLCanvasElement", undefined)]]);
+    return record_type("SomhairlesDream.Frontend.App.ViewState", [], ViewState, () => [["Renderer", string_type], ["Scene", string_type], ["Camera", string_type], ["Group", string_type], ["Canvas", class_type("Browser.Types.HTMLCanvasElement", undefined)], ["Controls", obj_type]]);
 }
 
+export let lastInteractionMs = createAtom(0);
+
+export const idleSpinDelayMs = 3500;
+
 export class LoadOwner extends Record {
     constructor(ProjectId, RunId, Path) {
         super();
@@ -263,6 +268,14 @@ export function frameObject(view, node) {
             camera.far = (distance + (radius * 4));
             camera.lookAt(0, 0, 0);
             camera.updateProjectionMatrix();
+            const matchValue_3 = view.Controls;
+            if (equals(matchValue_3, defaultOf())) {
+            }
+            else {
+                const controls = matchValue_3;
+                controls.target.copy({ x: 0, y: 0, z: 0 });
+                controls.update();
+            }
         }
     }
 }
@@ -297,25 +310,42 @@ export function initializeView() {
     scene.background = (new THREE.Color("#11171a"));
     const camera = new THREE.PerspectiveCamera(34, (width / height), 0.1, 100);
     camera.position.set(6.4, 4.6, 7.2);
-    camera.lookAt(0, 1.2, 0);
+    camera.lookAt(0, 0, 0);
     const group = new THREE.Group();
     scene.add(group);
     scene.add(new THREE.AmbientLight("#f0e6c8", 1.9));
     const keyLight = new THREE.DirectionalLight("#f2c76b", 2.8);
     keyLight.position.set(4, 7, 5);
     scene.add(keyLight);
-    const view = new ViewState(renderer, scene, camera, group, canvas);
+    const controls = new OrbitControls(camera, canvas);
+    controls.target.copy({ x: 0, y: 0, z: 0 });
+    controls.enableDamping = true;
+    controls.autoRotateSpeed = 0.7;
+    const view = new ViewState(renderer, scene, camera, group, canvas, controls);
     viewState(view);
     freezeRotation((new URLSearchParams(window.location.search).get("freeze")) === "1");
-    window.SOMHAIRLES_VIEWER = { camera: camera, scene: scene, group: group, canvas: canvas };
+    controls.autoRotate = !freezeRotation();
+    window.SOMHAIRLES_VIEWER = { camera: camera, scene: scene, group: group, canvas: canvas, controls: controls };
     renderFrame(selectedFrame());
     window.addEventListener("resize", (_arg) => {
         resizeView(view);
     });
-    const animate = (_arg_1) => {
+    canvas.addEventListener("pointerdown", (_arg_1) => {
+        lastInteractionMs(Date.now());
+    });
+    canvas.addEventListener("wheel", (_arg_2) => {
+        lastInteractionMs(Date.now());
+    });
+    canvas.addEventListener("touchstart", (_arg_3) => {
+        lastInteractionMs(Date.now());
+    });
+    const animate = (nowMs) => {
+        controls.update();
         if (!freezeRotation()) {
             group.rotation.y = (group.rotation.y + 0.003);
         }
+        const interacting = (nowMs - lastInteractionMs()) < idleSpinDelayMs;
+        controls.autoRotate = (!freezeRotation() && !interacting);
         renderer.render(scene, camera);
         requestAnimationFrame(animate);
     };
diff --git a/public/index.html b/public/index.html
index d6966b1..494d26c 100644
--- a/public/index.html
+++ b/public/index.html
@@ -14,7 +14,7 @@
       }
     }
   </script>
-  <script type="module" src="/vendor/three-setup.js"></script>
+  <script type="module" src="/vendor/three-setup.js?v=orbit1"></script>
 </head>
 <body>
   <main class="shell" aria-labelledby="page-title">
@@ -196,6 +196,6 @@
       <span>heritage 参考线保留占位演示 · F# / OPEN CODE</span>
     </footer>
   </main>
-  <script type="module" src="/App.js"></script>
+  <script type="module" src="/App.js?v=orbit1"></script>
 </body>
 </html>
diff --git a/public/vendor/addons/controls/OrbitControls.js b/public/vendor/addons/controls/OrbitControls.js
new file mode 100644
index 0000000..f29e7fe
--- /dev/null
+++ b/public/vendor/addons/controls/OrbitControls.js
@@ -0,0 +1,1417 @@
+import {
+	EventDispatcher,
+	MOUSE,
+	Quaternion,
+	Spherical,
+	TOUCH,
+	Vector2,
+	Vector3,
+	Plane,
+	Ray,
+	MathUtils
+} from 'three';
+
+// OrbitControls performs orbiting, dollying (zooming), and panning.
+// Unlike TrackballControls, it maintains the "up" direction object.up (+Y by default).
+//
+//    Orbit - left mouse / touch: one-finger move
+//    Zoom - middle mouse, or mousewheel / touch: two-finger spread or squish
+//    Pan - right mouse, or left mouse + ctrl/meta/shiftKey, or arrow keys / touch: two-finger move
+
+const _changeEvent = { type: 'change' };
+const _startEvent = { type: 'start' };
+const _endEvent = { type: 'end' };
+const _ray = new Ray();
+const _plane = new Plane();
+const TILT_LIMIT = Math.cos( 70 * MathUtils.DEG2RAD );
+
+class OrbitControls extends EventDispatcher {
+
+	constructor( object, domElement ) {
+
+		super();
+
+		this.object = object;
+		this.domElement = domElement;
+		this.domElement.style.touchAction = 'none'; // disable touch scroll
+
+		// Set to false to disable this control
+		this.enabled = true;
+
+		// "target" sets the location of focus, where the object orbits around
+		this.target = new Vector3();
+
+		// Sets the 3D cursor (similar to Blender), from which the maxTargetRadius takes effect
+		this.cursor = new Vector3();
+
+		// How far you can dolly in and out ( PerspectiveCamera only )
+		this.minDistance = 0;
+		this.maxDistance = Infinity;
+
+		// How far you can zoom in and out ( OrthographicCamera only )
+		this.minZoom = 0;
+		this.maxZoom = Infinity;
+
+		// Limit camera target within a spherical area around the cursor
+		this.minTargetRadius = 0;
+		this.maxTargetRadius = Infinity;
+
+		// How far you can orbit vertically, upper and lower limits.
+		// Range is 0 to Math.PI radians.
+		this.minPolarAngle = 0; // radians
+		this.maxPolarAngle = Math.PI; // radians
+
+		// How far you can orbit horizontally, upper and lower limits.
+		// If set, the interval [ min, max ] must be a sub-interval of [ - 2 PI, 2 PI ], with ( max - min < 2 PI )
+		this.minAzimuthAngle = - Infinity; // radians
+		this.maxAzimuthAngle = Infinity; // radians
+
+		// Set to true to enable damping (inertia)
+		// If damping is enabled, you must call controls.update() in your animation loop
+		this.enableDamping = false;
+		this.dampingFactor = 0.05;
+
+		// This option actually enables dollying in and out; left as "zoom" for backwards compatibility.
+		// Set to false to disable zooming
+		this.enableZoom = true;
+		this.zoomSpeed = 1.0;
+
+		// Set to false to disable rotating
+		this.enableRotate = true;
+		this.rotateSpeed = 1.0;
+
+		// Set to false to disable panning
+		this.enablePan = true;
+		this.panSpeed = 1.0;
+		this.screenSpacePanning = true; // if false, pan orthogonal to world-space direction camera.up
+		this.keyPanSpeed = 7.0;	// pixels moved per arrow key push
+		this.zoomToCursor = false;
+
+		// Set to true to automatically rotate around the target
+		// If auto-rotate is enabled, you must call controls.update() in your animation loop
+		this.autoRotate = false;
+		this.autoRotateSpeed = 2.0; // 30 seconds per orbit when fps is 60
+
+		// The four arrow keys
+		this.keys = { LEFT: 'ArrowLeft', UP: 'ArrowUp', RIGHT: 'ArrowRight', BOTTOM: 'ArrowDown' };
+
+		// Mouse buttons
+		this.mouseButtons = { LEFT: MOUSE.ROTATE, MIDDLE: MOUSE.DOLLY, RIGHT: MOUSE.PAN };
+
+		// Touch fingers
+		this.touches = { ONE: TOUCH.ROTATE, TWO: TOUCH.DOLLY_PAN };
+
+		// for reset
+		this.target0 = this.target.clone();
+		this.position0 = this.object.position.clone();
+		this.zoom0 = this.object.zoom;
+
+		// the target DOM element for key events
+		this._domElementKeyEvents = null;
+
+		//
+		// public methods
+		//
+
+		this.getPolarAngle = function () {
+
+			return spherical.phi;
+
+		};
+
+		this.getAzimuthalAngle = function () {
+
+			return spherical.theta;
+
+		};
+
+		this.getDistance = function () {
+
+			return this.object.position.distanceTo( this.target );
+
+		};
+
+		this.listenToKeyEvents = function ( domElement ) {
+
+			domElement.addEventListener( 'keydown', onKeyDown );
+			this._domElementKeyEvents = domElement;
+
+		};
+
+		this.stopListenToKeyEvents = function () {
+
+			this._domElementKeyEvents.removeEventListener( 'keydown', onKeyDown );
+			this._domElementKeyEvents = null;
+
+		};
+
+		this.saveState = function () {
+
+			scope.target0.copy( scope.target );
+			scope.position0.copy( scope.object.position );
+			scope.zoom0 = scope.object.zoom;
+
+		};
+
+		this.reset = function () {
+
+			scope.target.copy( scope.target0 );
+			scope.object.position.copy( scope.position0 );
+			scope.object.zoom = scope.zoom0;
+
+			scope.object.updateProjectionMatrix();
+			scope.dispatchEvent( _changeEvent );
+
+			scope.update();
+
+			state = STATE.NONE;
+
+		};
+
+		// this method is exposed, but perhaps it would be better if we can make it private...
+		this.update = function () {
+
+			const offset = new Vector3();
+
+			// so camera.up is the orbit axis
+			const quat = new Quaternion().setFromUnitVectors( object.up, new Vector3( 0, 1, 0 ) );
+			const quatInverse = quat.clone().invert();
+
+			const lastPosition = new Vector3();
+			const lastQuaternion = new Quaternion();
+			const lastTargetPosition = new Vector3();
+
+			const twoPI = 2 * Math.PI;
+
+			return function update( deltaTime = null ) {
+
+				const position = scope.object.position;
+
+				offset.copy( position ).sub( scope.target );
+
+				// rotate offset to "y-axis-is-up" space
+				offset.applyQuaternion( quat );
+
+				// angle from z-axis around y-axis
+				spherical.setFromVector3( offset );
+
+				if ( scope.autoRotate && state === STATE.NONE ) {
+
+					rotateLeft( getAutoRotationAngle( deltaTime ) );
+
+				}
+
+				if ( scope.enableDamping ) {
+
+					spherical.theta += sphericalDelta.theta * scope.dampingFactor;
+					spherical.phi += sphericalDelta.phi * scope.dampingFactor;
+
+				} else {
+
+					spherical.theta += sphericalDelta.theta;
+					spherical.phi += sphericalDelta.phi;
+
+				}
+
+				// restrict theta to be between desired limits
+
+				let min = scope.minAzimuthAngle;
+				let max = scope.maxAzimuthAngle;
+
+				if ( isFinite( min ) && isFinite( max ) ) {
+
+					if ( min < - Math.PI ) min += twoPI; else if ( min > Math.PI ) min -= twoPI;
+
+					if ( max < - Math.PI ) max += twoPI; else if ( max > Math.PI ) max -= twoPI;
+
+					if ( min <= max ) {
+
+						spherical.theta = Math.max( min, Math.min( max, spherical.theta ) );
+
+					} else {
+
+						spherical.theta = ( spherical.theta > ( min + max ) / 2 ) ?
+							Math.max( min, spherical.theta ) :
+							Math.min( max, spherical.theta );
+
+					}
+
+				}
+
+				// restrict phi to be between desired limits
+				spherical.phi = Math.max( scope.minPolarAngle, Math.min( scope.maxPolarAngle, spherical.phi ) );
+
+				spherical.makeSafe();
+
+
+				// move target to panned location
+
+				if ( scope.enableDamping === true ) {
+
+					scope.target.addScaledVector( panOffset, scope.dampingFactor );
+
+				} else {
+
+					scope.target.add( panOffset );
+
+				}
+
+				// Limit the target distance from the cursor to create a sphere around the center of interest
+				scope.target.sub( scope.cursor );
+				scope.target.clampLength( scope.minTargetRadius, scope.maxTargetRadius );
+				scope.target.add( scope.cursor );
+
+				// adjust the camera position based on zoom only if we're not zooming to the cursor or if it's an ortho camera
+				// we adjust zoom later in these cases
+				if ( scope.zoomToCursor && performCursorZoom || scope.object.isOrthographicCamera ) {
+
+					spherical.radius = clampDistance( spherical.radius );
+
+				} else {
+
+					spherical.radius = clampDistance( spherical.radius * scale );
+
+				}
+
+				offset.setFromSpherical( spherical );
+
+				// rotate offset back to "camera-up-vector-is-up" space
+				offset.applyQuaternion( quatInverse );
+
+				position.copy( scope.target ).add( offset );
+
+				scope.object.lookAt( scope.target );
+
+				if ( scope.enableDamping === true ) {
+
+					sphericalDelta.theta *= ( 1 - scope.dampingFactor );
+					sphericalDelta.phi *= ( 1 - scope.dampingFactor );
+
+					panOffset.multiplyScalar( 1 - scope.dampingFactor );
+
+				} else {
+
+					sphericalDelta.set( 0, 0, 0 );
+
+					panOffset.set( 0, 0, 0 );
+
+				}
+
+				// adjust camera position
+				let zoomChanged = false;
+				if ( scope.zoomToCursor && performCursorZoom ) {
+
+					let newRadius = null;
+					if ( scope.object.isPerspectiveCamera ) {
+
+						// move the camera down the pointer ray
+						// this method avoids floating point error
+						const prevRadius = offset.length();
+						newRadius = clampDistance( prevRadius * scale );
+
+						const radiusDelta = prevRadius - newRadius;
+						scope.object.position.addScaledVector( dollyDirection, radiusDelta );
+						scope.object.updateMatrixWorld();
+
+					} else if ( scope.object.isOrthographicCamera ) {
+
+						// adjust the ortho camera position based on zoom changes
+						const mouseBefore = new Vector3( mouse.x, mouse.y, 0 );
+						mouseBefore.unproject( scope.object );
+
+						scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom / scale ) );
+						scope.object.updateProjectionMatrix();
+						zoomChanged = true;
+
+						const mouseAfter = new Vector3( mouse.x, mouse.y, 0 );
+						mouseAfter.unproject( scope.object );
+
+						scope.object.position.sub( mouseAfter ).add( mouseBefore );
+						scope.object.updateMatrixWorld();
+
+						newRadius = offset.length();
+
+					} else {
+
+						console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - zoom to cursor disabled.' );
+						scope.zoomToCursor = false;
+
+					}
+
+					// handle the placement of the target
+					if ( newRadius !== null ) {
+
+						if ( this.screenSpacePanning ) {
+
+							// position the orbit target in front of the new camera position
+							scope.target.set( 0, 0, - 1 )
+								.transformDirection( scope.object.matrix )
+								.multiplyScalar( newRadius )
+								.add( scope.object.position );
+
+						} else {
+
+							// get the ray and translation plane to compute target
+							_ray.origin.copy( scope.object.position );
+							_ray.direction.set( 0, 0, - 1 ).transformDirection( scope.object.matrix );
+
+							// if the camera is 20 degrees above the horizon then don't adjust the focus target to avoid
+							// extremely large values
+							if ( Math.abs( scope.object.up.dot( _ray.direction ) ) < TILT_LIMIT ) {
+
+								object.lookAt( scope.target );
+
+							} else {
+
+								_plane.setFromNormalAndCoplanarPoint( scope.object.up, scope.target );
+								_ray.intersectPlane( _plane, scope.target );
+
+							}
+
+						}
+
+					}
+
+				} else if ( scope.object.isOrthographicCamera ) {
+
+					scope.object.zoom = Math.max( scope.minZoom, Math.min( scope.maxZoom, scope.object.zoom / scale ) );
+					scope.object.updateProjectionMatrix();
+					zoomChanged = true;
+
+				}
+
+				scale = 1;
+				performCursorZoom = false;
+
+				// update condition is:
+				// min(camera displacement, camera rotation in radians)^2 > EPS
+				// using small-angle approximation cos(x/2) = 1 - x^2 / 8
+
+				if ( zoomChanged ||
+					lastPosition.distanceToSquared( scope.object.position ) > EPS ||
+					8 * ( 1 - lastQuaternion.dot( scope.object.quaternion ) ) > EPS ||
+					lastTargetPosition.distanceToSquared( scope.target ) > 0 ) {
+
+					scope.dispatchEvent( _changeEvent );
+
+					lastPosition.copy( scope.object.position );
+					lastQuaternion.copy( scope.object.quaternion );
+					lastTargetPosition.copy( scope.target );
+
+					return true;
+
+				}
+
+				return false;
+
+			};
+
+		}();
+
+		this.dispose = function () {
+
+			scope.domElement.removeEventListener( 'contextmenu', onContextMenu );
+
+			scope.domElement.removeEventListener( 'pointerdown', onPointerDown );
+			scope.domElement.removeEventListener( 'pointercancel', onPointerUp );
+			scope.domElement.removeEventListener( 'wheel', onMouseWheel );
+
+			scope.domElement.removeEventListener( 'pointermove', onPointerMove );
+			scope.domElement.removeEventListener( 'pointerup', onPointerUp );
+
+
+			if ( scope._domElementKeyEvents !== null ) {
+
+				scope._domElementKeyEvents.removeEventListener( 'keydown', onKeyDown );
+				scope._domElementKeyEvents = null;
+
+			}
+
+			//scope.dispatchEvent( { type: 'dispose' } ); // should this be added here?
+
+		};
+
+		//
+		// internals
+		//
+
+		const scope = this;
+
+		const STATE = {
+			NONE: - 1,
+			ROTATE: 0,
+			DOLLY: 1,
+			PAN: 2,
+			TOUCH_ROTATE: 3,
+			TOUCH_PAN: 4,
+			TOUCH_DOLLY_PAN: 5,
+			TOUCH_DOLLY_ROTATE: 6
+		};
+
+		let state = STATE.NONE;
+
+		const EPS = 0.000001;
+
+		// current position in spherical coordinates
+		const spherical = new Spherical();
+		const sphericalDelta = new Spherical();
+
+		let scale = 1;
+		const panOffset = new Vector3();
+
+		const rotateStart = new Vector2();
+		const rotateEnd = new Vector2();
+		const rotateDelta = new Vector2();
+
+		const panStart = new Vector2();
+		const panEnd = new Vector2();
+		const panDelta = new Vector2();
+
+		const dollyStart = new Vector2();
+		const dollyEnd = new Vector2();
+		const dollyDelta = new Vector2();
+
+		const dollyDirection = new Vector3();
+		const mouse = new Vector2();
+		let performCursorZoom = false;
+
+		const pointers = [];
+		const pointerPositions = {};
+
+		function getAutoRotationAngle( deltaTime ) {
+
+			if ( deltaTime !== null ) {
+
+				return ( 2 * Math.PI / 60 * scope.autoRotateSpeed ) * deltaTime;
+
+			} else {
+
+				return 2 * Math.PI / 60 / 60 * scope.autoRotateSpeed;
+
+			}
+
+		}
+
+		function getZoomScale( delta ) {
+
+			const normalized_delta = Math.abs( delta ) / ( 100 * ( window.devicePixelRatio | 0 ) );
+			return Math.pow( 0.95, scope.zoomSpeed * normalized_delta );
+
+		}
+
+		function rotateLeft( angle ) {
+
+			sphericalDelta.theta -= angle;
+
+		}
+
+		function rotateUp( angle ) {
+
+			sphericalDelta.phi -= angle;
+
+		}
+
+		const panLeft = function () {
+
+			const v = new Vector3();
+
+			return function panLeft( distance, objectMatrix ) {
+
+				v.setFromMatrixColumn( objectMatrix, 0 ); // get X column of objectMatrix
+				v.multiplyScalar( - distance );
+
+				panOffset.add( v );
+
+			};
+
+		}();
+
+		const panUp = function () {
+
+			const v = new Vector3();
+
+			return function panUp( distance, objectMatrix ) {
+
+				if ( scope.screenSpacePanning === true ) {
+
+					v.setFromMatrixColumn( objectMatrix, 1 );
+
+				} else {
+
+					v.setFromMatrixColumn( objectMatrix, 0 );
+					v.crossVectors( scope.object.up, v );
+
+				}
+
+				v.multiplyScalar( distance );
+
+				panOffset.add( v );
+
+			};
+
+		}();
+
+		// deltaX and deltaY are in pixels; right and down are positive
+		const pan = function () {
+
+			const offset = new Vector3();
+
+			return function pan( deltaX, deltaY ) {
+
+				const element = scope.domElement;
+
+				if ( scope.object.isPerspectiveCamera ) {
+
+					// perspective
+					const position = scope.object.position;
+					offset.copy( position ).sub( scope.target );
+					let targetDistance = offset.length();
+
+					// half of the fov is center to top of screen
+					targetDistance *= Math.tan( ( scope.object.fov / 2 ) * Math.PI / 180.0 );
+
+					// we use only clientHeight here so aspect ratio does not distort speed
+					panLeft( 2 * deltaX * targetDistance / element.clientHeight, scope.object.matrix );
+					panUp( 2 * deltaY * targetDistance / element.clientHeight, scope.object.matrix );
+
+				} else if ( scope.object.isOrthographicCamera ) {
+
+					// orthographic
+					panLeft( deltaX * ( scope.object.right - scope.object.left ) / scope.object.zoom / element.clientWidth, scope.object.matrix );
+					panUp( deltaY * ( scope.object.top - scope.object.bottom ) / scope.object.zoom / element.clientHeight, scope.object.matrix );
+
+				} else {
+
+					// camera neither orthographic nor perspective
+					console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - pan disabled.' );
+					scope.enablePan = false;
+
+				}
+
+			};
+
+		}();
+
+		function dollyOut( dollyScale ) {
+
+			if ( scope.object.isPerspectiveCamera || scope.object.isOrthographicCamera ) {
+
+				scale /= dollyScale;
+
+			} else {
+
+				console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - dolly/zoom disabled.' );
+				scope.enableZoom = false;
+
+			}
+
+		}
+
+		function dollyIn( dollyScale ) {
+
+			if ( scope.object.isPerspectiveCamera || scope.object.isOrthographicCamera ) {
+
+				scale *= dollyScale;
+
+			} else {
+
+				console.warn( 'WARNING: OrbitControls.js encountered an unknown camera type - dolly/zoom disabled.' );
+				scope.enableZoom = false;
+
+			}
+
+		}
+
+		function updateZoomParameters( x, y ) {
+
+			if ( ! scope.zoomToCursor ) {
+
+				return;
+
+			}
+
+			performCursorZoom = true;
+
+			const rect = scope.domElement.getBoundingClientRect();
+			const dx = x - rect.left;
+			const dy = y - rect.top;
+			const w = rect.width;
+			const h = rect.height;
+
+			mouse.x = ( dx / w ) * 2 - 1;
+			mouse.y = - ( dy / h ) * 2 + 1;
+
+			dollyDirection.set( mouse.x, mouse.y, 1 ).unproject( scope.object ).sub( scope.object.position ).normalize();
+
+		}
+
+		function clampDistance( dist ) {
+
+			return Math.max( scope.minDistance, Math.min( scope.maxDistance, dist ) );
+
+		}
+
+		//
+		// event callbacks - update the object state
+		//
+
+		function handleMouseDownRotate( event ) {
+
+			rotateStart.set( event.clientX, event.clientY );
+
+		}
+
+		function handleMouseDownDolly( event ) {
+
+			updateZoomParameters( event.clientX, event.clientX );
+			dollyStart.set( event.clientX, event.clientY );
+
+		}
+
+		function handleMouseDownPan( event ) {
+
+			panStart.set( event.clientX, event.clientY );
+
+		}
+
+		function handleMouseMoveRotate( event ) {
+
+			rotateEnd.set( event.clientX, event.clientY );
+
+			rotateDelta.subVectors( rotateEnd, rotateStart ).multiplyScalar( scope.rotateSpeed );
+
+			const element = scope.domElement;
+
+			rotateLeft( 2 * Math.PI * rotateDelta.x / element.clientHeight ); // yes, height
+
+			rotateUp( 2 * Math.PI * rotateDelta.y / element.clientHeight );
+
+			rotateStart.copy( rotateEnd );
+
+			scope.update();
+
+		}
+
+		function handleMouseMoveDolly( event ) {
+
+			dollyEnd.set( event.clientX, event.clientY );
+
+			dollyDelta.subVectors( dollyEnd, dollyStart );
+
+			if ( dollyDelta.y > 0 ) {
+
+				dollyOut( getZoomScale( dollyDelta.y ) );
+
+			} else if ( dollyDelta.y < 0 ) {
+
+				dollyIn( getZoomScale( dollyDelta.y ) );
+
+			}
+
+			dollyStart.copy( dollyEnd );
+
+			scope.update();
+
+		}
+
+		function handleMouseMovePan( event ) {
+
+			panEnd.set( event.clientX, event.clientY );
+
+			panDelta.subVectors( panEnd, panStart ).multiplyScalar( scope.panSpeed );
+
+			pan( panDelta.x, panDelta.y );
+
+			panStart.copy( panEnd );
+
+			scope.update();
+
+		}
+
+		function handleMouseWheel( event ) {
+
+			updateZoomParameters( event.clientX, event.clientY );
+
+			if ( event.deltaY < 0 ) {
+
+				dollyIn( getZoomScale( event.deltaY ) );
+
+			} else if ( event.deltaY > 0 ) {
+
+				dollyOut( getZoomScale( event.deltaY ) );
+
+			}
+
+			scope.update();
+
+		}
+
+		function handleKeyDown( event ) {
+
+			let needsUpdate = false;
+
+			switch ( event.code ) {
+
+				case scope.keys.UP:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						rotateUp( 2 * Math.PI * scope.rotateSpeed / scope.domElement.clientHeight );
+
+					} else {
+
+						pan( 0, scope.keyPanSpeed );
+
+					}
+
+					needsUpdate = true;
+					break;
+
+				case scope.keys.BOTTOM:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						rotateUp( - 2 * Math.PI * scope.rotateSpeed / scope.domElement.clientHeight );
+
+					} else {
+
+						pan( 0, - scope.keyPanSpeed );
+
+					}
+
+					needsUpdate = true;
+					break;
+
+				case scope.keys.LEFT:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						rotateLeft( 2 * Math.PI * scope.rotateSpeed / scope.domElement.clientHeight );
+
+					} else {
+
+						pan( scope.keyPanSpeed, 0 );
+
+					}
+
+					needsUpdate = true;
+					break;
+
+				case scope.keys.RIGHT:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						rotateLeft( - 2 * Math.PI * scope.rotateSpeed / scope.domElement.clientHeight );
+
+					} else {
+
+						pan( - scope.keyPanSpeed, 0 );
+
+					}
+
+					needsUpdate = true;
+					break;
+
+			}
+
+			if ( needsUpdate ) {
+
+				// prevent the browser from scrolling on cursor keys
+				event.preventDefault();
+
+				scope.update();
+
+			}
+
+
+		}
+
+		function handleTouchStartRotate( event ) {
+
+			if ( pointers.length === 1 ) {
+
+				rotateStart.set( event.pageX, event.pageY );
+
+			} else {
+
+				const position = getSecondPointerPosition( event );
+
+				const x = 0.5 * ( event.pageX + position.x );
+				const y = 0.5 * ( event.pageY + position.y );
+
+				rotateStart.set( x, y );
+
+			}
+
+		}
+
+		function handleTouchStartPan( event ) {
+
+			if ( pointers.length === 1 ) {
+
+				panStart.set( event.pageX, event.pageY );
+
+			} else {
+
+				const position = getSecondPointerPosition( event );
+
+				const x = 0.5 * ( event.pageX + position.x );
+				const y = 0.5 * ( event.pageY + position.y );
+
+				panStart.set( x, y );
+
+			}
+
+		}
+
+		function handleTouchStartDolly( event ) {
+
+			const position = getSecondPointerPosition( event );
+
+			const dx = event.pageX - position.x;
+			const dy = event.pageY - position.y;
+
+			const distance = Math.sqrt( dx * dx + dy * dy );
+
+			dollyStart.set( 0, distance );
+
+		}
+
+		function handleTouchStartDollyPan( event ) {
+
+			if ( scope.enableZoom ) handleTouchStartDolly( event );
+
+			if ( scope.enablePan ) handleTouchStartPan( event );
+
+		}
+
+		function handleTouchStartDollyRotate( event ) {
+
+			if ( scope.enableZoom ) handleTouchStartDolly( event );
+
+			if ( scope.enableRotate ) handleTouchStartRotate( event );
+
+		}
+
+		function handleTouchMoveRotate( event ) {
+
+			if ( pointers.length == 1 ) {
+
+				rotateEnd.set( event.pageX, event.pageY );
+
+			} else {
+
+				const position = getSecondPointerPosition( event );
+
+				const x = 0.5 * ( event.pageX + position.x );
+				const y = 0.5 * ( event.pageY + position.y );
+
+				rotateEnd.set( x, y );
+
+			}
+
+			rotateDelta.subVectors( rotateEnd, rotateStart ).multiplyScalar( scope.rotateSpeed );
+
+			const element = scope.domElement;
+
+			rotateLeft( 2 * Math.PI * rotateDelta.x / element.clientHeight ); // yes, height
+
+			rotateUp( 2 * Math.PI * rotateDelta.y / element.clientHeight );
+
+			rotateStart.copy( rotateEnd );
+
+		}
+
+		function handleTouchMovePan( event ) {
+
+			if ( pointers.length === 1 ) {
+
+				panEnd.set( event.pageX, event.pageY );
+
+			} else {
+
+				const position = getSecondPointerPosition( event );
+
+				const x = 0.5 * ( event.pageX + position.x );
+				const y = 0.5 * ( event.pageY + position.y );
+
+				panEnd.set( x, y );
+
+			}
+
+			panDelta.subVectors( panEnd, panStart ).multiplyScalar( scope.panSpeed );
+
+			pan( panDelta.x, panDelta.y );
+
+			panStart.copy( panEnd );
+
+		}
+
+		function handleTouchMoveDolly( event ) {
+
+			const position = getSecondPointerPosition( event );
+
+			const dx = event.pageX - position.x;
+			const dy = event.pageY - position.y;
+
+			const distance = Math.sqrt( dx * dx + dy * dy );
+
+			dollyEnd.set( 0, distance );
+
+			dollyDelta.set( 0, Math.pow( dollyEnd.y / dollyStart.y, scope.zoomSpeed ) );
+
+			dollyOut( dollyDelta.y );
+
+			dollyStart.copy( dollyEnd );
+
+			const centerX = ( event.pageX + position.x ) * 0.5;
+			const centerY = ( event.pageY + position.y ) * 0.5;
+
+			updateZoomParameters( centerX, centerY );
+
+		}
+
+		function handleTouchMoveDollyPan( event ) {
+
+			if ( scope.enableZoom ) handleTouchMoveDolly( event );
+
+			if ( scope.enablePan ) handleTouchMovePan( event );
+
+		}
+
+		function handleTouchMoveDollyRotate( event ) {
+
+			if ( scope.enableZoom ) handleTouchMoveDolly( event );
+
+			if ( scope.enableRotate ) handleTouchMoveRotate( event );
+
+		}
+
+		//
+		// event handlers - FSM: listen for events and reset state
+		//
+
+		function onPointerDown( event ) {
+
+			if ( scope.enabled === false ) return;
+
+			if ( pointers.length === 0 ) {
+
+				scope.domElement.setPointerCapture( event.pointerId );
+
+				scope.domElement.addEventListener( 'pointermove', onPointerMove );
+				scope.domElement.addEventListener( 'pointerup', onPointerUp );
+
+			}
+
+			//
+
+			addPointer( event );
+
+			if ( event.pointerType === 'touch' ) {
+
+				onTouchStart( event );
+
+			} else {
+
+				onMouseDown( event );
+
+			}
+
+		}
+
+		function onPointerMove( event ) {
+
+			if ( scope.enabled === false ) return;
+
+			if ( event.pointerType === 'touch' ) {
+
+				onTouchMove( event );
+
+			} else {
+
+				onMouseMove( event );
+
+			}
+
+		}
+
+		function onPointerUp( event ) {
+
+			removePointer( event );
+
+			if ( pointers.length === 0 ) {
+
+				scope.domElement.releasePointerCapture( event.pointerId );
+
+				scope.domElement.removeEventListener( 'pointermove', onPointerMove );
+				scope.domElement.removeEventListener( 'pointerup', onPointerUp );
+
+			}
+
+			scope.dispatchEvent( _endEvent );
+
+			state = STATE.NONE;
+
+		}
+
+		function onMouseDown( event ) {
+
+			let mouseAction;
+
+			switch ( event.button ) {
+
+				case 0:
+
+					mouseAction = scope.mouseButtons.LEFT;
+					break;
+
+				case 1:
+
+					mouseAction = scope.mouseButtons.MIDDLE;
+					break;
+
+				case 2:
+
+					mouseAction = scope.mouseButtons.RIGHT;
+					break;
+
+				default:
+
+					mouseAction = - 1;
+
+			}
+
+			switch ( mouseAction ) {
+
+				case MOUSE.DOLLY:
+
+					if ( scope.enableZoom === false ) return;
+
+					handleMouseDownDolly( event );
+
+					state = STATE.DOLLY;
+
+					break;
+
+				case MOUSE.ROTATE:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						if ( scope.enablePan === false ) return;
+
+						handleMouseDownPan( event );
+
+						state = STATE.PAN;
+
+					} else {
+
+						if ( scope.enableRotate === false ) return;
+
+						handleMouseDownRotate( event );
+
+						state = STATE.ROTATE;
+
+					}
+
+					break;
+
+				case MOUSE.PAN:
+
+					if ( event.ctrlKey || event.metaKey || event.shiftKey ) {
+
+						if ( scope.enableRotate === false ) return;
+
+						handleMouseDownRotate( event );
+
+						state = STATE.ROTATE;
+
+					} else {
+
+						if ( scope.enablePan === false ) return;
+
+						handleMouseDownPan( event );
+
+						state = STATE.PAN;
+
+					}
+
+					break;
+
+				default:
+
+					state = STATE.NONE;
+
+			}
+
+			if ( state !== STATE.NONE ) {
+
+				scope.dispatchEvent( _startEvent );
+
+			}
+
+		}
+
+		function onMouseMove( event ) {
+
+			switch ( state ) {
+
+				case STATE.ROTATE:
+
+					if ( scope.enableRotate === false ) return;
+
+					handleMouseMoveRotate( event );
+
+					break;
+
+				case STATE.DOLLY:
+
+					if ( scope.enableZoom === false ) return;
+
+					handleMouseMoveDolly( event );
+
+					break;
+
+				case STATE.PAN:
+
+					if ( scope.enablePan === false ) return;
+
+					handleMouseMovePan( event );
+
+					break;
+
+			}
+
+		}
+
+		function onMouseWheel( event ) {
+
+			if ( scope.enabled === false || scope.enableZoom === false || state !== STATE.NONE ) return;
+
+			event.preventDefault();
+
+			scope.dispatchEvent( _startEvent );
+
+			handleMouseWheel( event );
+
+			scope.dispatchEvent( _endEvent );
+
+		}
+
+		function onKeyDown( event ) {
+
+			if ( scope.enabled === false || scope.enablePan === false ) return;
+
+			handleKeyDown( event );
+
+		}
+
+		function onTouchStart( event ) {
+
+			trackPointer( event );
+
+			switch ( pointers.length ) {
+
+				case 1:
+
+					switch ( scope.touches.ONE ) {
+
+						case TOUCH.ROTATE:
+
+							if ( scope.enableRotate === false ) return;
+
+							handleTouchStartRotate( event );
+
+							state = STATE.TOUCH_ROTATE;
+
+							break;
+
+						case TOUCH.PAN:
+
+							if ( scope.enablePan === false ) return;
+
+							handleTouchStartPan( event );
+
+							state = STATE.TOUCH_PAN;
+
+							break;
+
+						default:
+
+							state = STATE.NONE;
+
+					}
+
+					break;
+
+				case 2:
+
+					switch ( scope.touches.TWO ) {
+
+						case TOUCH.DOLLY_PAN:
+
+							if ( scope.enableZoom === false && scope.enablePan === false ) return;
+
+							handleTouchStartDollyPan( event );
+
+							state = STATE.TOUCH_DOLLY_PAN;
+
+							break;
+
+						case TOUCH.DOLLY_ROTATE:
+
+							if ( scope.enableZoom === false && scope.enableRotate === false ) return;
+
+							handleTouchStartDollyRotate( event );
+
+							state = STATE.TOUCH_DOLLY_ROTATE;
+
+							break;
+
+						default:
+
+							state = STATE.NONE;
+
+					}
+
+					break;
+
+				default:
+
+					state = STATE.NONE;
+
+			}
+
+			if ( state !== STATE.NONE ) {
+
+				scope.dispatchEvent( _startEvent );
+
+			}
+
+		}
+
+		function onTouchMove( event ) {
+
+			trackPointer( event );
+
+			switch ( state ) {
+
+				case STATE.TOUCH_ROTATE:
+
+					if ( scope.enableRotate === false ) return;
+
+					handleTouchMoveRotate( event );
+
+					scope.update();
+
+					break;
+
+				case STATE.TOUCH_PAN:
+
+					if ( scope.enablePan === false ) return;
+
+					handleTouchMovePan( event );
+
+					scope.update();
+
+					break;
+
+				case STATE.TOUCH_DOLLY_PAN:
+
+					if ( scope.enableZoom === false && scope.enablePan === false ) return;
+
+					handleTouchMoveDollyPan( event );
+
+					scope.update();
+
+					break;
+
+				case STATE.TOUCH_DOLLY_ROTATE:
+
+					if ( scope.enableZoom === false && scope.enableRotate === false ) return;
+
+					handleTouchMoveDollyRotate( event );
+
+					scope.update();
+
+					break;
+
+				default:
+
+					state = STATE.NONE;
+
+			}
+
+		}
+
+		function onContextMenu( event ) {
+
+			if ( scope.enabled === false ) return;
+
+			event.preventDefault();
+
+		}
+
+		function addPointer( event ) {
+
+			pointers.push( event.pointerId );
+
+		}
+
+		function removePointer( event ) {
+
+			delete pointerPositions[ event.pointerId ];
+
+			for ( let i = 0; i < pointers.length; i ++ ) {
+
+				if ( pointers[ i ] == event.pointerId ) {
+
+					pointers.splice( i, 1 );
+					return;
+
+				}
+
+			}
+
+		}
+
+		function trackPointer( event ) {
+
+			let position = pointerPositions[ event.pointerId ];
+
+			if ( position === undefined ) {
+
+				position = new Vector2();
+				pointerPositions[ event.pointerId ] = position;
+
+			}
+
+			position.set( event.pageX, event.pageY );
+
+		}
+
+		function getSecondPointerPosition( event ) {
+
+			const pointerId = ( event.pointerId === pointers[ 0 ] ) ? pointers[ 1 ] : pointers[ 0 ];
+
+			return pointerPositions[ pointerId ];
+
+		}
+
+		//
+
+		scope.domElement.addEventListener( 'contextmenu', onContextMenu );
+
+		scope.domElement.addEventListener( 'pointerdown', onPointerDown );
+		scope.domElement.addEventListener( 'pointercancel', onPointerUp );
+		scope.domElement.addEventListener( 'wheel', onMouseWheel, { passive: false } );
+
+		// force an update at start
+
+		this.update();
+
+	}
+
+}
+
+export { OrbitControls };
diff --git a/public/vendor/three-setup.js b/public/vendor/three-setup.js
index a7a7c0b..7fe818a 100644
--- a/public/vendor/three-setup.js
+++ b/public/vendor/three-setup.js
@@ -1,5 +1,7 @@
 import * as THREE from 'three';
 import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
+import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
 
 window.THREE = THREE;
 window.GLTFLoader = GLTFLoader;
+window.OrbitControls = OrbitControls;
diff --git a/src/SomhairlesDream.Frontend/App.fs b/src/SomhairlesDream.Frontend/App.fs
index ec9e273..e6edd51 100644
--- a/src/SomhairlesDream.Frontend/App.fs
+++ b/src/SomhairlesDream.Frontend/App.fs
@@ -47,7 +47,14 @@ type ViewState =
       Scene: ThreeNode
       Camera: ThreeCamera
       Group: ThreeNode
-      Canvas: HTMLCanvasElement }
+      Canvas: HTMLCanvasElement
+      Controls: obj }
+
+// Auto-spin pauses while the visitor is dragging or zooming the model and
+// resumes a few seconds after the last interaction, so inspecting a stage
+// (dish, RTG, mast) is never fought by the idle animation.
+let mutable lastInteractionMs = 0.0
+let idleSpinDelayMs = 3500.0
 
 type LoadOwner =
     { ProjectId: string
@@ -199,6 +206,14 @@ let frameObject (view: ViewState) (node: ThreeNode) =
             camera.lookAt(0.0, 0.0, 0.0)
             camera.updateProjectionMatrix ()
 
+            // Re-sync the orbit target after every auto-fit so drag/zoom
+            // pivots around the freshly centered model.
+            match view.Controls with
+            | null -> ()
+            | controls ->
+                setControlsTarget controls 0.0 0.0 0.0
+                updateControls controls
+
 let resizeView (view: ViewState) =
     let width = max 1.0 (float view.Canvas.clientWidth)
     let height = max 1.0 (float view.Canvas.clientHeight)
@@ -230,7 +245,7 @@ let initializeView () =
     scene.background <- createColor("#11171a")
     let camera = createPerspectiveCamera(34.0, width / height, 0.1, 100.0)
     camera.position.set(6.4, 4.6, 7.2) |> ignore
-    camera.lookAt(0.0, 1.2, 0.0)
+    camera.lookAt(0.0, 0.0, 0.0)
     let group = createGroup()
     scene.add(group)
     scene.add(createAmbientLight("#f0e6c8", 1.9))
@@ -238,23 +253,40 @@ let initializeView () =
     keyLight.position.set(4.0, 7.0, 5.0) |> ignore
     scene.add(keyLight)
 
+    let controls = createOrbitControls camera canvas
+    setControlsTarget controls 0.0 0.0 0.0
+    setControlsDamping controls true
+    setControlsAutoRotateSpeed controls 0.7
+
     let view =
         { Renderer = renderer
           Scene = scene
           Camera = camera
           Group = group
-          Canvas = canvas }
+          Canvas = canvas
+          Controls = controls }
 
     viewState <- Some view
+
     freezeRotation <- (queryParam "freeze") = "1"
-    exposeViewerDebug camera scene group canvas
+    setControlsAutoRotate controls (not freezeRotation)
+    exposeViewerDebug camera scene group canvas controls
     renderFrame selectedFrame
     window.addEventListener("resize", fun _ -> resizeView view)
 
-    let rec animate (_: float) =
+    canvas.addEventListener("pointerdown", fun _ -> lastInteractionMs <- JS.Constructors.Date.now ())
+    canvas.addEventListener("wheel", fun _ -> lastInteractionMs <- JS.Constructors.Date.now ())
+    canvas.addEventListener("touchstart", fun _ -> lastInteractionMs <- JS.Constructors.Date.now ())
+
+    let rec animate (nowMs: float) =
+        updateControls controls
+
         if not freezeRotation then
             group.rotation.y <- group.rotation.y + 0.003
 
+        let interacting = nowMs - lastInteractionMs < idleSpinDelayMs
+        setControlsAutoRotate controls (not freezeRotation && not interacting)
+
         renderer.render(scene, camera)
         requestAnimationFrame animate |> ignore
 
diff --git a/src/SomhairlesDream.Frontend/Bindings.fs b/src/SomhairlesDream.Frontend/Bindings.fs
index e7c567d..19056a5 100644
--- a/src/SomhairlesDream.Frontend/Bindings.fs
+++ b/src/SomhairlesDream.Frontend/Bindings.fs
@@ -65,6 +65,24 @@ let createGLTFLoader () : obj = jsNative
 [<Emit("$0.load($1, $2, null, $3)")>]
 let loadGLTF (loader: obj) (url: string) (onLoad: GLTFScene -> unit) (onError: obj -> unit) : unit = jsNative
 
+[<Emit("new OrbitControls($0, $1)")>]
+let createOrbitControls (camera: obj) (canvas: obj) : obj = jsNative
+
+[<Emit("$0.target.copy({ x: $1, y: $2, z: $3 })")>]
+let setControlsTarget (controls: obj) (x: float) (y: float) (z: float) : unit = jsNative
+
+[<Emit("$0.enableDamping = $1")>]
+let setControlsDamping (controls: obj) (enabled: bool) : unit = jsNative
+
+[<Emit("$0.autoRotate = $1")>]
+let setControlsAutoRotate (controls: obj) (auto: bool) : unit = jsNative
+
+[<Emit("$0.autoRotateSpeed = $1")>]
+let setControlsAutoRotateSpeed (controls: obj) (speed: float) : unit = jsNative
+
+[<Emit("$0.update()")>]
+let updateControls (controls: obj) : unit = jsNative
+
 [<Emit("new URLSearchParams(window.location.search).get($0)")>]
 let queryParam (name: string) : string = jsNative
 
@@ -100,8 +118,8 @@ let createBox3 () : ThreeBox3 = jsNative
 [<Emit("new THREE.Vector3()")>]
 let createVector3 () : ThreeVector = jsNative
 
-[<Emit("window.SOMHAIRLES_VIEWER = { camera: $0, scene: $1, group: $2, canvas: $3 }")>]
-let exposeViewerDebug (camera: ThreeCamera) (scene: ThreeNode) (group: ThreeNode) (canvas: obj) : unit = jsNative
+[<Emit("window.SOMHAIRLES_VIEWER = { camera: $0, scene: $1, group: $2, canvas: $3, controls: $4 }")>]
+let exposeViewerDebug (camera: ThreeCamera) (scene: ThreeNode) (group: ThreeNode) (canvas: obj) (controls: obj) : unit = jsNative
 
 [<Emit("var child; while ((child = $0.firstChild)) { $0.removeChild(child); }")>]
 let clearChildren (node: obj) : unit = jsNative