OrbitControls: fix pinch zoom behaviour

examples/jsm/controls/OrbitControls.js

@@ -483,6 +483,8 @@ class OrbitControls extends EventDispatcher {
 		const pointers = [];
 		const pointerPositions = {};
 
+		let controlActive = false;
+
 		function getAutoRotationAngle( deltaTime ) {
 
 			if ( deltaTime !== null ) {
@@ -499,8 +501,8 @@ class OrbitControls extends EventDispatcher {
 
 		function getZoomScale( delta ) {
 
-			const normalized_delta = Math.abs( delta ) / ( 100 * ( window.devicePixelRatio | 0 ) );
-			return Math.pow( 0.95, scope.zoomSpeed * normalized_delta );
+			const normalizedDelta = Math.abs( delta * 0.01 );
+			return Math.pow( 0.95, scope.zoomSpeed * normalizedDelta );
 
 		}
 
@@ -1207,12 +1209,70 @@ class OrbitControls extends EventDispatcher {
 
 			scope.dispatchEvent( _startEvent );
 
-			handleMouseWheel( event );
+			handleMouseWheel( customWheelEvent( event ) );
 
 			scope.dispatchEvent( _endEvent );
 
 		}
 
+		function customWheelEvent( event ) {
+
+			const mode = event.deltaMode;
+
+			// minimal wheel event altered to meet delta-zoom demand
+			const newEvent = {
+				clientX: event.clientX,
+				clientY: event.clientY,
+				deltaY: event.deltaY,
+			}
+
+			switch ( mode ) {
+
+				case 1: // LINE_MODE
+					newEvent.deltaY *= 16;
+					break;
+
+				case 2: // PAGE_MODE
+					newEvent.deltaY *= 100;
+					break;
+
+			}
+
+			// detect if event was triggered by pinching
+			if ( event.ctrlKey && !controlActive ) {
+
+				newEvent.deltaY *= 10;
+
+			}
+
+			return newEvent;
+
+		}
+
+		function interceptControlDown( event ) {
+
+			if ( event.key === "Control" ) {
+
+				controlActive = true;
+
+				document.addEventListener('keyup', interceptControlUp, { passive: true, capture: true });
+
+			}
+
+		}
+
+		function interceptControlUp( event ) {
+
+			if ( event.key === "Control" ) {
+
+				controlActive = false;
+
+				document.removeEventListener('keyup', interceptControlUp, { passive: true, capture: true });
+
+			}
+
+		}
+
 		function onKeyDown( event ) {
 
 			if ( scope.enabled === false || scope.enablePan === false ) return;
@@ -1421,6 +1481,8 @@ class OrbitControls extends EventDispatcher {
 		scope.domElement.addEventListener( 'pointercancel', onPointerUp );
 		scope.domElement.addEventListener( 'wheel', onMouseWheel, { passive: false } );
 
+		document.addEventListener( 'keydown', interceptControlDown, { passive: true, capture: true } );
+
 		// force an update at start
 
 		this.update();
@@ -1429,4 +1491,4 @@ class OrbitControls extends EventDispatcher {
 
 }
 
-export { OrbitControls };
+export { OrbitControls };