Use in-plane rotation when eye and selected gizmo axis are parallel (#26860)

examples/jsm/controls/TransformControls.js

@@ -465,17 +465,9 @@ class TransformControls extends Object3D {
 
 			const ROTATION_SPEED = 20 / this.worldPosition.distanceTo( _tempVector.setFromMatrixPosition( this.camera.matrixWorld ) );
 
-			if ( axis === 'E' ) {
+			let _inPlaneRotation = false;
 
-				this.rotationAxis.copy( this.eye );
-				this.rotationAngle = this.pointEnd.angleTo( this.pointStart );
-
-				this._startNorm.copy( this.pointStart ).normalize();
-				this._endNorm.copy( this.pointEnd ).normalize();
-
-				this.rotationAngle *= ( this._endNorm.cross( this._startNorm ).dot( this.eye ) < 0 ? 1 : - 1 );
-
-			} else if ( axis === 'XYZE' ) {
+			if ( axis === 'XYZE' ) {
 
 				this.rotationAxis.copy( this._offset ).cross( this.eye ).normalize();
 				this.rotationAngle = this._offset.dot( _tempVector.copy( this.rotationAxis ).cross( this.eye ) ) * ROTATION_SPEED;
@@ -492,7 +484,31 @@ class TransformControls extends Object3D {
 
 				}
 
-				this.rotationAngle = this._offset.dot( _tempVector.cross( this.eye ).normalize() ) * ROTATION_SPEED;
+				_tempVector.cross( this.eye );
+
+				// When _tempVector is 0 after cross with this.eye the vectors are parallel and should use in-plane rotation logic.
+				if ( _tempVector.length() === 0 ) {
+
+					_inPlaneRotation = true;
+
+				} else {
+
+					this.rotationAngle = this._offset.dot( _tempVector.normalize() ) * ROTATION_SPEED;
+
+				}
+
+
+			}
+
+			if ( axis === 'E' || _inPlaneRotation ) {
+
+				this.rotationAxis.copy( this.eye );
+				this.rotationAngle = this.pointEnd.angleTo( this.pointStart );
+
+				this._startNorm.copy( this.pointStart ).normalize();
+				this._endNorm.copy( this.pointEnd ).normalize();
+
+				this.rotationAngle *= ( this._endNorm.cross( this._startNorm ).dot( this.eye ) < 0 ? 1 : - 1 );
 
 			}