要在不使用TransformableNode的情况下旋转模型，可以使用AR Session的onUpdate方法来手动更新模型的旋转。

以下是一个使用ARcore和Sceneform的代码示例，展示了如何通过手势旋转模型：

import android.content.Context;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import com.google.ar.core.Anchor;
import com.google.ar.core.Frame;
import com.google.ar.core.HitResult;
import com.google.ar.core.Plane;
import com.google.ar.core.Pose;
import com.google.ar.core.Session;
import com.google.ar.core.Trackable;
import com.google.ar.sceneform.AnchorNode;
import com.google.ar.sceneform.ArSceneView;
import com.google.ar.sceneform.HitTestResult;
import com.google.ar.sceneform.Node;
import com.google.ar.sceneform.math.Quaternion;
import com.google.ar.sceneform.math.Vector3;
import com.google.ar.sceneform.rendering.ModelRenderable;
import com.google.ar.sceneform.ux.ArFragment;
import com.google.ar.sceneform.ux.BaseArFragment;
import com.google.ar.sceneform.ux.TransformableNode;

public class MainActivity extends AppCompatActivity {
    private ArFragment arFragment;
    private ModelRenderable modelRenderable;
    private GestureDetector gestureDetector;
    private Node modelNode;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        arFragment = (ArFragment) getSupportFragmentManager().findFragmentById(R.id.arFragment);

        // 创建手势检测器
        gestureDetector = new GestureDetector(this, new GestureListener());

        // 点击屏幕时加载模型
        arFragment.setOnTapArPlaneListener((hitResult, plane, motionEvent) -> {
            if (modelRenderable == null) {
                ModelRenderable.builder()
                        .setSource(this, Uri.parse("model.sfb"))
                        .build()
                        .thenAccept(renderable -> {
                            modelRenderable = renderable;
                            addModel(hitResult);
                        })
                        .exceptionally(throwable -> {
                            Toast.makeText(this, "无法加载模型", Toast.LENGTH_SHORT).show();
                            return null;
                        });
            } else {
                addModel(hitResult);
            }
        });

        // 设置ArSceneView的触摸监听器
        arFragment.getArSceneView().setOnTouchListener((view, motionEvent) -> {
            return gestureDetector.onTouchEvent(motionEvent);
        });
    }

    private void addModel(HitResult hitResult) {
        Anchor anchor = hitResult.createAnchor();
        AnchorNode anchorNode = new AnchorNode(anchor);
        anchorNode.setParent(arFragment.getArSceneView().getScene());

        modelNode = new Node();
        modelNode.setParent(anchorNode);
        modelNode.setRenderable(modelRenderable);

        // 在指定位置缩放模型
        modelNode.setLocalScale(new Vector3(0.2f, 0.2f, 0.2f));
    }

    private class GestureListener extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onDown(MotionEvent e) {
            return true;
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            if (modelNode != null) {
                // 计算旋转角度
                float deltaX = e2.getX() - e1.getX();
                float deltaY = e2.getY() - e1.getY();
                float rotation = (float) Math.sqrt(deltaX * deltaX + deltaY * deltaY) * 0.5f;

                // 根据旋转角度旋转模型
                Quaternion deltaRotationQuaternion = Quaternion.axisAngle(new Vector3(deltaY, deltaX, 0f), rotation);
                Quaternion modelRotation = modelNode.getLocalRotation();
                Quaternion newModelRotation = Quaternion.multiply(modelRotation, deltaRotationQuaternion);
                modelNode.setLocalRotation(newModelRotation);
            }
            return true;
        }
    }
}

上述代码中，我们在onCreate方法中创建了一个ArFragment，并设置了点击屏幕时加载模型的监听器。当模型加载完成后，我们将其添加到AnchorNode中，并设置了其初始缩放比例。

在ArSceneView的触摸监听器中，我们使用GestureDetector来监听手势，在滑动屏幕时计算旋转角度，并根据旋转角度旋转模型。这样就能够实现在不使用TransformableNode的情况