There are quite a few ways. And it also depends on how you want the view helper to look.
- If your view helper is 2D, or you render it to 2D texture - you can use an orthographic camera with depth testing turned off - that’s probably the most popular for creating any UI elements (like in this or this example.)
- You can create a separate canvas DOM element, position it absolutely on the screen - then do something similar to point 1, just render the view helper to the separate canvas.
- If your view helper is 3D, you’d like to render 2D texture on a 3D plane, or you’re just feeling adventurous - you can simply add the viewer directly to the scene and turn off depth testing. Positioning it in a proper location is a matter of doing some calculations, rotation along the camera is just
viewer.quaternion.copy(camera.quaterion). (in the end you’d get something like this.)