How to setup a WebGLRenderTarget with DepthTexture: three.js examples
How to render to the render target with OrthographicCamera, this is what I could recall quickly: Running in the field of instances
Also, used layers for cameras and objects. For example, when you render with the orthographic camera to the render target, you don’t need it to “see” the rain, so the camera “sees” objects at the layer 1.