oscen | Rust Sound Synthesis Library | Audio Utils library

I have a scene where I want to combine perspective objects (ie. objects that appear smaller when they are far away) with orthogographic objects (ie. objects that appear the same size irrespective of distance). The perspective objects are part of the rendered "world", while the orthogographic objects are adornments, like labels or icons. Unlike a HUD, I want the orthogographic objects to be rendered "within" the world, which means that they can be covered by world objects (imagine a plane passing before a label).

My solution is to use one renderer, but two scenes, one with a PerspectiveCamera and one with an OrthogographicCamera. I render them in sequence without clearing the z buffer (the renderer's autoClear property is set to false). The problem that I am facing is that I need to synchronize the placement of the objects in each scene so that an object in one scene is assigned a z-position that is behind objects in the other scene that are before it, but before objects that are behind it.

To do that, I am designating my perspective scene as the "leading" scene, ie. all coordinates of all objects (perspective and orthogographic) are assigned based on this scene. The perspective objects use these coordinates directly and are rendered within that scene and with the perspective camera. The coordinates of the orthogographic objects are transformed to the coordinates in the orthogographic scene and then rendered in that scene with the orthogographic camera. I do the transformation by projecting the coordinates in the perspective scene to the perspective camera's view pane and then back to the orthogonal scene with the orthogographic camera: