Building occlusion

In any isometric game, one of the classic challenges is figuring out how to show what’s behind buildings and more importantly, how the player can interact with anything hidden by a structure.

I went with a solution that’s simple to implement and is reminiscent of that early 2000s aesthetic: just remove the floor above and use some light artistic cues to suggest you’re now looking into a basement or lower level.

The core of the implementation is straightforward. I pass an opacity value down to the shader using my own game_object structure via the ModernGL wrapper. The flow looks like this:
game engine instruction → ModernGL → shader.vert → shader.frag.

Next up was camera interaction. The idea is simple – whenever the camera is centered on a building and at a pre-defined zoom level, we trigger occlusion to reveal what’s underneath.

Tweaked opacity levels to be dynamic – higher the floor, higher the opacity. Here’s the final result: