Download demo: http://www.mediafire.com/download/srt7uf3dd5yyblu/3D+Mirrors.exe
This asset lets you easily implement 3D mirrors into your game. The code is written in GML, but an extra (optional) DLL is used for optimization on windows targets. The mirrors have a customizable reflection depth to give the effect of recursive reflections (if needed), and you can have multiple mirrors in different sizes, orientations, qualities, and with different texture overlays or frame models.
The code is well-organized with lots of comments, and the asset is optimized with efficiency in mind.
Marketplace link: https://marketplace....3367/mirrors-3d