If someone can say me how to convert xyz point + xy rotation to a xy point ... It'll be great better for the project.
here is some GML code for converting a 3d point to a 2d point onscreen. It's just handling variables, so if you've ever programmed before(in any language), you should understand the code.
It's based on floating points, so it might be a bit difficulty to port.
the code to convert 3d to 2d returns a number between -1 and 1 for the x and y variables.
If you don't understand the 3d therms, just ask me.
I'm also porting this code to asm for my 3d engine
the code (GML version) has been fully tested and no bugs were found