If i search for this, i find only how to grid in edit mode. but i want in the game that the player can place 3d Buildings on a grid. How can i do such a grid in 3d?
You would use a GridMap for this.
https://docs.godotengine.org/en/stable/classes/class_gridmap.html
Note, you might have to code the interaction yourself, I don't believe you can use the editor tools in your game but maybe it's possible (never looked into it). If you do it with code you would call "set_cell_item" to set a block in the gripmap to a particular 3D model.
Ok ty. i will read into it