Circular Floors

Hello, I have created a round room, however, I would like to put rectangular wooden floor planks in it. How do I trim the squareness of the floor to the roundness of the room without having to use a graphic application? Thanks--

Your best bet would be a graphic application, both for performance, and because Roll20 is not a full-featured drawing app. You cannot fill or mask areas like you describe. And in general, performance increases as the number of objects in a map decreases. That being said, if the area outside the round room does not "exist", i.e. is not a playable area, you can mask off areas by drawing free-form shapes that are the same color as the page background.