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Windows (Dynamic Lighting)

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Main Page: Updated Dynamic Lighting

Windows, in context of Roll20's Dynamic Lighting, are sections of "wall" that allows sight to pass through, but stops movement of tokens. They can be created with APIs.

Example of window (top), and passwall(bottom)



The following API can be used for creating or editing UDL "windows", or similar things.


  • DoorKnocker -- Script helps quickly open and close doors by controlling the dynamic lighting lines.
    • v1.211 Introduces option to create "windows"
  • UDLWindows(Forum) -- API for creating or converting DL lines to be see-through, but still block movement
    • Converting DL circles to windows works
    • sourcecode


A related trick to Windows is to create hidden passages which blocks sight, but doesn't stop movement. Great for illusionary walls, hidden areas, or to limit vision in thick fog.

  • UDLPasswall(Forum) - Walls that block sight, but not movement

History of the Trick

In late 2020, Andreas J. realized that by creating a Free-hand drawing on any of the other b Layers than the DL-layer, and then moving it to the DL layer, it only partially blocked sight, but always blocked movement. After the discovery, TheAaron and Scott C. created APIs that can create windows much easier. Drae Acevedo saw an earlier version of this when using the circle tool.

Until May 2021, it was possible for
info-subscribers to create "windows" by drawing shapes with the free-hand tool on another layer, and then move it to the DL layer. This was due to Roll20 updating Dynamic Lighting to make freehand & eclipse drawings work properly as DL lines, which inadvertently made the windows inaccessible to Plus users.