Measuring 5e Cone Area of Effect

Hey folks. I just figured out a way to draw a free form, sweep-able cone in Roll20 for 5e games. Thought I'd share and get some... thoughts.



You just need to draw the red lines. Step by step instructions:

1. Select the Polygon/Line tool (f, g)
2. Hold shift (snap to grid) and click on an intersection of the grid as spell point of origin.
3. Draw a triangle (by clicking) where the base of the triangle is <spell range> length, and the distance from the centre point of the base is <spell range> from the point of origin.
4. Complete the triangle by right clicking.
5. On the opposite side of the point of origin, at <spell range> distance, draw a short straight line as the tail of the cone. (Or if you like, you can just continue the same polygon, making sure the opposite 'tail' is the same length as <spell range>. This lets you skip step 6 as Aaron observed below.)
6. Group the triangle with the short straight line. This will allow you to rotate the cone effect centered on the point of origin. If the point of origin have to be moved, you need to make the diagram group entirely horizontal or vertical again before moving it to a new point of origin and rotating it.
7. Rotate the cone to 'sweep' across the screen. Creatures are affected if a square they occupy is at least 50% covered by your spell effect.

I've noticed that on a lot of discussion topics about cones (here and elsewhere), people still linked those 'quarter circle' templates we used in 3.5e. Based on my reading of the PHB from both 3.5e and 5e editions, 5e cones have been 'flattened' at the end.

• 5e: "A cone's width at a given point is equal to that points distance from the point of origin." (I.e. the end is flat. The effect basically forms a triangle)
• 3.5e: "A cone shaped spell shoots away from you in a quarter-circle in the direction you designate." (I.e. the end is rounded.)

That's pretty clever. I hadn't considered the "tail".

That tail is very clever.  It lets you get the rotation you would normally need an image with a buttload of transparency for.  If you drew that all connected, you wouldn't need to drag-select or shift-select them to do the rotation.  Basically, draw a wine glass shape.

The Aaron said:

That tail is very clever.  It lets you get the rotation you would normally need an image with a buttload of transparency for.  If you drew that all connected, you wouldn't need to drag-select or shift-select them to do the rotation.  Basically, draw a wine glass shape.

Yeah haha. But I didn't like it for some reason. It looks to me like "throw a water baloon along this line, and it splats, producing a cone." Although that's probably pretty silly of me - no one would misunderstand it for that. But it just makes my eye twitch hahaha. But yeah - wine glass is less work.