# Draw a circle in 3D space procedurally

So, lets say I have a base actor. I need to draw a line(in a circle) across the landscape. It would be prefered that this line were to adjust to height changes in the landscape. These lines will be created by players during runtime. I am sure there is a way to do this, I am unsure, however, of how to do it myself. Thanks for your time.

Given a center position and a radius, you can find any point on a circle:

``````X = r * cos(theta)
Y = r * sin(theta)
``````

just increment theta by the number of segments you want to have in your circle.

You’ll also want to use these X/Y values to create a ray which intersects with the landscape to grab the Z value. Use “Single Line Trace” for this.

Once you’ve got an array of 3D vectors for your circle plotted out, you can draw a line segment to connect each of the vertices together. Now you have a circle projected onto your landscape!

Ahh, yes, that’s perfect, thank you sir!

Works perfectly, thanks!

so how exactly do you draw each segment? THAT is the question… and don’t say debugline