MATLAB: How to Plot A 3D Ring of any given shape

Question

Say for example I have a 2D matrix that makes a simple shape like a star, rectangle or circle. How can I take this 2D shape and turn it into a 3D ring? If it was a star, a star shaped ring, if its a square, a square shaped ring and so on…

Answer 1

Create a reference set of vertices centered around 0, 0, and a description of faces joining them. I suggest using something compatible with patch()

Now translate the reference point out to what would correspond to angle 0 in the ring.

Now iterate.

Use makehgtform to create a transform matrix that would describe rotating (relative to the origin) by the appropriate angle for this iteration.

Now apply the transform matrix to the reference vertex coordinates by matrix multiplication, keeping them in the same relative order. Record the rotated coordinates for your point cloud. Usethe rotated coordinates and the previously constructed face information to patch() the rotated object into visual existence.

After all of the iterations, use the recorded vertices to patch() into place faces joining each rotated object to its adjacent rotated object -- the skin of the ring.

If your object being rotated has no internal structure such that the skin is all you care about then you can skip the patch() as you iterate, just using the list of final coordinates to build the skin.