Rotating procedurally generated meshes

Question

I am creating voxel-based game (Minecraft etc.) and I was wondering how to rotate chunk parts that are more complex than simple squares, like the sides of a cube are.

For example, I created a staircase by manually constructing the mesh from code by giving the script the x,y,z coordinates of the virtual cube the staircase should appear in.

Now, how must I change the vertex coordinates of the staircase mesh so it gets rotated 90 degrees? Keep in mind that I can't just rotate the whole gameobject because the stairs would be part of a chunk's mesh.

Part of the code (creates vertices for one side of a very simple two-step staircase):

 List<Vector3> vertices = new List<Vector3>();
 
 
         int x = 4;
         int y = 0;
         int z = 3;
                 
             int angle = 0;//0 = 0 degrees, 1 = 90, and so on.
 
         vertices.Add(new Vector3(x, y, z));
         vertices.Add(new Vector3(x, y + 1, z));
         vertices.Add(new Vector3(x + 0.5f, y + 1, z));
         vertices.Add(new Vector3(x + 0.5f, y + 0.5f, z));
         vertices.Add(new Vector3(x + 1, y + 0.5f, z));
         vertices.Add(new Vector3(x + 1, y, z));

Answer 1

Best Answer

Answer by robertbu · Aug 06, 2014 at 06:04 PM

Untested on my part, but I think you can just do:

center - Vector3 around which you want to rotate the submesh
v - a vertex to rotate
q - a Quaternion representing the rotation you want to do

v = q * (v - center) + center;

So cycle through the vertex positions in the submesh you want to rotate, and apply the above to each one.

Add comment · Show 3 · Share

Cherno · Aug 06, 2014 at 10:36 PM 0

Share

You are, once again, my hero! It worked flawlessly, and it's far easier than my idea of somehow converting each vertex position while building the mesh :) A million thanks! Now I can fill my dungeon with all sorts of procedurally generated scenery without having to use hundres of gameObjects.

The center variable is, for my script, just (x + 0.5f, y, z + 0.5f).

omi670 · Feb 24, 2018 at 06:02 PM 0

Share

Hello, this worked great for me aswell, but I was wondering If you could explain the maths behind it, I feel like I am cheating if i dont know how it works. Thanks!

yourecrippled · Apr 14 at 10:13 AM 0

Share

    public Vector3 RotatePointAroundPivot(Vector3 point, Vector3 pivot, Vector3 angles)
         {
             return Quaternion.Euler(angles) * (point - pivot) + pivot;
         }

It's the code he explained.

Answer 2

Answer by BergOnTheJob · Jul 10, 2020 at 05:14 PM

If anyone is looking, this tool can rotate vertices of a mesh, and transform vertices using handle manipulation or directly entering the x,y,z coordinates of each vertex. https://assetstore.unity.com/packages/slug/166155

it also has a bunch of other tools to further model your staircase or any object's mesh.

Add comment · Share

Rotating procedurally generated meshes

2 Replies

Your answer

Follow this Question

Related Questions