Fill curve node adding extra lines to object in geometry nodes

Question

I've created a yin yang symbol with the ability to change the number of "arms" in geometry nodes, see example below.

But when I use the Fill Curve node (to fill the faces of each arm) it adds various straight lines. See image below with arrows.

It should look something like this for three arms see image below.

I've tried Mesh to Curve and Curve to Mesh but the lines keep popping up.

See Blend file below.

Answer 1

(Using Blender 3.6.8)

Approach: build a single "leaf", then duplicate and rotate it.

To build the leaf:

To fill the leaf, then to duplicate it with rotation: The nodes sequence Join Geometry, Curve to Mesh, Merge by Distance and Mesh to Curve is providing a single closed curve.

Resources:

Answer 2

N-sided yin-yang

The idea is to build 3 curves (corresponding to each side of the shape) as follows :

• A half-circle as the first branch
• A half-circle as the second branch
• An arc as the outside of the shape

The geometry nodes are a bit heavy but I tried staying as simple as possible. I've reused the general process you were following but I've restarted from scratch.

My general process is : generate each part of the outline as curves, convert them to meshes so it's simpler to work with (basically join them), then at last convert them back to curves and fill them.

Additionnal informations

• Both 1st branch and 2nd branch are identical. The only difference is the input counter, which is increased by 1 for the second branch.
• Minimum number of surfaces is 2, like yin-yang (will break for 1)
• The resolution of the branches and outside parts must be high enough. Otherwise, you may have issues where the branches reach the outside circle.
• The Divide nodes have as input 2*pi (so 6.28). They give the amount of rotation (in rad) that should happend between two successive shapes.

Blend file

Showcase