WireframeGeometry generates duplicate edges

WireframeGeometry generates duplicate edges for both indexed and non-indexed buffer geometry.

This is true by inspection, as the code does not test for duplicate xyz-coordinates.

A simple non-indexed example is:

const geometry = new THREE.TetrahedronGeometry( 1, 0 ); // 6 unique edges

const wireframe = new THREE.WireframeGeometry( geometry ); // 12 edges

BoxGeometry( 1, 1, 1 ) is a simple indexed example.

Duplicating an edge is not a problem most of the time, but when using dashed lines, it is a problem.

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EDIT: Actually, instead of “duplicate edges”, they should be referred to as “coincident edges”: A -> B = B -> A.

[WestLangley]

@Mugen87 Thanks for looking at this.

EdgesGeometry appears to work correctly. It uses a hardwired precision value and compares vertex coordinates.

TBH, I was surprised a threshold is used at all. In a well-formed geometry, there may be repeated vertices, but if the coordinates are not exactly equal, then, well, they are not repeat values.

[Mugen87]

but when using dashed lines, it is a problem.

Indeed, that does not look right: https://jsfiddle.net/dhq9zrx8/2/