Aframe create shape from vectors - three.js

Question

I'm doing something like this, How to create a custom square in a-frame but with custom shapes (i.e. drawing around an image to make a hotspot to make part of that image interactive)
I've got the line working and I'm now trying to convert this into a fill.
this._mesh = make('a-plane', {
geometry:"buffer: false"
}, this.el)
this._mesh.addEventListener('loaded', e => {
this._mesh.getObject3D('mesh').geometry.vertices = this._points
this._mesh.getObject3D('mesh').geometry.computeFaceNormals()
this._mesh.getObject3D('mesh').geometry.computeVertexNormals()
})
I'm getting close but it's only showing one triangle i.e. something like this
How do i get the shape to fill the whole area? I have done this before with a ConvexGeometry and Quick hull but it seems cumbersome.
I got the idea for updating the vertices of a plane from the above post.

Answer 1

If you create an array with Vector2 objects representing the contour of your shape in CCW order, you can use an instance of Shape and ShapeBufferGeometry to achieve the intended result. Just pass the array of points to the ctor of Shape. The following official three.js example demonstrates this approach:
https://threejs.org/examples/webgl_geometry_shapes
BTW: Instead of defining the contour by an array of points, you can also use the API of Shape to define shapes. A simple triangle would look like so:
var triangleShape = new THREE.Shape()
.moveTo( 80, 20 )
.lineTo( 40, 80 )
.lineTo( 120, 80 )
.lineTo( 80, 20 );
var geometry = new THREE.ShapeBufferGeometry( shape );
var mesh = new THREE.Mesh( geometry, material );
three.js R113