Add Irregular object

CesiumJS
1

how to add a Irregular body if i know the face

2

how to create a mesh by the points in cesium

3

// First prepare position, normal, uv buffers.

let position = new Cesium.GeometryAttribute({
componentDatatype: Cesium.ComponentDatatype.DOUBLE,
componentsPerAttribute: 3,
values: new Float64Array(positionBuffer)
});

let normal = new Cesium.GeometryAttribute({
    componentDatatype: Cesium.ComponentDatatype.FLOAT,
    componentsPerAttribute: 3,
    values: new Float32Array(normalBufffer)
});

let st = new Cesium.GeometryAttribute({
    componentDatatype: Cesium.ComponentDatatype.FLOAT,
    componentsPerAttribute: 2,
    values: new Float32Array(uvBuffer)
});

// prepare material

let customPrimitive = new Cesium.Primitive({
    geometryInstances : new Cesium.GeometryInstance({
        geometry: new Cesium.Geometry({
            attributes: {
                position: position,
                normal: normal,
                st: st
            },
            indices : new Uint16Array(sphereGeometry.index),
            primitiveType: Cesium.PrimitiveType.TRIANGLES,
            boundingSphere: Cesium.BoundingSphere.fromVertices(positionBuffer)
        }),
    }),
    appearance: new Cesium.MaterialAppearance({
        material: material,
        closed: true
    }),
    asynchronous: false
});

viewer.scene.primitives.add(spherePrimitive);