@Override
    public void getRandomPoint(Vector3f store) {
        int meshIndex = FastMath.nextRandomInt(0, vertices.size() - 1);
        // the index of the first vertex of a face (must be dividable by 3)
        int vertIndex = FastMath.nextRandomInt(0, vertices.get(meshIndex).size() / 3 - 1) * 3;
        // put the point somewhere between the first and the second vertex of a face
        float moveFactor = FastMath.nextRandomFloat();
        store.set(Vector3f.ZERO);
        store.addLocal(vertices.get(meshIndex).get(vertIndex));
        store.addLocal((vertices.get(meshIndex).get(vertIndex + 1).x - vertices.get(meshIndex).get(vertIndex).x) * moveFactor, (vertices.get(meshIndex).get(vertIndex + 1).y - vertices.get(meshIndex).get(vertIndex).y) * moveFactor, (vertices.get(meshIndex).get(vertIndex + 1).z - vertices.get(meshIndex).get(vertIndex).z) * moveFactor);
        // move the result towards the last face vertex
        moveFactor = FastMath.nextRandomFloat();
        store.addLocal((vertices.get(meshIndex).get(vertIndex + 2).x - store.x) * moveFactor, (vertices.get(meshIndex).get(vertIndex + 2).y - store.y) * moveFactor, (vertices.get(meshIndex).get(vertIndex + 2).z - store.z) * moveFactor);
    }
Randomly selects a point on a random face.

@param store
       storage for the coordinates of the selected point
jme3-core/src/main/java/com/jme3/effect/shapes/EmitterMeshFaceShape.java