PerspectiveOffCenterFrustum - does it really work


I tried used PerspectiveOffCenterFrustum to create asymmetric perspective view, but it seems it does not work, so I tried to use PerspectiveOffCenterFrustum to create exactly the same frustum as PerspectiveView but Cesium either crashes the browser or the rendering stops. Here is my code in SandCastle

var viewer = new Cesium.Viewer(‘cesiumContainer’);

function createOffcenteFrustum(fovy, aspect, near, far) {

// it should create frustum equivalent to perpectiveview frustum

var top, bottom, left, right;
var frustum = new Cesium.PerspectiveOffCenterFrustum();

top = near * Math.tan(fovy/2);
bottom = -top;
right = top * aspect;
left = -right;

frustum.right = right;
frustum.left = left; = top;
frustum.bottom = bottom;
frustum.near = near;
frustum.far = far;  

return frustum;

} = createOffcenteFrustum(,,,

so my question is does PerspectiveOffCenterFrustum work ?