Here is a Papervision3D demo using Zupko’s ShadowCaster class and a little tip to prevent the floor plane from hiding the objects :

viewport.containerSprite.sortMode = ViewportLayerSortMode.INDEX_SORT;
viewport.getChildLayer(floor,true).layerIndex = 1;
viewport.getChildLayer(objects,true).layerIndex = 2;

Click once to lift object’s layer up and once more to release it :
View the demo