The explicit calculation of visible edges has always existed in Bentley Descartes. However, in Bentley Descartes V8i (SELECTseries 3), the Cached Visible Edges option stores the edges for a drawing or sheet attachment in an intelligent cache that associates the edges with their underlying geometry. When an attachment is set to Cached, it performs a snapshot of the geometry when the cache was generated. The cached visible edges display will not change to reflect model changes until the cache is reloaded.

Although the cached visible edges display is static, in the sense that it does not dynamically reflect the state of the model, it is not disconnected from the model. If the source model is present, the cached visible edge display maintains its connection to that model. So selecting an element in a cached visible edge display works the same as the dynamic display and the element properties and links are available. If the underlying geometry is modified or deleted, the cached visible edges display reflects this state in the tooltip of the element that is modified or deleted.

Tooltip displaying that the original element is deleted

The cached visible edges cache displays the attachment even if the underlying 3D model is not present. In this case, the original element properties and links are not available, but otherwise the cache is displayed just as if the model were present. This makes it possible to distribute a cached drawing to a third party or a contractor without including the original 3D models.

You can set the cached visible edge setting from the References dialog’s Visible Edges list box column. You can also derive the Visible Edge setting from the drawing seed.

The Visible Edge setting works only for 3D models attached directly to 2D models. Specifically, you can create a cache for a 3D design model attached to a drawing model or a 3D design model directly attached to a sheet model.

The Cached Visible Edges Settings dialog also provides additional options that allow you to increase fidelity of dynamic views. It allows you to include calculated intersections, smooth out any faceted curves, and support custom line styles not supported in a dynamic view.

If you set the Visible Edge setting of a reference to Cached and if the reference is modified in the source model, the Visible Edges list box column in the References dialog turns red for that reference, indicating that the reference is modified and is out of date. The changes to the source model within the reference clip boundary or clip volume are only considered for indicating the change. You can then update the cache by reloading it.

The presence and status of cached visible edge references is also displayed by an icon in the status bar.

The cached visible edge references may require a long span of continuous processing time, this may turn Bentley Descartes into a "ghost", that is, the long processing time causes Windows OS to believe the task is unresponsive and it dims Bentley Descartes. This can be misleading and you may think Bentley Descartes is "hung", even though the process is proceeding. To disable this ghosting mechanism, you can set the configuration variable MS_DISABLEWINDOWGHOSTING to 1.