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Model Items

Some entities like 3D Labels or View Points are not purely geometric. Such entities are called Model Items

See also: View Points, Measurements.

Model items can be identified by its geometry type as obtained with IEntity_DG.GetGeometryType() or IGeometry_DG.GetGeometryType()

Localized Items

Localized Items are the Items, which also support Location property, managed by ILocation, Frame Type and Depth Position Type properties, managed by ILocationEx.

Possible Frame Type values are enumerated by EModelViewFrame. With Frame Type set to eModelViewFrameGlobal (default) the item is positioned relatively either the global frame of the model when the item is a top-level one or relative to the local frame of its parent. Coordinates of the item set via ILocation are normal Cartesian coordinates in the above frame.

When Frame Type is set to eModelViewFrameEye the item is positioned relatively either to the box of the Viewing Volume, when the item is a top-level one, or relative to the Bounding Box of the parent  object. The Bounding Box here is the minimal 3D box in Eye Frame containing the parent object. Coordinates of the item set via ILocation are normalized coordinates of the above box: For all coordinates range [-1,1] is mapped to dimension of the relevant box. Point (0,0,0) corresponds to the center of the box. Point (-1, -1, -1) is the left bottom back corner of the box. Point (1,1,1) is the right top front corner and (0.5, 0.5, 1) is the center of the front side of the box. Values outside the [-1,1] range are valid too and it is the common case. The item will be located outside the box in this situation.

Depth Position Type describes what additional, if any, positioning in z direction relative to the viewing plane (screen) is required. Depth Position Type values are enumerated by EModelEntity.

When Depth Position Type is eModelEntityUnknown (default) the depth is determined by coordinates of the item set via ILocation and no additional action is performed.

When Depth Position Type is eModelEntityObject the item will be translated in z direction to position it on the top of its parent object. In this case the item can be obscured by other objects in the model, but will always appear on the top of its parent.  If the item does not have a parent (top-level item) no z translation is performed.

When Depth Position Type is eModelEntityModel the item will be translated in z direction to position it on the top of all objects in the model, so it is never obscured.

See also: Entities, IItem, ILocationEx