Positioning of 3D Labels
3D Labels have
ViewFrameType and DepthPositionType properties, managed by ILabel_DG.
Possible Frame Type values are enumerated by
ViewFrame_DG. With Frame Type
set to ViewFrame_DG.Global (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
ILabel_DG.Location
are normal Cartesian coordinates in the above frame.
When Frame Type is set to ViewFrame_DG.Eye 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
ILabel_DG.Location
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 label will
be located outside the box in this situation.
DepthPositionType describes what
additional, if any, positioning in z direction relative to the viewing plane
(screen) is required. Depth Position Type values are enumerated by
ModelEntity_DG.
WhenDepthPosition Type is ModelEntity_DG.Unknown (default) the depth is
determined by coordinates of the item set via ILabel_DG.Location
and no additional action is performed.
When DepthPositionType is ModelEntity_DG.Object 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 ModelEntity_DG.Model 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: NOSUPPORTV60 LabelEx Sample,
Entities, NOSUPPORTV60 Labels,
Items
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