Half-Space Specification (HCM 3-D)

3-D Standard > HCM > Tools > Half-space specification

Select 3-D Standard > HCM > Tools > Half-space specification. You use this function to supplement distance constraints for planes. The Change half-space spec. option can be found in the context menu of a distance constraint (right-click to open):

A plane divides three-dimensional space into two halves, the so-called half-spaces. If, for example, you want a point to have a fixed distance from this plane, it can accept the distance in one of these two halves.

The default setting here is that the half-space is "irrelevant", i.e. HCM 3-D attempts to retain the current state. Problems can arise if constraints are automatically defined by means of a macro or in connection with feature technology and, for example, a point has come to lie on the other side of the plane due to a previous transformation. In this case, the distance is also measured on this "other" side, which may mean that the result is not as desired. You can prevent this by defining a half-space specification in addition to the distance constraint.

1. You first need to define a constraint which allows a half-space specification. The default setting for the half space specification is always "...irrelevant".
2. In the Tools pull-down menu, select Change - Half-space specification.
3. Identify the constraint you want to change. A selection dialogue for the new half-space specification will be displayed.

4. You can now change the half-space specification.

When defining a distance between two planes, you can create a half-space specification for each of the two planes.

Example

In this drawing, a 15 mm distance of the cone to the cuboid surface has been defined by means of a distance constraint.

In the sketch, the currently used half-space is the complete space above the surface. The default setting for the half-space specification is "...irrelevant", i.e. HiCAD will attempt to leave the dimensional constraints in this half-space as they are (i.e. in this example, the 15 mm will always be measured upwards); however, this handling will not be forcibly applied. For instance, changes to other dimensional constraints can cause the dimension to be moved to the other half-space, to ensure a continued calculability of the HCM system:

This can be prevented by specifying that this dimension is always to be located in the positive half-space of the plane.

3-D Parts Constraint Manager • Distance