Constraints in 3D Sketching
When sketching in 3D, you can snap to the major directions, X, Y, or Z, and constraints are applied Along X, Along Y, and Along Z, respectively. These are constraints to the global coordinate system.
When sketching on a plane, you can snap to the horizontal or vertical directions in the plane, and constraints are applied to the Horizontal and the Vertical. These are constraints to a plane, planar face, etc.
Planes
You can add planes while in a 3D sketch. 3D plane attributes include:
- Define. Planes can be fully defined, over defined and under defined.
- Relations. You can:
- Add or remove relations to planes.
- Use relations to position other geometry or to position the plane.
- Move. Move planes by dragging, resize planes by dragging the corner handles, and rotate planes using the center handles.
- Activate. Double-click to activate a plane.
When you use RapidSketch with any open sketch tool, a plane is created on any planar face that you select.
Display
In the Properties PropertyManager, you can hide dimensions, relations or planes.
When sketching in the 2D mode on a 3D plane, entities that are not on the active sketch plane are muted.
Relations and dimensions that do not involve the plane or segment on it are hidden.
Sketcher Triad
Use the Sketcher Triad 
to limit the drag of entities.