ArchiCAD’s Mouse Constraints are like having a computerized T-square and triangle available while drafting in the Floor Plan. They are editing aids that can be used as an alternative to Guide Lines, although most users will prefer to use Guide Lines in 2D windows.
See Guide Lines.
The angle pairs they define can be used to lock the cursor at a particular drawing angle, by pressing Shift during input. The mechanism can only be engaged while drawing or editing an element, as indicated by the thick rubber band line shown in the Floor Plan or the ghosted element contour shown in the 3D Window. It temporarily locks the cursor’s polar angle value in the Coordinates Palette using one of the angle pairs defined in the Options > Work Environment > Mouse Constraints and Methods.
See Mouse Constraints and Methods Dialog Box.
Three orthogonal angles/angle pairs can be specified:
•The horizontal-vertical set aligned to the main grid
•The horizontal-vertical set aligned to the rotated grid
•The fixed angle set
The fixed angle set can be set relative to the rotated grid or the main grid. A practical use for the fixed angle orthogonal set would be aligning multiple elements with a roadway. In addition, you can check one or both Guide Line constraint options:
•Nearest Instant Guide Line
•Lasting Guide Lines