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by Makoto Honda
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  User Guide
 Mouse Usage
 Function Mode
 Coordinate Key-in
 Current Plane
 New File
 Display Control
 File Manipulation


User Guide - Current Plane
Computer-Aided Design Software
(CAD System)

Computer-Aided Design Software

 G-System User Guide


6.  Current Plane  


The concept of the current plane is very important in a 3D CAD system.  The current plane provides “a frame of reference” in the user’s mind. The current plane is also a logical mechanism to map the cursor position (on the 2D screen or viewport surface) into the 3D coordinate in the 3D space.  That is, the current plane provide a bridge between a 2D cursor and the corresponding point in 3D space.  When the user clicks the viewport with the intent of specifying a 3D location (this user action is referred to as Indicate), the user is really clicking a point on the current plane.  The actual 3D coordinate perceived by the system, of course, depends on where the current plane is located and how it is oriented at the time of  the click. 

The current plane is sometimes referred to as “construction  plane” for a good reason.  In this CAD system also, the current plane is often used during the construction as well as manipulation of the geometric elements.  For instance, most of the 2D elements (flat elements)  are created on the current plane.  The mirror operation (see transformation) uses the current plane as the mirror plane.

The Grid Snap mode allows the snapping of grid intersections of the current plane, allowing a quick construction of the geometry.

Recognizing the importance of the current plane, this CAD system provides various functions to allow for the easy and intuitive manipulations of the current plane:  In addition to some preset orientations, the origin as well as orientation can be manipulated.  The current plane property dialog box allows various attribute settings including grid intervals and display characteristics.

Menu Structure

Current Plane
          Preset Planes
                    XY Plane / XZ Plane / YZ Plane / Toggle XYZ
                    Move Origin
                    Set Normal
                    On Element
                    True View
                    Rotate X,Y,Z / Rotate Toggle
          Named Current Plane…
          Grid Snap


 Preset Current Plane (XY / YZ / XZ)

Clicking this icon sets the current plane to one of the three preset orientations:  XY plane, YZ plane, and XZ plane.  Click this icon repeatedly to toggle through the three orientations.

 Move Origin

This FM allows the current plane origin to be moved to a user-defined location.  Define a point to become a new origin.

 Set Normal

This FM allows the current plane normal (thus its orientation) to be specified.  Define a point for the normal vector direction. A relative key-in allows the specification of the normal vector.

 Rotate XYZ

This FM allows current plane rotation about its X, Y, or Z axis.  Hit TOGGLE to alternate the rotation axes.  Hold down L-button and move to rotate.  An angle key-in is also allowed. CR (angle=0) is interpreted as 90 degrees. Defining a point moves the rotation axis to that point.  After a key-in, REPEAT repeats the same rotation angle.

 True View

The mode allows an arbitrary current plane specification.  The user is prompted to define three (3) points.  The first one becomes the origin, the second one defines the X axis, and the third to decide the Y axis.

 Snap On Element

This FM allows the current plane to be set as the same as the local coordinate of an element selected.  The user is prompted to select an element to snap on.


Current plane property dialog box…

 Grid Snap

This icon turns on the “grid snap” mode in which a specification of the coordinate by the mouse cursor is snapped to the nearest grid point of the current plane.  Unclick the icon to turn off this mode.


CAD System Web Site - Computer Aided Design Software:  Copyright © 2010-2013 Makoto Honda. All Rights Reserved.  

Copyright © 2010-2013 Makoto Honda. All Rights Reserved.