Scale XYZ

The size of an object is thought of as its scale. When an object is created, its scale is automatically set to 1.0. The values related to scaling are called factors. The Scale command, available in all modules except Tools, lets you scale objects or points on objects interactively with the mouse or numerically in the Scaling dialogue box (see Changing Values).

An object is scaled from its own centre (local). For curves and points, scaling is applied from the global centre (origin). For example, a cube created at a length of 5 and scaled with a factor of 2 has a length of 10. A negative scaling yields an inverted object.

Scaling an Object

1. Select an object and choose the entire ScaleXYZ menu cell collection or one of its axis cells (ScaleX, ScaleY, or ScaleZ).
2. Select one of the Scaling modes (see Scaling Modes).
3. Choose a way to change the scaling values for the object as described in Changing Values.

Scaling Points

1. Select an object and choose Show->Point to display its points.
2. Activate the tagged point mode by selecting the TAG manipulation mode (see the Manipulation Modes section).
3. Tag the points you want to scale (press the t Supra key or refer to the Tag commands).
4. Choose the entire ScaleXYZ command or one of its axis cells (ScaleX, ScaleY, or ScaleZ).
5. Choose a way to change the scaling values for the points as described in Changing Values.

Note:

Note that transformations on points are additive only; clicking Set in the Scaling dialogue box has the same effect as Add.

Changing Values

You can change the values in the Scale menu cells using the mouse or the keyboard:

Using the Mouse

• Choose one of the three individual axis cells (ScaleX, ScaleY, or ScaleZ) for a scale to affect only that axis. This configures the mouse buttons so that when you drag the object or points, the:
  
  • Left mouse button applies a small increment on that axis.
  • Middle mouse button applies a medium increment.
  • Right mouse button applies a large increment.
    
• Click at the right edge (light grey area) of the Scale menu cells to activate the transformation for all three axes. This configures the mouse so that when you drag the object or points, the:
  
  • Left mouse button controls scaling in x.
  • Middle mouse button controls scaling in y.
  • Right mouse button controls scaling in z.

The mouse buttons can be used individually or simultaneously.

Using the Keyboard

• Choose one of the three axis menu cells and directly change the numbers in the text boxes in the menu cell. Doing this has the same effect as when you click Set in the Scaling dialogue box (described next).
• Click in the triangular tab in the upper-left corner of one of the axis menu cells to display the Scaling dialogue box in which you can set transformations numerically.
  
  Type the value in the corresponding text box and then click either Add or Set:
  
• Add increases or decreases the scaling by the value in the X, Y, Z text boxes. For example, if the default for X is 1, you change the value to 2 and click Add, 2 is added to the value of 1 so that the result is 3.

• Set sets the scaling to the value you specify in the X, Y, Z text boxes.

You can also use negative values, which are added or set accordingly.

Math Operations

The text boxes in the ScaleXYZ menu cells allow you to use the four basic math operations (addition, subtraction, multiplication, and division).

If you have the Multi menu cell selected, the math operation is added to each object's current values, which has the same effect as when you click Add in the Scaling dialogue box. For example, if two objects are selected (one with a scaling value of 45, the other with 90), the number in the Scale text box is displayed with a "d" at the beginning to show that the values for the two objects are different. If you add +45 to the end of the menu cell's value, the first model changes to 90 and the second to 135. This is different than if you specify 90 in the Scaling text box, which would make both objects have a scale of 90 units.

Note:

If you delete the number currently displayed and replace it with another, all objects are set to that value.

Scaling Modes

There are three scaling modes: Non-uniform (XYZ), Uniform (UNI), and Volumetric (VOL). All three can be used in conjunction with any of the manipulation modes (OBJ, TAG, CTR, TXT, or POL - see the Manipulation Modes section).

XYZ

The Non-uniform scaling mode is activated by default. You can also press Shift-F8 to activate it. This mode lets you scale an object by one of its three axes separately by using this mode.

The mouse movements are configured so that the left mouse button scales along the x-axis, the middle mouse button scales along the y-axis, and the right mouse button scales along the z-axis.

UNI

Uniform scaling mode allows you to scale uniformly along all three axes at once. You can also press Shift -F9 to activate this mode. This mode scales an object uniformly on all three axes so its shape does not change, just its size.

The left mouse button scales slowly, the middle mouse button scales at a moderate speed, and the right mouse button scales quickly.

VOL

Volumetric scaling mode allows you to scale an object along any axis while keeping the volume of its bounding box constant even though its proportions have changed. You can also press Shift-F10 to activate this mode. This mode is especially useful for "squashing" and "stretching" objects. For more information on volumetric scaling, see Preferences->Classic Scaling.

The left mouse button scales along the x-axis, the middle mouse button scales along the y-axis, and the right mouse button scales along the z-axis.

Last updated 02-apr-1998