Rotation by Modifier

Automatic. The program’s amount of rotation arrows changes the amount of rotation a 1° at a time. Clicking on the rotate slider line changes rotation in increments of 5° – whether the rotation amount is increased or decreased depends on which side of the control key the click occurs:  down if clicked to the left and up if clicked on the right. Sometimes a fraction of the rotation is all that is needed. what are we to do? There are two methods: manual entry and a modifier.

Manual Method. The Rotate box allows an entry of any number. Like the zoom box entries, any decimal number entry becomes visually truncated, even though the decimal value of rotation is maintained. The rotation box will accept rotation values to 3 decimal points. That is, the smallest degree we can enter seems to be 0.001°.

Modifier-Based. When making a rotation change via a modifier, it is very important to realize that the method of measurement is very different than simply entering the number of degrees to rotate. Whereas the rotation box itself accepts the amount of rotation in degrees, the modifier accepts rotation amounts in the percent of a full rotation. A full rotation is represented by 360°.  When a layer has rotated from 0° to 360°, that represents 1 rotation.

  • Modifiers are composed of actions. In this case, the action is a Constant Amount. 1% of a rotation is represented as 1/100 = 0.01 = the Constant Amount. The action, once a value has been entered into the Constant Amount value box, is truncated to 2 decimal points. The rotation box accepts a manual value of 0.0001°, a modifier representation of this amount is 0.0001*100 = 0.01% or a constant value of 0.01. While it may be possible to enter a modifier constant of 0.0001 (for a rotation amount equal to 0.000001°), the rotation value is too small to see any change in rotation. Also, you are unlikely to see a value this small in the actions box since Constant Amount box values are rounded down to 2 decimal points in the actions list.
  • A Constant of:
    •    0.01 = 0.01%*360-degrees per 1 rotation/100% per rotation = 0.036°
    •    0.10 = 0.10%*360-degrees per 1 rotation/100% per rotation = 0.360°
    •    1.00 = 1.00%*360-degrees per 1 rotation/100% per rotation = 3.600°

Rotation Calculations. Generally we aren’t looking to rotate something a percent of a rotation, we are looking for a rotation in degrees. So, a little math is necessary to get the percent of rotation modifier Constant for the degrees of rotation desired. Therefore, multiply the degrees of rotation by 100%/rotation and divide it by 360 degrees/rotation. The following gives examples of the calculations for some values:

  • 0.5 degrees. 0.5*100÷360= 0.139% = 0.139
  • 10 degrees. 10*100÷360=2.778% = 2.778
  • 12.5 degrees. 12.5*100÷360= 3.472% = 3.472
  • 25 degrees. 25*100÷360= 6.944% = 6.944
  • 45 degrees. 45*100÷360=12.500% = 12.500
  • 90 degrees. 90*100÷360=25.000% = 25.000

© 20110417-1849 Dale Fenimore, All Rights Reserved

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