10.1.4 Rotor Engines

Rotor engines rotate things. More exactly, they apply a rotation to whatever the current transformation is. They behave exactly like a Rotation transformation node except for the fact that the angle of the rotation changes continually over time, and they can be used wherever a Rotation node can be used in a scene graph. It is a very simple engine because you don't really need to connect anything to its fields in order for it to work.

The important fields are:

• rotation: the axis and initial angle of the rotation. The default value of "0 0 1 0" would represent a rotation about the Z axis. When you specify an axis of rotation for anything other than the Z axis, you must make the fourth value (the initial angle of rotation) non-zero in order for Open Inventor to correctly determine which axis you want to use.
• speed: the number of complete rotations per second. The default value is 1.
• on: a boolean switch that decides if the engine is currently running or not. The default value is TRUE.

Example

Here is a complete Inventor .iv file for an example that uses a Rotor engine node to make a cube rotate about the Y axis (note the non-zero value for the initial rotation) once every five seconds. Just cut and paste the text into a file named test.iv and then do ivview -q test.iv:

#Inventor V2.0 ascii

Separator {
    Rotor {
	rotation    0 1 0  0.1
	speed	    0.2
    }
    Cube {
    }
}

More Information

More information about Rotor engines is available in chapter 13 of Inventor Mentor and in the man page for SoRotor.