The absolute (CTRL_ABSOLUTE) and relative (CTRL_RELATIVE) options are used by both Control::GetValue() and Control::SetValue() in a similar way.

• Control::GetValue()
• • CTRL_RELATIVE means that we're passing in a data structure which already contains a value and the controller is supposed to modify that value. In the case of position, rotation, scale, and TM controllers, this structure is a matrix. Note that not all controllers work in this way. A Lookat constraint, for example, ignores the incoming transform, because the desired world orientation is independent of the incoming orientation.
  • CTRL_ABSOLUTE indicates that we want the absolute value directly from the controller.
• CTRL_RELATIVE means that we're passing in a data structure which already contains a value and the controller is supposed to modify that value. In the case of position, rotation, scale, and TM controllers, this structure is a matrix. Note that not all controllers work in this way. A Lookat constraint, for example, ignores the incoming transform, because the desired world orientation is independent of the incoming orientation.
• CTRL_ABSOLUTE indicates that we want the absolute value directly from the controller.
• Control::SetValue()
• • CTRL_ABSOLUTE indicates that the given value should completely replace the current value in the controller.
  • CTRL_RELATIVE indicates that the given value should be 'added' to the current value. For data types which operate in a multiplicative space (rotation and scale) 'added' means 'multiply'.
• CTRL_ABSOLUTE indicates that the given value should completely replace the current value in the controller.
• CTRL_RELATIVE indicates that the given value should be 'added' to the current value. For data types which operate in a multiplicative space (rotation and scale) 'added' means 'multiply'.

In the example of a position controller, CTRL_RELATIVE indicates that the val pointer passed in points to a matrix. Typically the position controller would then pre-multiply in its translation however the controller could modify the matrix in other ways. For example the path controller overwrites the translation portion of the matrix instead of pre-multiplying.