Maya Instancer

AimUpAxis: (vector)

This option specifies the object axis that points up relative to how the AimAxis points at the AimDirection or AimPosition. AimUpAxis is a vector attribute that works only with AimDirection and AimPosition rotation types. The default setting is None, which uses the value of <<0,1,0>> (positive Y-axis). If your object was built with the “nose” pointing down positive-X and its top facing positive-Y, you should never have to change this setting.

AimWorldAxis: (vector)

This option sets, in world coordinates, the axis that indicates the up direction used by the AimUpAxis. It’s a vector attribute that works only with AimDirection and AimPosition rotation types. The default setting is None, which uses the value of <<0,1,0 >> (positive Y-axis). This attribute is unaffected by the setting for the World Coordinate System's Up Axis found in the Window > Settings/Preferences > Preferences > Settings window. Again, if your object was built with the “nose” pointing down positive-X and its top facing positive-Y, you should never have to change this setting.

CycleStartObject: (float)

If you set the Cycle option of the Instancer to Sequence, CycleStartObject specifies the cycle's starting object from the Instanced Objects list. The default value is None, which will result in object 0 so your cycle would go 0-1-2-3… and cycle back to repeat from 0 when it reaches the end of the list.

However, this will result in all of your instanced objects starting with the same object and cycling at the same rate. So if you had a flock of 20 birds they would all be flapping their wings at the same rate and all their wings will be up, or down at the same time. For something like this you can create a custom float attribute called custom_start with the following expression: particleShape.custom_start = rand(20); Then map this attribute to CycleStartObject and you will have a flock of birds flapping their wings at the same speed, but some wings will be up, some will be down, and some will be in between, giving your animation a more natural look to it.