Two ways to approach this:
1. Multimouse enabled (the hard way)
Multimouse treats each optical encoder as a separate device. (picture each device controlling it's own unique mouse pointer)
Each MAME input only recognizes the one device axis mapped to it.
For example, if the spinner is Mouse 2's X-axis and the trackball is Mouse 3, turning the spinner will not be seen by a MAME input mapped to Mouse 3's X-axis
If you unplug the USB cables, windows can (and often will) change the device number/order.
If you need to have multimouse enabled
and want to plug/unplug the USB cables without remapping the controls, look into DrVenture's excellent
ControllerRemap utility.
2. Multimouse not enabled (the easy way)
Windows adds the same-axis inputs from multiple (up to 8 IIRC) optical encoders to control just one mouse pointer.
For example, if you turn the spinner 4 transitions left (X-axis) and your arm accidently nudges the trackball 2 transitions right (X-axis) and 1 transition up (Y-axis), Windows will add the same-axis inputs together (X-axis: 4 left + 2 right = 2 left
and Y-axis: nothing + 1 up = 1 up) and that's what MAME will see. (2 left, 1 up)
Possible downsides to this approach are:
* The accidental nudge described above interferes with gameplay
(not likely if you arrange your controls properly on the panel
)
* You want to configure a spinner game for two player simultaneous play like Pong
(one player on spinner, the other on trackball will only work right with Multimouse enabled)
Scott