Get the number of trackballs on a joystick.
int SDL_JoystickNumBalls(SDL_Joystick *joystick);
|joystick||an SDL_Joystick structure containing joystick information|
Returns the number of trackballs on success or a negative error code on failure; call SDL_GetError() for more information.
Joystick trackballs have only relative motion events associated with them and their state cannot be polled.
Most joysticks do not have trackballs.
This function is available since SDL 2.0.0.