SDL Library Documentation
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SDL_JoyBallEvent

Name

SDL_JoyBallEvent -- Joystick trackball motion event structure

Structure Definition

typedef struct{
  Uint8 type;
  Uint8 which;
  Uint8 ball;
  Sint16 xrel, yrel;
} SDL_JoyBallEvent;

Structure Data

typeSDL_JOYBALLMOTION
whichJoystick device index
ballJoystick trackball index
xrel, yrelThe relative motion in the X/Y direction

Description

SDL_JoyBallEvent is a member of the SDL_Event union and is used when an event of type SDL_JOYBALLMOTION is reported.

A SDL_JOYBALLMOTION event occurs when a user moves a trackball on the joystick. The field which is the index of the joystick that reported the event and ball is the index of the trackball (for a more detailed explaination see the Joystick section). Trackballs only return relative motion, this is the change in position on the ball since it was last polled (last cycle of the event loop) and it is stored in xrel and yrel.

See Also

SDL_Event, Joystick Functions, SDL_JoystickEventState, SDL_JoystickGetBall

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