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Draft

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SDL_JoystickGetBall

Get the ball axis change since the last poll.

Syntax

int SDL_JoystickGetBall(SDL_Joystick *joystick,
                        int ball, int *dx, int *dy);

Function Parameters

joystick

the SDL_Joystick to query

ball

the ball index to query; ball indices start at index 0

dx

stores the difference in the x axis position since the last poll

dy

stores the difference in the y axis position since the last poll

Return Value

Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.

Remarks

Trackballs can only return relative motion since the last call to SDL_JoystickGetBall(), these motion deltas are placed into dx and dy.

Most joysticks do not have trackballs.

Code Examples

int delta_x, delta_y;
SDL_Joystick *joy;
.
.
.
SDL_JoystickUpdate();
if(SDL_JoystickGetBall(joy, 0, &delta_x, &delta_y)==-1)
  printf("TrackBall Read Error!\n");
printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);
SDL_JoystickNumBalls

CategoryAPI, CategoryJoystick, CategoryDraft


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