DRAFT |
SDL_JoystickGetBall
Use this function to get the ball axis change since the last poll.
Contents
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 |
the difference in the x axis position since the last poll |
dy |
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.
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);
Remarks
Trackballs can only return relative motion since the last call to SDL_JoystickGetBall(), these motion deltas are placed into dx and dy.
