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 |
a pointer to the joystick to query |
ball |
the ball indices index; starts at index 0 |
dx |
the difference in the x axis since the last poll |
dy |
the difference in the y axis since the last poll |
Return Value
Returns 0 on success, or -1 if you passed it invalid parameters; call SDL_GetError() for more information.
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Code Examples
int delta_x, delta_y;
SDL_Joystick *joy;
.
.
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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
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Trackballs can only return relative motion since the last call to SDL_JoystickGetBall(), these motion deltas are placed into dx and dy.
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