SDL3/SDL_PenAxis

typedef enum SDL_PenAxis
{
    SDL_PEN_AXIS_PRESSURE = 0,               /**< Pen pressure.  Unidirectional: 0..1.0 */
    SDL_PEN_AXIS_XTILT,                      /**< Pen horizontal tilt angle.  Bidirectional: -90.0..90.0 (left-to-right).
                                                  The physical max/min tilt may be smaller than -90.0 / 90.0, cf. SDL_PenCapabilityInfo */
    SDL_PEN_AXIS_YTILT,                      /**< Pen vertical tilt angle.  Bidirectional: -90.0..90.0 (top-to-down).
                                                  The physical max/min tilt may be smaller than -90.0 / 90.0, cf. SDL_PenCapabilityInfo */
    SDL_PEN_AXIS_DISTANCE,                   /**< Pen distance to drawing surface.  Unidirectional: 0.0..1.0 */
    SDL_PEN_AXIS_ROTATION,                   /**< Pen barrel rotation.  Bidirectional: -180..179.9 (clockwise, 0 is facing up, -180.0 is facing down). */
    SDL_PEN_AXIS_SLIDER,                     /**< Pen finger wheel or slider (e.g., Airbrush Pen).  Unidirectional: 0..1.0 */
    SDL_PEN_NUM_AXES,                        /**< Last valid axis index */
    SDL_PEN_AXIS_LAST = SDL_PEN_NUM_AXES - 1 /**< Last axis index plus 1 */
} SDL_PenAxis;

Remarks

Below are the valid indices to the "axis" array from SDL_PenMotionEvent and SDL_PenButtonEvent. The axis indices form a contiguous range of ints from 0 to SDL_PEN_AXIS_LAST, inclusive. All "axis[]" entries are either normalised to 0..1 or report a (positive or negative) angle in degrees, with 0.0 representing the centre. Not all pens/backends support all axes: unsupported entries are always "0.0f".

To convert angles for tilt and rotation into vector representation, use SDL_sinf on the XTILT, YTILT, or ROTATION component, for example:

(This is the documentation for SDL3, which is under heavy development and the API is changing! SDL2 is the current stable version!)

SDL_PenAxis

Header File

Syntax

Remarks

Version