#ifndef _XPLMCamera_h_
#define _XPLMCamera_h_

/***************************************************************************
 * XPLMCamera
 ***************************************************************************/
/*
 * The XPLMCamera APIs allow plug-ins to control the camera angle in X-Plane.
 * This has a number of applications, including but not limited to:
 *
 * - Creating new views (including dynamic/user-controllable views) for the
 *   user.
 * - Creating applications that use X-Plane as a renderer of scenery,
 *   aircrafts, or both.
 *
 * The camera is controlled via six parameters: a location in OpenGL
 * coordinates and pitch, roll and yaw, similar to an airplane's position.
 * OpenGL coordinate info is described in detail in the XPLMGraphics
 * documentation; generally you should use the XPLMGraphics routines to
 * convert from world to local coordinates. The camera's orientation starts
 * facing level with the ground directly up the negative-Z axis (approximately
 * north) with the horizon horizontal. It is then rotated clockwise for yaw,
 * pitched up for positive pitch, and rolled clockwise around the vector it is
 * looking along for roll.
 *
 * You control the camera either either until the user selects a new view or
 * permanently (the latter being similar to how UDP camera control works). You
 * control the camera by registering a callback per frame from which you
 * calculate the new camera positions. This guarantees smooth camera motion.
 *
 * Use the XPLMDataAccess APIs to get information like the position of the
 * aircraft, etc. for complex camera positioning.
 *
 * Note: if your goal is to move the virtual pilot in the cockpit, this API is
 * not needed; simply update the datarefs for the pilot's head position.
 *
 * For custom exterior cameras, set the camera's mode to an external view
 * first to get correct sound and 2-d panel behavior.
 *
 */

#include "XPLMDefs.h"

#ifdef __cplusplus
extern "C" {
#endif

/***************************************************************************
 * CAMERA CONTROL
 ***************************************************************************/

/*
 * XPLMCameraControlDuration
 *
 * This enumeration states how long you want to retain control of the camera.
 * You can retain it indefinitely or until the user selects a new view.
 *
 */
XPLM_MAYBE_TYPEDEF enum XPLM_ENUM {
    /* Control the camera until the user picks a new view. */
    xplm_ControlCameraUntilViewChanges = 1,

    /* Control the camera until your plugin is disabled or another plugin
     * forcibly* takes control. */
    xplm_ControlCameraForever = 2,

} XPLM_ENUM_NAME(XPLMCameraControlDuration);
XPLM_ENUM_C(XPLMCameraControlDuration)

/*
 * XPLMCameraPosition_t
 *
 * This structure contains a full specification of the camera. X, Y, and Z are
 * the camera's position in OpenGL coordinates; pitch, roll, and yaw are
 * rotations from a camera facing flat north in degrees. Positive pitch means
 * nose up, positive roll means roll right, and positive yaw means yaw right,
 * all in degrees. Zoom is a zoom factor, with 1.0 meaning normal zoom and 2.0
 * magnifying by 2x (objects appear larger).
 *
 */
typedef struct {
    float x;
    float y;
    float z;
    float pitch;
    float heading;
    float roll;
    float zoom;
} XPLMCameraPosition_t;

/*
 * XPLMCameraControl_f
 *
 * You use an XPLMCameraControl function to provide continuous control over
 * the camera. You are passed a structure in which to put the new camera
 * position; modify it and return 1 to reposition the camera. Return 0 to
 * surrender control of the camera; camera control will be handled by X-Plane
 * on this draw loop. The contents of the structure as you are called are
 * undefined.
 *
 * If X-Plane is taking camera control away from you, this function will be
 * called with inIsLosingControl set to 1 and ioCameraPosition NULL.
 *
 */
typedef int (*XPLMCameraControl_f)(
    XPLMCameraPosition_t *outCameraPosition, /* Can be NULL */
    int inIsLosingControl, void *inRefcon);

/*
 * XPLMControlCamera
 *
 * This function repositions the camera on the next drawing cycle. You must
 * pass a non-null control function. Specify in inHowLong how long you'd like
 * control (indefinitely or until a new view mode is set by the user).
 *
 */
XPLM_API void XPLMControlCamera(XPLMCameraControlDuration inHowLong,
                                XPLMCameraControl_f inControlFunc,
                                void *inRefcon);

/*
 * XPLMDontControlCamera
 *
 * This function stops you from controlling the camera. If you have a camera
 * control function, it will not be called with an inIsLosingControl flag.
 * X-Plane will control the camera on the next cycle.
 *
 * For maximum compatibility you should not use this routine unless you are in
 * posession of the camera.
 *
 */
XPLM_API void XPLMDontControlCamera(void);

/*
 * XPLMIsCameraBeingControlled
 *
 * This routine returns 1 if the camera is being controlled, zero if it is
 * not. If it is and you pass in a pointer to a camera control duration, the
 * current control duration will be returned.
 *
 */
XPLM_API int XPLMIsCameraBeingControlled(
    XPLMCameraControlDuration *outCameraControlDuration); /* Can be NULL */

/*
 * XPLMReadCameraPosition
 *
 * This function reads the current camera position.
 *
 */
XPLM_API void XPLMReadCameraPosition(XPLMCameraPosition_t *outCameraPosition);

#ifdef __cplusplus
}
#endif

#endif