{
   Copyright 2005-2012 Sandy Barbour and Ben Supnik
   
   All rights reserved.  See license.txt for usage.
   
   X-Plane SDK Version: 2.1.1                                                  
}

UNIT XPLMCamera;
INTERFACE
{
   XPLMCamera - THEORY OF OPERATION 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 later 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.                              
}

USES   XPLMDefs;
   {$A4}
{$IFDEF MSWINDOWS}
   {$DEFINE DELPHI}
{$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.        
   }
TYPE
   XPLMCameraControlDuration = (
     { Control the camera until the user picks a new view.                         }
      xplm_ControlCameraUntilViewChanges       = 1
 
     { Control the camera until your plugin is disabled or another plugin forcably }
     { takes control.                                                              }
     ,xplm_ControlCameraForever                = 2
 
   );
   PXPLMCameraControlDuration = ^XPLMCameraControlDuration;

   {
    XPLMCameraPosition_t
    
    This structure contains a full specification of the camera.  X, Y, and Z 
    are the camera's position in OpenGL coordiantes; 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).                                   
   }
   XPLMCameraPosition_t = RECORD
     x                        : single;
     y                        : single;
     z                        : single;
     pitch                    : single;
     heading                  : single;
     roll                     : single;
     zoom                     : single;
   END;
   PXPLMCameraPosition_t = ^XPLMCameraPosition_t;

   {
    XPLMCameraControl_f
    
    You use an XPLMCameraControl function to provide continuous control over 
    the camera.  You are passed in 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.           
   }
     XPLMCameraControl_f = FUNCTION(
                                    outCameraPosition   : PXPLMCameraPosition_t;    { Can be nil }
                                    inIsLosingControl   : integer;    
                                    inRefcon            : pointer) : integer; cdecl;   

   {
    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 key is pressed).                          
   }
   PROCEDURE XPLMControlCamera(
                                        inHowLong           : XPLMCameraControlDuration;    
                                        inControlFunc       : XPLMCameraControl_f;    
                                        inRefcon            : pointer);    
{$IFDEF DELPHI}
                                       cdecl; external 'XPLM.DLL';
{$ELSE}
                                       cdecl; external '';
{$ENDIF}

   {
    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.                                                    
   }
   PROCEDURE XPLMDontControlCamera;
{$IFDEF DELPHI}
                                       cdecl; external 'XPLM.DLL';
{$ELSE}
                                       cdecl; external '';
{$ENDIF}

   {
    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.                                  
   }
   FUNCTION XPLMIsCameraBeingControlled(
                                        outCameraControlDuration: PXPLMCameraControlDuration) : integer;    { Can be nil }
{$IFDEF DELPHI}
                                       cdecl; external 'XPLM.DLL';
{$ELSE}
                                       cdecl; external '';
{$ENDIF}

   {
    XPLMReadCameraPosition
    
    This function reads the current camera position.                            
   }
   PROCEDURE XPLMReadCameraPosition(
                                        outCameraPosition   : PXPLMCameraPosition_t);    
{$IFDEF DELPHI}
                                       cdecl; external 'XPLM.DLL';
{$ELSE}
                                       cdecl; external '';
{$ENDIF}

IMPLEMENTATION
END.
