//               Persistence of Vision Raytracer Version 3.5
//                           Screen Include File

// Created by Christoph Hormann, Chris Huff and Rune S. Johansen.

// Screen.inc will enable you to place objects and textures right in front
// of the camera. One use of this is to place your signature or a logo in
// the corner of the image.

// You can only use screen.inc with the perspective camera. Screen.inc
// will automatically create the camera definition for you when it is
// included.

// Note that even though objects aligned using screen.inc follow the
// camera, they are still part of the scene. That means that they will be
// affected by perspective, lighting, the surroundings etc.

// For instructions of use, look in the POV-Ray manual, and for an example
// of use, see screen.pov.


#ifndef(Screen_Inc_Temp)
#declare Screen_Inc_Temp = version;
#version 3.5;

#ifdef(View_POV_Include_Stack)
   #debug "including screen.inc\n"
#end

#macro Update_Camera()
   
   #ifndef (Camera_Aspect_Ratio)
      #declare Camera_Aspect_Ratio = image_width/image_height;
   #end
   #ifndef (Camera_Location) #declare Camera_Location = <0,0,0>; #end
   #ifndef (Camera_Look_At)  #declare Camera_Look_At = z;        #end
   #ifndef (Camera_Sky)      #declare Camera_Sky = y;            #end
   #ifndef (Camera_Zoom)     #declare Camera_Zoom = 1;           #end
   
   
   #declare CamL=Camera_Location;                     // wherever you're putting it
   #declare CamD=vnormalize(Camera_Look_At-CamL);     // direction of camera view
   #declare CamR=vnormalize(vcross(Camera_Sky,CamD)); // to the right
   #declare CamU=vnormalize(vcross(CamD,CamR));       // camera up
   #declare Camera_Transform =
   transform {
      matrix <
         CamR.x, CamR.y, CamR.z,
         CamU.x, CamU.y, CamU.z,
         CamD.x, CamD.y, CamD.z,
         CamL.x, CamL.y, CamL.z
      >
   }
   
   camera {
     direction CamD*Camera_Zoom
     right CamR*Camera_Aspect_Ratio
     up CamU
     sky Camera_Sky
     location CamL
   }
   
#end

Update_Camera()

#macro Set_Camera_Location(Loc)
   #declare Camera_Location = Loc;
   Update_Camera()
#end
#macro Set_Camera_Look_At(LookAt)
   #declare Camera_Look_At = LookAt;
   Update_Camera()
#end
#macro Set_Camera_Aspect_Ratio(Aspect)
   #declare Camera_Aspect_Ratio = Aspect;
   Update_Camera()
#end
#macro Set_Camera_Aspect(Width,Height)
   #declare Camera_Aspect_Ratio = Width/Height;
   Update_Camera()
#end
#macro Set_Camera_Sky(Sky)
   #declare Camera_Sky = Sky;
   Update_Camera()
#end
#macro Set_Camera_Zoom(Zoom)
   #declare Camera_Zoom = Zoom;
   Update_Camera()
#end
#macro Set_Camera_Angle(Angle)
   #declare Camera_Zoom = 0.5/tan(radians(Angle/2))*Camera_Aspect_Ratio;
   Update_Camera()
#end
#macro Set_Camera(Location, LookAt, Angle)
   #declare Camera_Location = Location;
   #declare Camera_Look_At = LookAt;
   Set_Camera_Angle(Angle)
   Update_Camera()
#end
#macro Reset_Camera()
   #undef Camera_Location
   #undef Camera_Aspect_Ratio
   #undef Camera_Location
   #undef Camera_Look_At
   #undef Camera_Sky
   #undef Camera_Zoom
   Update_Camera()
#end

#macro Screen_Object (Object, Position, Spacing, Confine, Scaling)
   #local Obj_Max = max_extent(Object);
   #local Obj_Min = min_extent(Object);
   #local Obj_Cen = (Obj_Max+Obj_Min)/2;
   #local Obj_Dim = (Obj_Max-Obj_Min)/2;
   #local Pos = (Position-0.5)*2;
   #local Pos = (
      +<Pos.x*Camera_Aspect_Ratio/2,Pos.y/2,Camera_Zoom>
      +( -Obj_Cen -Pos*(Obj_Dim+Spacing) ) * Confine
   );
   object {
      Object
      no_shadow     // shouldn't cast shadows in the scene
      no_reflection // shouldn't be reflected in scene elements
      translate Pos
      scale Scaling
      transform {Camera_Transform}
   }
#end

#macro Screen_Plane (Texture, Scaling, BLCorner, TRCorner)
   box {
      <-0.000001,-0.000001,0>, <+1.000001,+1.000001,0>
      texture {Texture}
      scale TRCorner*<1,1,0>-BLCorner*<1,1,0>+z
      translate BLCorner*<1,1,0>+<-0.5,-0.5,0>
      scale <Camera_Aspect_Ratio,1,1>
      no_shadow     // shouldn't cast shadows in the scene
      no_reflection // shouldn't be reflected in scene elements
      hollow on     // for media/fog
      translate Camera_Zoom*z
      scale Scaling
      transform {Camera_Transform}
   }
#end

#version Screen_Inc_Temp;
#end