-- File:	PerspectiveView.cdl
-- Created:	Tue Jan 21 15:28:48 1992
-- Author:	GG
-- Update:	             		
---Copyright:	Matra Datavision 1992


class PerspectiveView from V3d

    	---Purpose : Creates and modifies a perspective
	--           See the methods of the class View	



inherits View from V3d


uses

	Viewer from V3d,
	OrthographicView from V3d,
	PlaneAngle from Quantity

raises

        BadValue from Viewer
	
is

    	Create ( VM : mutable Viewer ) returns mutable PerspectiveView;
	---Level: Public
	---Purpose: Defines a perspective view in a viewer VM.
	--          The default angle of opening is given
	--          by the viewer.
     

    	Create ( VM : mutable Viewer ; V : OrthographicView )
					returns mutable PerspectiveView;  
	---Level: Public
	---Purpose: Creates a perspective view from the parameters 
	--	    of an orthographic view.
        --          The parameters of the original view are duplicated
        --          in the resulting view (Projection,Mapping,Context) .
        --          The view thus created must be activated in a new window.
	--          The default angle of opening is given
	--          by the viewer.



    	Create ( VM : mutable Viewer ; V : PerspectiveView ) 
					returns mutable PerspectiveView ; 
	---Level: Public
	---Purpose: Creates one perspective view from another.
        --          The parameters of the original view are duplicated
        --          in the resulting view (Projection,Mapping,Context) .
        --          The view thus created must be activated in a new window.

        Copy ( me ) returns mutable PerspectiveView from V3d is static;
	---Level: Public
	
        --------------------------------------------------------
        ---Category: Methods to modify the status of the view
        --------------------------------------------------------

    	SetAngle ( me : mutable ; Angle : PlaneAngle ) 
	---Level: Public
	---Purpose: Modifies the angle of opening of the perspective in RADIANS.
	--	    The projection window is resized according to the
	--	    formula :
	--	    TAN(Angle/2) = Size/Length       
	--	    	Size expresses the smallest dimension of the window.
    	--	        Length expresses the focal length.
	raises BadValue from Viewer 
	---Purpose:  Warning! raises BadValue from Viewer 
	--	    if the opening angle is <= 0 or >= PI 
        is static;
	
    	Angle ( me ) returns PlaneAngle  is static; 
	---Level: Public
	---Purpose: Returns the value of the angle of opening.

    	SetPerspective ( me : mutable ; Angle : PlaneAngle; 
		                 UVRatio, ZNear, ZFar : Real ) 
	---Level: Public
	---Purpose: Modifies the viewing perspective volume by given
	--		angle of opening of the perspective in RADIANS,
	--      aspect ratio of window width to its height and 
	--      near and far clipping planes
	raises BadValue from Viewer 
	--	    if the opening angle is <= 0 or >= PI or
    --      the ZNear<0, ZFar<0 or ZNear>=Zfar.
        is static;
	
end PerspectiveView;