--
-- File      :  PerspectiveView.cdl
-- Created   :  Wed 3 Feb 1993
-- Author    : CKY / Contract Toubro-Larsen ( Niraj RANGWALA )
--
---Copyright : MATRA-DATAVISION  1993
--

class PerspectiveView from IGESDraw  inherits ViewKindEntity

        ---Purpose: defines IGESPerspectiveView, Type <410> Form <1>
        --          in package IGESDraw
        --
        --          Supports a perspective view.
        --          Any geometric projection is defined by a view plane
        --          and the projectors that pass through the view plane.
        --          Projectors can be visualized as rays of light that
        --          form an image by passing through the viewed object
        --          and striking the view plane.
        --          The projectors are defined via a point called the
        --          Centre-of-Projection or the eye-point.
        --          A perspective view is formed by all projectors that
        --          emanate from the Centre-of-Projection and pass
        --          through the view plane.

uses

        TransfEntity            from IGESData,
        Vec                     from gp,
        XY                      from gp,
        XYZ                     from gp,
        Pnt2d                   from gp,
        Pnt                     from gp

raises OutOfRange

is

        Create returns mutable PerspectiveView;

        -- Specific Methods pertaining to the class

        Init (me                  : mutable;
              aViewNumber         : Integer;
              aScaleFactor        : Real;
              aViewNormalVector   : XYZ;
              aViewReferencePoint : XYZ;
              aCenterOfProjection : XYZ;
              aViewUpVector       : XYZ;
              aViewPlaneDistance  : Real;
              aTopLeft            : XY;
              aBottomRight        : XY;
              aDepthClip          : Integer;
              aBackPlaneDistance  : Real;
              aFrontPlaneDistance : Real);
        ---Purpose : This method is used to set the fields of the class
        --           PerspectiveView
        --       - aViewNumber         : The desired view
        --       - aScaleFactor        : Scale factor
        --       - aViewNormalVector   : View plane normal vector (model space)
        --       - aViewReferencePoint : View reference point     (model space)
        --       - aCenterOfProjection : Center Of Projection     (model space)
        --       - aViewUpVector       : View up vector           (model space)
        --       - aViewPlaneDistance  : View plane distance      (model space)
        --       - aTopLeft            : Top-left point of clipping window
        --       - aBottomRight        : Bottom-right point of clipping window
        --       - aDepthClip          : Depth clipping indicator
        --       - aBackPlaneDistance  : Distance of back clipping plane
        --       - aFrontPlaneDistance : Distance of front clipping plane

    	IsSingle (me) returns Boolean;
	---Purpose : Returns True (for a single view)

    	NbViews (me) returns Integer;
	---Purpose : Returns 1 (single view)

    	ViewItem (me; num : Integer) returns ViewKindEntity  raises OutOfRange;
	---Purpose : For a single view, returns <me> whatever <num>

        ViewNumber (me) returns Integer;
        ---Purpose : returns the view number associated with <me>

        ScaleFactor (me) returns Real;
        ---Purpose : returns the scale factor associated with <me>

        ViewNormalVector (me) returns Vec;
        ---Purpose : returns the View plane normal vector (model space)

        ViewReferencePoint (me) returns Pnt;
        ---Purpose : returns the View reference point (model space)

        CenterOfProjection (me) returns Pnt;
        ---Purpose : returns the Center Of Projection (model space)

        ViewUpVector (me) returns Vec;
        ---Purpose : returns the View up vector (model space)

        ViewPlaneDistance (me) returns Real;
        ---Purpose : returns the View plane distance (model space)

        TopLeft (me) returns Pnt2d;
        ---Purpose : returns the top left point of the clipping window

        BottomRight (me) returns Pnt2d;
        ---Purpose : returns the bottom right point of the clipping window

        DepthClip (me) returns Integer;
        ---Purpose : returns the Depth clipping indicator
        --     0 = No depth clipping
        --     1 = Back clipping plane ON
        --     2 = Front clipping plane ON
        --     3 = Back and front clipping planes ON

        BackPlaneDistance (me) returns Real;
        ---Purpose : returns the View coordinate denoting the location of
        -- the back clipping plane

        FrontPlaneDistance (me) returns Real;
        ---Purpose : returns the View coordinate denoting the location of
        -- the front clipping plane

        ViewMatrix (me) returns TransfEntity;
        ---Purpose : returns the Transformation Matrix

        ModelToView (me; coords : XYZ) returns XYZ;
        ---Purpose : returns XYX from the Model space to the View space by
        -- applying the View Matrix

fields

--
-- Class    : IGESDraw_PerspectiveView
--
-- Purpose  : Declaration of the variables specific to a
--            PerspectiveView Entity.
--
-- Reminder : A PerspectiveView Entity is defined by :
--                    -  The desired view
--                    -  Scale factor
--                    -  View plane normal vector (model space)
--                    -  View reference point (model space)
--                    -  Center Of Projection (model space)
--                    -  View up vector (model space)
--                    -  View plane distance (model space)
--                    -  Top-left point of clipping window
--                    -  Bottom-right point of clipping window
--                    -  Depth clipping indicator
--                         0 = No depth clipping
--                         1 = Back clipping plane ON
--                         2 = Front clipping plane ON
--                         3 = Back and front clipping planes ON
--                    -  Distance of back clipping plane
--                    -  Distance of front clipping plane
--

        theViewNumber           : Integer;

        theScaleFactor          : Real;

        theViewNormalVector     : XYZ;

        theViewReferencePoint   : XYZ;

        theCenterOfProjection   : XYZ;

        theViewUpVector         : XYZ;

        theViewPlaneDistance    : Real;

        theTopLeft              : XY;

        theBottomRight          : XY;

        theDepthClip            : Integer;

        theBackPlaneDistance    : Real;

        theFrontPlaneDistance   : Real;

end PerspectiveView;