INTERFACE GraphicsBasePrivate;

IMPORT BSphere, Color, GO, LineTypeProp, MarkerTypeProp, Matrix4, Point,
       Point3, PropPrivate, ProxiedObj, RasterModeProp, RootGO, ShadingProp;

FROM GraphicsBase IMPORT T;

CONST
  VoidColor = Color.T {-1.0, -1.0, -1.0};

REVEAL T <: Private;

TYPE
  Private = ProxiedObj.T BRANDED OBJECT
    root   : RootGO.T := NIL;
    status : Status   := Status.Unmapped;
    stacks : REF ARRAY OF PropPrivate.Stack;
  METHODS
    unmap ();
    processEvents ();
    repair (VAR damaged : BOOLEAN);

    (*** Pushing and popping property lists onto the state **)
    push (caller : GO.T);
    pop (caller : GO.T);

    (*** Display Lists ***)
    openDisplayList (go : GO.T);
    closeDisplayList ();
    callDisplayList (go : GO.T);
    freeDisplayList (go : GO.T);

    (*** The matrix stack ***)
    pushMatrix (READONLY matrix : Matrix4.T);
    popMatrix ();

    (* Bounding volumes *)
    resetBoundingVolume ();
    growBoundingVolume (center : Point3.T; radius : REAL);
    getBoundingVolume () : BSphere.T;

    (* Camera control - setting viewing and projection transformations, and
       mapping points from screen coordinate space to world coordinate space *)
    setLookAt (from, to, up: Point3.T);
    setPerspProj (fovy, aspect: REAL);
    setOrthoProj (height, aspect: REAL);
    setupCamera ();
    screenToWorld (pos: Point.T; z: REAL): Point3.T;

    (*** Graphics Commands ***)
    setBackgroundColor (color : Color.T);
    setDepthcueing (switch: BOOLEAN;
                    frontPlane, backPlane, frontScale, backScale: REAL;
                    color: Color.T);

    setMarkerColor (val : Color.T);
    setMarkerScale (val : REAL);
    setMarkerType  (val : MarkerTypeProp.Kind);

    setLineColor (val : Color.T);
    setLineWidth (val : REAL);
    setLineType  (val : LineTypeProp.Kind);

    setSurfaceColor (val : Color.T);
    setSurfaceBackColor (val : Color.T);
       (* setting the back color to "VoidColor" indicates that it shall
          be the same as the front color *)
    setRasterMode (val : RasterModeProp.Kind);
    setDistinguishFacetsFlag (val : BOOLEAN);
    setLighting (val : BOOLEAN);
    setShading (val : ShadingProp.Kind);
    setSurfaceEdgeFlag (val : BOOLEAN);
    setSurfaceEdgeColor (val : Color.T);
    setSurfaceEdgeType (val : LineTypeProp.Kind);
    setSurfaceEdgeWidth (val : REAL);

    setAmbientReflCoeff (val : REAL);
    setDiffuseReflCoeff (val : REAL);
    setSpecularReflCoeff (val : REAL);
    setSpecularReflConc (val : REAL);
    setSpecularReflColor (val : Color.T);
    setTransmissionCoeff (val : REAL);

    addAmbientLight (color: Color.T);
    addVectorLight  (color: Color.T; dir: Point3.T);
    addPointLight (color: Color.T; point: Point3.T; att0, att1: REAL);
    addSpotLight (color: Color.T; point, dir: Point3.T;
                  conc, spread, att0, att1: REAL);

    drawMarker (p : Point3.T);
    drawLine (p1, p2 : Point3.T);
    drawPolygon (READONLY pts : ARRAY OF Point3.T; shape : GO.Shape);
    drawQuadMesh (READONLY pts : ARRAY OF ARRAY OF Point3.T; shape : GO.Shape);
    drawColoredQuadMesh (READONLY points: ARRAY OF ARRAY OF Point3.T;
                         READONLY colors: ARRAY OF ARRAY OF Color.T;
                                  shape : GO.Shape);

    drawProtoSphere (prec : INTEGER);
    drawProtoCone (prec : INTEGER);
    drawProtoCylinder (prec : INTEGER);
    drawProtoDisk (prec : INTEGER);
    drawProtoTorus (prec: INTEGER; radiusRatio : REAL);
  END;

Nodes can be damaged in two ways: \begin{enumerate} \item By operations that change the scene DAG (i.e.\ the group operations add, remove, and flush). \item By changes in the value of an attached property. \end{enumerate}

Calling root.adjust(time) serves two purposes: It reevaluates all the properties attached to all descendants of root, and damages those nodes whose properties have changed since the last round of rendering. It also propagates damages up the scene DAGs. base.repair(damaged) is called after all roots have been adjusted. The VAR parameter damaged is set to TRUE if there were any damages in the scene, otherwise, it remains unchanged.

TYPE Status = {Unmapped, Mapped, Destroyed};

END GraphicsBasePrivate.