anim3D/src/ConeGO.i3

 Copyright (C) 1993, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Created by Marc Najork                                                    
 Last modified on Sun Jun 12 15:47:31 PDT 1994 by najork                   




 A ConeGO.T is a geometric object describing a cone. 


INTERFACE ConeGO;

IMPORT GO, Point3, PointProp, RealProp, SurfaceGO;

TYPE
  T <: Public;
  Public = SurfaceGO.T OBJECT
  METHODS
    init (prec := 30) : T;
  END;

 cone.init(prec)  initializes a new cone cone, whose surface
   is composed of prec triangles, and returns it. The location and radius of
   the cone is determined by the three properties Base, Tip, and Radius.


VAR
  Base   : PointProp.Name;
  Tip    : PointProp.Name;
  Radius : RealProp.Name;

 In addition to the properties observed by all \type{GO}{T}'s and
   \type{SurfaceGO}{T}'s, there are three additional properties that
   are observed by ConeGO.T's:


   Base is the name of a property that describes the center of the base
   of the cone. It associates with a \type{PointProp}{Val}. If no Base
   property is specified, the base of the cone lies at the origin.


   Tip is the name of a property that describes the tip
   of the cone. It associates with a \type{PointProp}{Val}. If no Tip
   property is specified, the tip of the cone is at point (1,0,0).


   Radius is the name of a property that describes the radius of the
   cone. It associates with a \type{RealProp}{Val}. If no Radius property
   is specified, the cone has a radius of 1.


   Assume that in a given context and at a given point in time, the property
   mapping is such that Base maps to a point property value which
   evaluates to base, Tip maps to a point property value which evaluates
   to tip, and Radius maps to a real property value which evaluates to r.
   base, tip, and r define the position and shape of the cone in this c
   ontext and at this time as shown below:
   \begin{center}
   \begin{tabular}{c}
   \psfig{figure=images/ConeGO.ps,silent=}
   \end{tabular}
   \end{center}


PROCEDURE New (base, tip : Point3.T; r : REAL; prec := 30) : T;

 New(base,tip,r,prec) creates a new cone, whose surface is composed of
   prec triangles, and returns it. It also attaches the following properties
   to the new cone:
   \begin{verbatim}
     (Base,PointProp.NewConst(base))
     (Tip,PointProp.NewConst(tip))
     (Radius,RealProp.NewConst(r))
   \end{verbatim}

 The following three procedures provide sugaring to attach
   Base, Tip, and Radius properties with non-animated
   property values to geometric objects: 


PROCEDURE SetBase (o : GO.T; p : Point3.T);

 The expression SetBase(o,p) is equivalent to
   o.setProp(Base.bind(PointProp.NewConst(p))). 

PROCEDURE SetTip (o : GO.T; p : Point3.T);

 The expression SetTip(o,p) is equivalent to
   o.setProp(Tip.bind(PointProp.NewConst(p))). 

PROCEDURE SetRadius (o : GO.T; r : REAL);

 The expression SetRadius(o,r)is equivalent to
   o.setProp(Radius.bind(RealProp.NewConst(r))). 

END ConeGO.