anim3D/src/CylinderGO.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 Thu Jun  9 17:06:11 PDT 1994 by najork                   




 A CylinderGO.T is a geometric object describing a cylinder. 


INTERFACE CylinderGO;

IMPORT GO, Point3, PointProp, RealProp, SurfaceGO;

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

 cyl.init(prec)  initializes a new cylinder cyl, whose
   surface is composed of prec rectangles, and returns it.
   The location and radius of the cylinder is determined by the
   three properties Point1, Point2, and Radius. 

VAR
  Point1 : PointProp.Name;
  Point2 : 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 CylinderGO.T's:


   Point1 is the name of a property that describes the first endpoint
   of the cylinder. It associates with a \type{PointProp}{Val}. If no Point1
   property is specified, the cylinder starts at the origin.


   Point2 is the name of a property that describes the second endpoint
   of the cylinder. It associates with a \type{PointProp}{Val}. If no Point2
   property is specified, the cylinder ends at point (1,0,0).


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


   Assume that in a given context and at a given point in time, the property
   mapping is such that Point1 maps to a point property value which
   evaluates to p1, Point2 maps to a point property value which evaluates
   to p2, and Radius maps to a real property value which evaluates to r.
   p1, p2, and r define the position and shape of the cylinder
   in this context and at this time as shown below:
   \begin{center}
   \begin{tabular}{c}
   \psfig{figure=images/CylinderGO.ps,width=3in,silent=}
   \end{tabular}
   \end{center}


PROCEDURE New (p1, p2 : Point3.T; r : REAL; prec := 30) : T;

 New(p1,p2,r,prec)  creates a new cylinder, whose surface is composed
   of prec rectangles, and returns it. It also attaches the following
   properties to the new cylinder:
   \begin{verbatim}
     (Point1,PointProp.NewConst(p1))
     (Point2,PointProp.NewConst(p2))
     (Radius,RealProp.NewConst(r))
   \end{verbatim}

 The following three procedures provide sugaring to attach
   Point1, Point2, and Radius properties with non-animated
   property values to geometric objects: 


PROCEDURE SetPoint1 (o : GO.T; p : Point3.T);

 The expression SetPoint1(o,p) is equivalent to
   o.setProp(Point1.bind(PointProp.NewConst(p))). 

PROCEDURE SetPoint2 (o : GO.T; p : Point3.T);

 The expression SetPoint2(o,p) is equivalent to
   o.setProp(Point2.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 CylinderGO.