geomobjs(3U)						    InterViews Reference Manual 					      geomobjs(3U)

NAME

       PointObj, LineObj, BoxObj, MultiLineObj, FillPolygonObj, Extent - helper classes that manage geometric information for structured graphics

SYNOPSIS

       #include <Unidraw/Graphic/geomobjs.h>

DESCRIPTION

       Unidraw	defines  several  helper  classes  that  store and manage geometric information.  Structured graphics objects may use these helper
       classes to support their semantics.  PointObj stores a point, LineObj stores two points, and MultiLineObj  stores  any  number  of  points.
       BoxObj  and FillPolygonObj define rectangular and polygonal areas, respectively.  Extent stores extent information, that is, the lower left
       corner and center of a bounding box plus a fixed amount of extra space around the bounding box.	All these classes provide  operations  for
       computing geometric information.

POINTOBJ PUBLIC OPERATIONS

       PointObj(Coord = 0, Coord = 0)
       PointObj(PointObj*)
	      Construct a PointObj, supplying either two Coords or another PointObj to specify the instance's coordinates, which are stored in its
	      _x and _y public members.

       float Distance(PointObj&)
	      Return the distance between this and the given PointObj.

LINEOBJ PUBLIC OPERATIONS

       LineObj(Coord = 0, Coord = 0, Coord = 0, Coord = 0)
       LineObj(LineObj*)
	      Construct a LineObj, supplying either two coordinate pairs or another LineObj to specify the instance's endpoints, which are  stored
	      in its _p1 and _p2 public members.

       boolean Contains(PointObj&)
       boolean Intersects(LineObj&)
	      Return whether this contains the given point and intersects the given line, respectively.

       int Same(PointObj& p1, PointObj& p2)
	      A helper function used in Intersects. Same returns a positive value if p1 and p2 fall on the same side of the line, 0 if both points
	      fall on the line, or a negative value if the points are on opposite sides of the line.

BOXOBJ PUBLIC OPERATIONS

       BoxObj(Coord = 0, Coord = 0, Coord = 0, Coord = 0)
       BoxObj(BoxObj*)
	      Construct a BoxObj, supplying either two coordinate pairs or another BoxObj to specify the instance's bottom-left and top-right cor-
	      ners, which are stored in its _left, _bottom, _right, and _top public members.

       boolean Contains(PointObj&)
       boolean Intersects(BoxObj&)
       boolean Intersects(LineObj&)
	      Return whether this contains the given point and intersects the given box or line, respectively.

       BoxObj operator - (BoxObj&)
       BoxObj operator + (BoxObj&)
	      Compute  the  intersection (-) or union (+) of this and the given box, returning the result.  These operations do not affect this or
	      their argument.

       boolean Within(BoxObj&)
	      Return true if this falls completely within the given box.  Within will also return true if the boxes are identical.

MULTILINEOBJ PUBLIC OPERATIONS

       MultiLineObj(Coord* = nil, Coord* = nil, int = 0)
	      Create a MultiLineObj, optionally supplying coordinate arrays (and their size) that define the vertices of the multiline. The Multi-
	      LineObj does not copy these arrays but stores them directly. The MultiLineObj stores this information in its _x, _y, and _count pub-
	      lic members.

       void GetBox(BoxObj&)
	      Calculate the bounding box circumscribing the MultiLineObj's vertices and store it in the argument.

       boolean Contains(PointObj&)
       boolean Intersects(BoxObj&)
       boolean Intersects(LineObj&)
	      Return whether this contains the given point and intersects the given box or line, respectively.

       boolean Within(BoxObj&)
	      Return true if this falls completely within the MultiLineObj's bounding box. Within will also return true if the boxes  are  identi-
	      cal.

       void SplineToMultiLine(Coord* cpx, Coord* cpy, int count)
       void ClosedSplineToMultiLine(Coord* cpx, Coord* cpy, int count)
	      Linearize  the  open  or	closed B-Spline defined by the given set of control points and store the result in this.  These operations
	      store the linearized result in internal buffers and assign the addresses of these buffers to _x and _y; they do not delete _x and _y
	      if they are non-nil prior to assignment.

MULTILINEOBJ PROTECTED OPERATIONS

       void GrowBuf()
	      Increase the size of the internal buffers used to store linearized splines.

       boolean CanApproxWithLine(
	   double x0, double, y0,
	   double x1, double y1,
	   double x2, double y2
       )
	      Return whether two connected line segments defined by the given three points can be approximated visually with a single line between
	      the endpoints.

       void AddLine(double x0, double y0, double x1, double y1)
	      Add a line to the internal buffer of vertices.

       void AddBezierArc(
	   double x0, double y0, double x1, double y1,
	   double x2, double y2, double x3, double y3
       )
	      Add lines approximating the appearance of a Bezier arc defined by the given points to the internal buffer of vertices.

       void CalcSection(
	   Coord cminus1x, Coord cminus1y, Coord cx, Coord cy,
	   Coord cplus1x, Coord cplus1y, Coord cplus2x, Coord cplus2y
       )
	      Add a Bezier arc to the internal buffer of vertices based on a series of four B-spline control points, the one before  and  the  two
	      after (cx, cy).

FILLPOLYGONOBJ PUBLIC OPERATIONS

       FillPolygonObj(Coord* = nil, Coord* = nil, int = 0)
	      Create  a  new  FillPolygonObj,  optionally  specifying its vertices.  If vertices are supplied, then the constructor uses Normalize
	      (described below) to store a normalized set of vertices in the FillPolygonObj's  _normx,	_normy,  and  _normCount  public  members.
	      FillPolygonObj is a subclass of MultiLineObj; thus it stores the constructor arguments in its _x, _y, and _count public members.

       virtual ~FillPolygonObj()
	      The destructor deletes the _normx and _normy arrays.

       boolean Contains(PointObj&)
       boolean Intersects(BoxObj&)
       boolean Intersects(LineObj&)
	      Return whether this contains the given point and intersects the given box or line, respectively.

FILLPOLYGONOBJ PROTECTED OPERATIONS

       void Normalize()
	      Copy  the  vertices defined by _x, _y, and _count into _normx, _normy, and _normCount such that (_normx[0], _normy[0]) is the lower-
	      leftmost vertex and there are no redundant vertices.

EXTENT PUBLIC OPERATIONS

       Extent(
	   float left = 0, float bottom = 0,
	   float cx = 0, float cy = 0, float tol = 0
       )

       Extent(Extent&)
	      Construct a new Extent, optionally supplying its parameters explicitly or providing a existing Extent to copy.  The  parameters  are
	      stored in the Extent's _left, _bottom, _cx, _cy, and _tol public members.

       boolean Undefined()
	      Return whether the extent is undefined, that is, if (_left, _bottom) and (_cx, _cy) are the same point.

       boolean Within(Extent&)
	      Return true if the given extent circumscribes this.  Within will also return true if the extents are identical.

       void Merge(Extent&)
	      Enlarge this extent to subsume area of the given extent.

SEE ALSO

       Graphic(3U)

Unidraw 							  2 February 1991						      geomobjs(3U)