-- File:	Poly_Connect.cdl
-- Created:	Mon Mar  6 15:16:16 1995
-- Author:	Laurent PAINNOT
--		<lpa@metrox>
---Copyright:	 Matra Datavision 1995


class Connect from Poly 

	---Purpose: 
    	-- Provides an algorithm to explore, inside a triangulation, the
    	-- adjacency data for a node or a triangle.
    	-- Adjacency data for a node consists of triangles which
    	-- contain the node.
    	-- Adjacency data for a triangle consists of:
    	-- -   the 3 adjacent triangles which share an edge of the triangle,
    	-- -   and the 3 nodes which are the other nodes of these adjacent triangles.
    	-- Example
    	-- Inside a triangulation, a triangle T
    	-- has nodes n1, n2 and n3.
    	-- It has adjacent triangles AT1, AT2 and AT3 where:
    	-- - AT1 shares the nodes n2 and n3,
    	-- - AT2 shares the nodes n3 and n1,
    	-- - AT3 shares the nodes n1 and n2.
    	-- It has adjacent nodes an1, an2 and an3 where:
    	-- - an1 is the third node of AT1,
    	-- - an2 is the third node of AT2,
    	-- - an3 is the third node of AT3.
    	-- So triangle AT1 is composed of nodes n2, n3 and an1.
    	-- There are two ways of using this algorithm.
    	-- -   From a given node you can look for one triangle that
    	--   passes through the node, then look for the triangles
    	--   adjacent to this triangle, then the adjacent nodes. You
    	--   can thus explore the triangulation step by step (functions
    	--   Triangle, Triangles and Nodes).
    	-- -   From a given node you can look for all the triangles
    	--   that pass through the node (iteration method, using the
    	--   functions Initialize, More, Next and Value).  
    	-- A Connect object can be seen as a tool which analyzes a
    	-- triangulation and translates it into a series of triangles. By
    	-- doing this, it provides an interface with other tools and
    	-- applications working on basic triangles, and which do not
    	-- work directly with a Poly_Triangulation.

uses

    Array1OfInteger from TColStd,
    Triangulation   from Poly

is

    Create (T : Triangulation from Poly) returns Connect from Poly;
	---Purpose: Constructs an algorithm to explore the adjacency data of
    	-- nodes or triangles for the triangulation T.
	
    Triangulation(me) returns Triangulation from Poly;
	---Purpose: Returns the triangulation analyzed by this tool.
	---C++: inline

    Triangle(me; N : Integer) returns Integer;
	---Purpose: Returns the index of a triangle containing the node at
    	-- index N in the nodes table specific to the triangulation analyzed by this tool
	---C++: inline

    Triangles(me; T: Integer; t1, t2, t3: out Integer);
    	---Purpose: Returns in t1, t2 and t3, the indices of the 3 triangles
    	-- adjacent to the triangle at index T in the triangles table
    	-- specific to the triangulation analyzed by this tool.
    	-- Warning
    	-- Null indices are returned when there are fewer than 3
    	-- adjacent triangles.

    Nodes(me; T: Integer; n1, n2, n3: out Integer);
    	---Purpose: Returns, in n1, n2 and n3, the indices of the 3 nodes
    	-- adjacent to the triangle referenced at index T in the
    	-- triangles table specific to the triangulation analyzed by this tool.
    	-- Warning
    	-- Null indices are returned when there are fewer than 3 adjacent nodes.
        
    Initialize(me: in out; N: Integer);
    	---Purpose: Initializes an iterator to search for all the triangles
    	-- containing the node referenced at index N in the nodes
    	-- table, for the triangulation analyzed by this tool.
    	-- The iterator is managed by the following functions:
  	-- -   More, which checks if there are still elements in the iterator
    	-- -   Next, which positions the iterator on the next element
    	-- -   Value, which returns the current element.
    	-- The use of such an iterator provides direct access to the
    	-- triangles around a particular node, i.e. it avoids iterating on
    	-- all the component triangles of a triangulation.
    	-- Example
    	-- Poly_Connect C(Tr);
    	-- for
    	-- (C.Initialize(n1);C.More();C.Next())
    	-- {
    	--        t = C.Value();
    	-- }

    More(me) returns Boolean;
	---Purpose: Returns true if there is another element in the iterator
    	-- defined with the function Initialize (i.e. if there is another
    	-- triangle containing the given node).
	---C++: inline


    Next(me: in out) 
	---Purpose: Advances the iterator defined with the function Initialize to
    	-- access the next triangle.
    	-- Note: There is no action if the iterator is empty (i.e. if the
    	-- function More returns false).-
    is static;


    Value(me) returns Integer;
    	---Purpose: Returns the index of the current triangle to which the
    	-- iterator, defined with the function Initialize, points. This is
    	-- an index in the triangles table specific to the triangulation
    	-- analyzed by this tool


fields

    myTriangulation : Triangulation from Poly;
    myTriangles : Array1OfInteger from TColStd;
    myAdjacents : Array1OfInteger from TColStd;
    mytr        : Integer from Standard;
    myfirst     : Integer from Standard;
    mynode      : Integer from Standard;
    myothernode : Integer from Standard;
    mysense     : Boolean from Standard;
    mymore      : Boolean from Standard;
    
end Connect;