Documentation of 'jvx.geom.PwGeodesic' Java class
PwGeodesic ("JavaView Reference Manual")
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"JavaView? v5.03.003"
jvx.geom

Class PwGeodesic

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, PsUpdateIf, PjWorkshopIf, PvPickListenerIf

    public class PwGeodesic
extends PjWorkshop
implements PvPickListenerIf
    Workshop for the computation of shortest and straightest geodesics that connect two given points on an element set. Can be used as numerics library if only static method getShortest(...) is used, or as a workshop by creating an instance of PwGeodesic and registering a geometry and a display. Pick events will be caught in the second case and the curve automatically computed. You can access the computed curve by method getPolygon(). After use as a workshop you need to call close() to tidy things up!
    See Also:
    Serialized Form
    Author:
    Eike Preuß
    Version:
    13.12.13, 3.60 revised (kp) Internal variable m_disp removed, superclass m_display used instead.
    17.10.13, 3.50 revised (fr) Add functionality of homotopic geodesic.
    01.03.06, 3.40 revised (ah) Use PnStraightestGeodesic.
    06.05.04, 3.30 revised (ep) Complete rewrite of getShortest method. Problems with boundary, loops and vertices as start or end coordinates should are solved.
    26.04.04, 3.20 revised (ep) Different methods for construction of triangle run for shortest method.
    03.07.03, 3.10 revised (ep) Made showWay() public.
    19.06.03, 3.00 revised (ep) Removed bug in 2d that miscalculated the angle of shortest geodesics.
    18.12.02, 2.90 revised (ep) Turn on edges.
    06.02.02, 2.80 revised (ep) New label for measured length, don't reduce max. length at boundary, update geodesic at setGeometry.
    24.01.02, 2.70 revised (ep) Removed bugs that appeared with new workshop handling.
    23.01.02, 2.60 revised (ep) Internationalization.
    29.12.01, 2.50 revised (kp) Minor revision of updates when using new workshop handling.
    19.09.01, 2.30 revised (ep) New cancel/ok behaviour.
    30.08.01, 2.20 revised (ep) Added various methods.
    26.07.01, 2.10 revised (ep) Bug removed ('listener already used').
    16.02.01, 2.00 revised (ep) Added functionality of straightest geodesics.

    • Field Detail

      • SHORTEST

        public static final int SHORTEST
        Method is set to this if pick events shall result in computation of shortest geodesics.
        See Also:
        Constant Field Values

      • STRAIGHTEST

        public static final int STRAIGHTEST
        Method is set to this if pick events shall result in computation straightest geodesics.
        See Also:
        Constant Field Values

      • SHORTEST_DIJKSTRA

        public static final int SHORTEST_DIJKSTRA
        Initial triangle run for SHORTEST is selected by smallest face-dijkstra distance.
        See Also:
        Constant Field Values

      • SHORTEST_DIJKSTRA_REUSE

        public static final int SHORTEST_DIJKSTRA_REUSE
        Initial triangle run for SHORTEST is selected by smallest face-dijkstra distance if new end/start face is not neighbouring old end/start face.
        See Also:
        Constant Field Values

      • SHORTEST_EUCL_DIJKSTRA

        public static final int SHORTEST_EUCL_DIJKSTRA
        Initial triangle run for SHORTEST is selected by smallest Euclidean face-dijkstra distance.
        See Also:
        Constant Field Values

      • SHORTEST_ELEMENT_TREE

        public static final int SHORTEST_ELEMENT_TREE
        Initial triangle run for SHORTEST is selected by smallest face-dijkstra distance.
        See Also:
        Constant Field Values

      • SHORTEST_DIJKSTRA_HOMOTOPIC

        public static final int SHORTEST_DIJKSTRA_HOMOTOPIC
        Initial triangle run for SHORTEST is selected from the previous triangle run and extended to the next coordinate point
        See Also:
        Constant Field Values

    • Constructor Detail

      • PwGeodesic

        public PwGeodesic()

    • Method Detail

      • init

        public void init()
        Sets the default length, angle and method. Does not remove the settings for the geometry or display.
        Overrides:
        init in class PjWorkshop

      • showWay

        public void showWay()
        Deprecated. Use computeWay() instead.
        Initiates re-calculation of geodesic and shows the result in the given display.

      • computeWay

        public void computeWay()
        Initiates re-calculation of geodesic. You need to call update(this) to make things visible.

      • setGeometry

        public void setGeometry(PgElementSet elemset)
        Geodesics are computed on the given surface. Sets starting element and endelement to default values that fit the geometry.

        Triangulates the geometry and removes degenerated faces if necessary.
        Call computeWay() to compute default geodesic.

        Parameters:
        elemset - Is triangulated if necessary. cancel() returns element set to non-triangulated state in this case.
        Version:
        14.10.06, 1.20 revised (kp) Computing element normals when missing or disabled.
        16.04.04, 1.10 revised (ep) Triangulates geometry if necessary.

      • removeGeometry

        public void removeGeometry()
        Description copied from class: PjWorkshop
        Remove the assigned geometry and its backup clone. Subclasses frequently overwrite this method but are advised to call this method.
        Overrides:
        removeGeometry in class PjWorkshop

      • getActualLength

        public double getActualLength()
        The current actual length of the computed geodesic.
        Returns:
        -1 if no geodesic is visible

      • setDisplay

        public void setDisplay(PvDisplayIf disp)
        Sets the display where the resulting geodesic shall be shown. Pick events are caught from this display also.
        Specified by:
        setDisplay in interface PjWorkshopIf
        Overrides:
        setDisplay in class PjWorkshop
        Parameters:
        disp - may be null - then the geodesic is not shown anywhere (default)

      • close

        public void close()
        Has to be called to remove workshop from element set as update listener and to remove polygon from display.
        Overrides:
        close in class PjWorkshop

      • cancel

        public void cancel()
        Cancels and closes the workshop (removing the computed geodesic from display).
        Overrides:
        cancel in class PjWorkshop

      • ok

        public void ok()
        Description copied from class: PjWorkshop
        Accept current version of the geometry as new version. Close workshop. The copy of the original geometry is ignored.

        Implementation in this class calls close().

        Overrides:
        ok in class PjWorkshop

      • getPolygon

        public PgPolygon getPolygon()
        The computed geodesic as an independent n-dimensional polygon. Is always the same instance of PgPolygon.
        Returns:
        computed geodesic as polygon.

      • getPolygonOnElementSet

        public PgPolygonOnElementSet getPolygonOnElementSet()
        The computed geodesic as a polygon that depends on the geometry. Is always a new one for each computation.

      • selectGeometry

        public void selectGeometry(PgGeometryIf geom)
        Currently not supported by display.
        Specified by:
        selectGeometry in interface PvPickListenerIf
        Parameters:
        geom - Now selected geometry of display.

      • pickDisplay

        public void pickDisplay(PvPickEvent pos)
        Get a location in the display with 2d display and 3d world coordinates. Point may be independent of any geometry.
        Specified by:
        pickDisplay in interface PvPickListenerIf
        Parameters:
        pos - Pick event issued by the display
        See Also:
        PvPickListenerIf

      • dragDisplay

        public void dragDisplay(PvPickEvent pos)
        Drag a location in the display with 2d display and 3d world coordinates. Point may be independent of any geometry.
        Specified by:
        dragDisplay in interface PvPickListenerIf
        Parameters:
        pos - Pick event issued by the display
        See Also:
        PvPickListenerIf

      • pickVertex

        public void pickVertex(PgGeometryIf geom,
                       int index,
                       PdVector vertex)
        Get a picked vertex of a geometry.
        Specified by:
        pickVertex in interface PvPickListenerIf
        Parameters:
        geom - Picked geometry on which vertex lies
        index - Index of vertex in vertex array of geometry
        vertex - 3d coordinates of vertex position
        See Also:
        PvPickListenerIf

      • dragVertex

        public void dragVertex(PgGeometryIf geom,
                       int index,
                       PdVector vertex)
        Drag a picked vertex of a geometry.
        Specified by:
        dragVertex in interface PvPickListenerIf
        Parameters:
        geom - Picked geometry on which vertex lies
        index - Index of vertex in vertex array of geometry
        vertex - 3d coordinates of vertex position

      • markVertices

        public void markVertices(PvPickEvent pos)
        Mark a set of vertices of a geometry within a given bounding box.
        Specified by:
        markVertices in interface PvPickListenerIf
        Parameters:
        pos - Contains mark box that is selected.

      • unmarkVertices

        public void unmarkVertices(PvPickEvent pos)
        Unmark a set of vertices of a geometry within a given bounding box.
        Specified by:
        unmarkVertices in interface PvPickListenerIf
        Parameters:
        pos - Contains mark box that is selected.

      • setPickFirst

        public void setPickFirst()
        User shall pick starting point. Call of update(this) is needed afterwards.

      • setPickLast

        public void setPickLast()
        User shall pick endpoint. Call of update(this) is needed afterwards.

      • setMethod

        public void setMethod(int mode)
        Set whether shortest or straightest geodesics are computed. Use the constants of this workshop. You need to call computeWay() and update(this) for changes to take effect.
        See Also:
        SHORTEST, STRAIGHTEST
        Version:
        16.04.04, 1.10 created (ep) Created from setMethodShortest and setMethodStraightest.

      • getMethod

        public int getMethod()
        Whether shortest or straightest geodesics are computed.
        Returns:
        either SHORTEST or STRAIGHTEST.
        See Also:
        setMethod(int)
        Version:
        19.04.04, 1.10 (ep) Made public.

      • setAngle

        public void setAngle(double angle)

      • getAngle

        public double getAngle()

      • setStartBary

        public void setStartBary(PdBary bary)
        Set the starting point of the geodesic.
        Parameters:
        bary - 3dim barycentric coordinates of starting point in start element
        See Also:
        setStartElement(int)

      • setStartElement

        public void setStartElement(int elemindex)
        Set the element where the geodesic shall start in.
        See Also:
        setStartBary(PdBary)

      • setEndBary

        public void setEndBary(PdBary bary)
        Set the endpoint of the geodesic.
        Parameters:
        bary - 3dim barycentric coordinates of endpoint in endelement
        See Also:
        setEndElement(int)

      • setEndElement

        public void setEndElement(int elemindex)
        Set the element where the geodesic shall end in.
        See Also:
        setEndBary(PdBary)

      • isConnected

        public static boolean isConnected(PiVector[] neighb,
                                  PiVector elementrun)
        Checks whether the given element indices belong to an edge connected element run. Added for debugging purposes.
        Parameters:
        neighb - neighbourhood information of geometry
        elementrun - list of element indices
        Returns:
        true if the given list of elements is connected wrt the neighbourhood information
        See Also:
        PgElementSet.getNeighbours()
        Version:
        25.04.04, 1.00 created (ep)

      • getConnectingStrip

        public static int[] getConnectingStrip(PgElementSet geom,
                                       int startelem,
                                       int endelem)
        Gets a strip from startelem to endelem by marking the elements (beginning with startelem) and their neighbours with the 'distance' to the starting element (measured in 'number of elements') until the endelement is reached. Then the algorithm constructs a way by going backwards from endelement to elements with decreasing distance.
        Version:
        09.03.04, 2.00 revised (ep) Made public., 25.08.00, 2.00 revised (ep) Completely new.

      • getShortestInStrip

        public static PgPolygon[] getShortestInStrip(PgElementSet geom,
                                             PdBary start,
                                             PdBary end,
                                             int[] strip,
                                             PiVector outSide,
                                             PiVector outvertind,
                                             PdBaryDir initialDir)
        Deprecated. since 06.05.04, use getShortestInUnfoldedTriangleRun(...) instead.
        Computes the shortest polygon between two points that lies in elements that is given as parameter. It lays the elements into a plane and uses another method to get the points of the curve.
        Parameters:
        start - barycentric coordinates of starting point in element strip[0]
        end - barycentric coordinates of endpoint in element strip[strip.length-1]
        strip - array that contains the global element indices of the elements that shall be traversed on the way from start to end. Must contain the elements in the order in which they shall be traversed.
        outSide - output: contains numbers {0,1}. outSide.getEntry(i)==0 if i-th vertex (excluding starting and endpoint) of shortest polygon lies on left border. ==1 if i-th vertex (exclusive starting and endpoint) of shortest polygon lies on right border.
        outvertind - output: global vertex index in element set of the geometry vertex that the polygon hits with its vertex
        initialDir - output: initial barycentric direction of shortest polygon in element strip[0]
        Returns:
        list of 2-dim polygons:
        [0]= left border of element strip or null if only one element in strip
        [1]= right border of element strip or null if only one element in strip
        [2]= shortest polygon. if only one element in strip then only the length is correct, the rest arbitrary.
        returns null if an error occurred
        Version:
        03.08.00, 1.00 created (ep)

      • getShortest

        public static PgPolygonOnElementSet getShortest(PgElementSet geom,
                                                PdBary start,
                                                int startelem,
                                                PdBary end,
                                                int endelem)
        Computes a shortest geodesic that connects given points on a triangulation. That doesn't have to be THE shortest connection between the points. It is the locally shortest that is generated by contracting the curve in a given triangle run. The one that connects start and endpoint crossing the least number of triangles is used (shortest face dijkstra connection).

        NOTE: The element indices are always of the following form: first element is the starting element, then given a polygon vertex the next vertex has an element assigned that is a neighbour to the element of the current vertex, except the next vertex lies on a vertex.

        Parameters:
        geom - The element set. Must have valid neighourhood information and must be triangulated.
        start - Barycentric coordinates of starting point in starting element
        startelem - The starting element. Global index in geometry. Note that the first element of the computed geodesic may be different from this parameter if startpoint lies on a vertex.
        end - Barycentric coordinates of endpoint in endelement
        endelem - The endelement. Global index in geometry. Note that the last element of the computed geodesic may be different from this parameter if endpoint lies on a vertex.
        Returns:
        A shortest connection between starting and endpoint as a polygon on element set, or null if an error occured.
        See Also:
        PgPolygonOnElementSet
        Version:
        08.08.00, 1.00 created (ep)

      • getShortest

        public static PgPolygonOnElementSet getShortest(PgElementSet geom,
                                                PdBary start,
                                                int startelem,
                                                PdBary end,
                                                int endelem,
                                                PiVector trianglerun,
                                                PgPolygonOnElementSet outpoly)
        Computes a shortest geodesic that connects given points on a triangulation. That doesn't have to be THE shortest connection between the points. It is the locally shortest that is generated by contracting the curve in a given triangle run. If no triangle run is given, then the one that connects start and endpoint crossing the least number of triangles is used (shortest face Dijkstra connection).

        NOTE: The element indices are always of the following form: first element is the starting element, then given a polygon vertex the next vertex has an element assigned that is a neighbour to the element of the current vertex, except the next vertex lies on a vertex.

        Parameters:
        geom - The element set. Must have valid neighbourhood information and must be triangulated. Must NOT have degenerate edges.
        start - Barycentric coordinates of starting point in starting element
        startelem - The starting element. Global index in geometry. Note that the first element of the computed geodesic may be different from this parameter if startpoint lies on a vertex.
        end - Barycentric coordinates of endpoint in endelement
        endelem - The endelement. Global index in geometry. Note that the last element of the computed geodesic may be different from this parameter if endpoint lies on a vertex.
        trianglerun - A list of connected triangles from startelem to endelem, that will be used as the first guess. May be null. As output: The triangle run which contains the computed geodesic is returned here.
        outpoly - Result is put here if not null. New polygon is allocated if null. Is returned as function value.
        Returns:
        A (locally) shortest connection between starting and endpoint as a polygon on element set, or null if an error occured.
        See Also:
        PgPolygonOnElementSet
        Version:
        09.03.04, 1.00 created from previous method (ep)

      • getShortest

        public static PgPolygonOnElementSet getShortest(PgElementSet geom,
                                                PdBary start,
                                                int startelem,
                                                PdBary end,
                                                int endelem,
                                                PiVector trianglerun,
                                                PgPolygonOnElementSet outpoly,
                                                PgElementSet unfolded,
                                                PiVector vertexlist,
                                                PiVector left,
                                                PiVector right,
                                                PdVector previous,
                                                PdVector next,
                                                PdVector t2d,
                                                PdBary tempbary)
        Computes a shortest geodesic that connects given points on a triangulation. That doesn't have to be THE shortest connection between the points. It is the locally shortest that is generated by contracting the curve in a given triangle run. If no triangle run is given, then the one that connects start and endpoint crossing the least number of triangles is used (shortest face Dijkstra connection).

        NOTE: The element indices are always of the following form: first element is the starting element, then given a polygon vertex the next vertex has an element assigned that is a neighbour to the element of the current vertex, except the next vertex lies on a vertex.

        Parameters:
        geom - The element set. Must have valid neighbourhood information and must be triangulated. Must NOT have degenerate edges.
        start - Barycentric coordinates of starting point in starting element
        startelem - The starting element. Global index in geometry. Note that the first element of the computed geodesic may be different from this parameter if startpoint lies on a vertex.
        end - Barycentric coordinates of endpoint in endelement
        endelem - The endelement. Global index in geometry. Note that the last element of the computed geodesic may be different from this parameter if endpoint lies on a vertex.
        trianglerun - A list of connected triangles from startelem to endelem, that will be used as the first guess. May be null. As output: The triangle run which contains the computed geodesic is returned here.
        outpoly - Result is put here if not null. New polygon is allocated if null. Is returned as function value.
        unfolded - temporary 2d geometry for unfolded triangle runs; may be null.
        vertexlist - variable size temporary container, references to left and right boundary in unfolded geometry; may be null.
        left - variable size temporary container for left unfolded boundary; may be null.
        right - variable size temporary container for right unfolded boundary; may be null.
        previous - temporary 2d vector; may be null.
        next - temporary 2d vector; may be null.
        t2d - temporary 2d vector; may be null.
        tempbary - temporary barycentric coordinates in a triangle; may be null.
        Returns:
        A (locally) shortest connection between starting and endpoint as a polygon on element set, or null if an error occured.
        See Also:
        PgPolygonOnElementSet
        Version:
        06.05.04, 2.00 rewrite (ep) Complete rewrite for new 2d-getShortest method.
        09.03.04, 1.00 created from previous method (ep)

      • unfoldTriangleRun

        public static PiVector unfoldTriangleRun(PgElementSet geom,
                                         PiVector run,
                                         PgElementSet unfolded,
                                         PiVector left,
                                         PiVector right)
        Triangle number i in given run is triangle i in unfolded geometry. The same local indices are used for the vertices of the triangle. (geom.getElement(run.getEntry(i)).getEntry(k) is unfolded to unfolded.getElement(i).getEntry(k).)

        The generated geometry has no neighbourhood information or normals.

        Parameters:
        geom - a triangulation with dimOfVertices >= 3; may not contain degenerate edges
        run - must have length >= 1 and must be a connected list of triangles in geom
        unfolded - output is a 2d geometry
        left - left and right contain vertex indices in unfolded geometry where left[i],right[i] is the i-th diagonal. I.e. both can contain intervals i,i+k with identical indices that represent the same point on the bounds of unfolded. They include both initial and endvertex.
        right - see left
        Returns:
        the modified triangle run or null if error occurred
        Version:
        06.05.04, 1.00 created (ep)

      • getShortestInUnfoldedTriangleRun

        public static PiVector getShortestInUnfoldedTriangleRun(PgElementSet unfolded,
                                                        PiVector left,
                                                        PiVector right,
                                                        PiVector output)
        Takes a triangle run (unfolded to 2d) and computes the shortest connection in this closed polygon between the start and end vertex. Returned is a sequence of indices to the lists of the left and right boundary. Use unfoldTriangleRun(...) to get the data needed by this method from a higher dimensional surface.
        Run must contain at least 2 triangles.
        Algorithm is the one from Lee, Preparata; Euclidean Shortest Paths in the Presence of Rectilinear Barriers; Networks vol 14 (1984).
        Parameters:
        unfolded - 2d triangle run
        left - Sequence of vertex indices in 'unfolded' that describe the left hand boundary of the run. It implicitely contains information about the behaviour of the diagonals (inner edges): A boundary vertex with N diagonals emanating from it is repeated N times in sequence. The sequence contains the first and last vertex of the triangle run exactly once.
        right - same as 'left' for the right hand boundary
        output - contains indices for left/right arrays of the vertices that are hit. negative index refers to right array, positive to left array
        Returns:
        same instance as parameter 'output' or a new instance if 'output' is null.
        Version:
        06.05.04, 1.00 created (ep)

      • getDijkstraDistance

        public static PiVector getDijkstraDistance(PgElementSet geom,
                                           PiVector front)
        Computes the combinatorial edge distance of all vertices to a given center vertex respectively on a given set of vertices using Dijkstra's algorithm.
        Parameters:
        geom - The element set. Neighourhood information is not needed.
        front - Indices of vertices on the initial front.
        Returns:
        Distance of each vertex to the given center vertex.
        Version:
        15.02.02, 1.01 revised (ur) Slight bug removed in creating adjacent vertices list.
        19.01.02, 1.00 created (kp)

      • removeLoops

        public static int removeLoops(int[] source,
                              int len,
                              int[] temp)
        Removes subintervals with same starting and ending value (processing from left to right), for instance 10,9,5,7,2,10,2 becomes 10,2
        Parameters:
        source - inout (source with loops removed is put here)
        len - number of entries in source to be considered
        temp - should be of length >= max_i(source[i]) (no check performed)
        Returns:
        length of relevant output entries in parameter 'source'
        Version:
        21.04.04, 1.00 created (ep)

      • getEuclideanDijkstraDistance

        public static PgVectorField getEuclideanDijkstraDistance(PgElementSet geom,
                                                         PiVector front,
                                                         PgVectorField distance)
        Computes the edge distance of all vertices to a given center vertex respectively on a given set of vertices using Dijkstra's algorithm. The edge weight is the Euclidean length of the edge.
        Returns:
        PdVector dist of each vertex to the initial vertices.
        Version:
        16.02.04, 1.00 created (kh)
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