PointAndDerivatives Method [Visio 2003 SDK Documentation]

Returns a point and its derivatives at a position along a curve's path.

object**.PointAndDerivatives**(t, n, x, y, dx, dy, ddx, ddy)

object     Required. An expression that returns a Curve object.

t     Required Double. The value in the curve's parameter domain to evaluate.

n     Required Integer. 0: get point; 1: point and 1st derivative; 2: point plus first and second derivative.

x     Required Double. Returns x value of curve at t.

y     Required Double. Returns y value of curve at t.

dx     Required Double. Returns first derivative (dx/dt) at t if n > 0.

dy Required Double. Returns first derivative (dy/dt) at t if n> 0.

ddx Required Double. Returns second derivative (ddx/dt) at t if n> 1.

ddy Required Double. Returns second derivative (ddy/dt) at t if n> 1.

Version added

5.0

Remarks

Use the PointAndDerivatives method of the Curve object to obtain the coordinates of a point within the curve's parameter domain and its first and second derivatives.

A Curve object is described in terms of its parameter domain, which is the range [Start(),End()]. The PointAndDerivatives method can be used to extrapolate the curve's path outside [Start(),End()].

Example

This Microsoft Visual Basic for Applications (VBA) macro draws an oval on the document's active page and then retrieves it and iterates through its Paths collection and each Path object to display the coordinates of various points along the curve. Because the shape drawn is an oval, it contains only one path and only one Curve object.

Sub PointAndDerivatives_Example() 
 
    Dim vsoShape As Visio.Shape 
    Dim vsoPaths As Visio.Paths 
    Dim vsoPath As Visio.Path 
    Dim vsoCurve As Visio.Curve 
    Dim dblStartpoint As Double
    Dim dblXCoordinate As Double
    Dim dblYCoordinate As Double
    Dim dblFirstDerivativeX As Double
    Dim dblFirstDerivativeY As Double 
    Dim dblSecondDerivativeX As Double
    Dim dblSecondDerivativeY As Double
    Dim intOuterLoopCounter As Integer
    Dim intInnerLoopCounter As Integer

    'Get the Paths collection for this shape.
    Set vsoPaths = ActivePage.DrawOval(1, 1, 4, 4).Paths 

    'Iterate through the Path objects in the Paths collection.
    For intOuterLoopCounter = 1 To vsoPaths.Count 
        Set vsoPath = vsoPaths.Item(intOuterLoopCounter) 
        Debug.Print "Path object " & intOuterLoopCounter
 
        'Iterate through the curves in a Path object.
        For intInnerLoopCounter = 1 To vsoPath.Count 

            Set vsoCurve = vsoPath(intInnerLoopCounter) 
            Debug.Print "Curve number " & intInnerLoopCounter 

            'Display the start point of the curve. 
            dblStartpoint = vsoCurve.Start 
            Debug.Print "Startpoint= " & dblStartpoint 

            'Use the PointAndDerivatives method to obtain 
            'a point and the first derivative at that point. 
            vsoCurve.PointAndDerivatives (dblStartpoint - 1), 1, _ 
                dblXCoordinate, dblYCoordinate, dblFirstDerivativeX, dblFirstDerivativeY, dblSecondDerivativeX, dblSecondDerivativeY 
            Debug.Print "PointAndDerivative= " & dblXCoordinate, dblYCoordinate, dblFirstDerivativeX, dblFirstDerivativeY

        Next intInnerLoopCounter 
        Debug.Print "This path has " & intInnerLoopCounter - 1 & " curve object(s)." 

    Next intOuterLoopCounter 
    Debug.Print "This shape has " & intOuterLoopCounter - 1 & " path object(s)." 

End Sub  

Applies to | Curve object

See Also | End property | Point method | Points method | Start property