Why is different a point3d of element and a point in range3d of element?

Hi Hirotaka,

at first, please read and follow this forum best practices, especially:

• Use standardized subject format, e.g. [MStn CE U13 VBA] Why...
• Specify exactly what product and version do you use (solved usually by correct subject format).
• Do not describe what you do, but share the code.

Unfortunately without sharing your code it's not quite clear what your issue is. Even a basic information like what is your element are not shared (e.g. element point of circle can be its center).

Be aware there is not such definition that "element point" is equal to the element range:

• Element points (let's say lines string vertices) are X,Y,Z structures of type double.
• Element range is the smallest rectangle or box around the element, expressed in integer coordinates (in UORs).

It means typically the range is slightly bigger (even when the difference is very small, because calculated in UORs, not master units) than the element itself.

With regards,

  Jan

Hi Hirotaka,

at first, please read and follow this forum best practices, especially:

• Use standardized subject format, e.g. [MStn CE U13 VBA] Why...
• Specify exactly what product and version do you use (solved usually by correct subject format).
• Do not describe what you do, but share the code.

Unfortunately without sharing your code it's not quite clear what your issue is. Even a basic information like what is your element are not shared (e.g. element point of circle can be its center).

Be aware there is not such definition that "element point" is equal to the element range:

• Element points (let's say lines string vertices) are X,Y,Z structures of type double.
• Element range is the smallest rectangle or box around the element, expressed in integer coordinates (in UORs).

It means typically the range is slightly bigger (even when the difference is very small, because calculated in UORs, not master units) than the element itself.

With regards,

  Jan

Thank you Jan. I understood very much about the way to write when I post.

[V8i SS4 VBA] Why...

I am writing...

    Dim ee As ElementEnumerator
    Set ee = ActiveModelReference.GetSelectedElements
    Dim elel As LineElement
    Do While ee.MoveNext
        Set elel = ee.Current
    Loop
    
    Dim sizeX As Double
    sizeX = elel.EndPoint.X - elel.StartPoint.X
    
    If (elel.Range.High.X - elel.Range.Low.X) = sizeX Then
        Debug.Print "yes"
    Else
        Debug.Print "no"
    End If

hirotaka nisimura said:

I am writing...

Your code has two crucial flaws!

Do While ee.MoveNext
    Set elel = ee.Current
Loop

What is expected this code will do? You iterate all elements in selection set, but that's all. The test is done for the last element only, outside the loop.

If (elel.Range.High.X - elel.Range.Low.X) = sizeX Then

It's not quite clear what do you want to achieve, because the range is not the size. The size of element is something not exactly defined and can have different characteristics (line vs ellipse vs B-spline curve). But if the element range is enough (but as explained by my and illustrated on Jon's picture, it's not exact size), it can be used.

But not in this way!

You never (never never never) can test equality of two numbers represented internally using floating point. It's not possible to test equality of any decimal variable (some exceptions exist in some languages and decimal types).

To understand why requires some math knowledge and long textual description (many of such explanations can be easily found on Internet, often linked article is e.g. this one), but in this case it would be enough to think how you want to check equality of length e.g. 23.29329830483983 (plus the fact that numbers in floating point arithmetic are typically approximated only)?

MicroStation VBA offers methods to compare Poin2d and Point3d for equality using defined tolerance, but I think there is no such method available for a plain double. Often used approach is to "epsilon test", mentioned also in article I linked. It can be expressed like:

ABS(numA - numB) < tolerance

which allows to compare not numbers for equality (because it technically wrong), but to compare inequality (which is fine) between tolerance and the numbers difference.

A solution can also be to transform double into Point2d and to use Point2dEqualTolerance VBA method or to do not test equality but compare size in terms smaller / bigger.

With regards,

  Jan