topic Re: compare XYZ in Revit API Forum

compare XYZ

jeroen.van.halderen — Fri, 11 Jun 2021 06:55:38 GMT

Hi everyone,

To determine if a point is in a boundingbox I have to determine if the X, Y and Z coordinate of that point is greater than the min point of the boundingbox and smaller than the max point of the boundingbox. When searching for this I could only find the XYZ.IsAlmostEqualTo() method but there was no method to determine if an XYZ is greater than or smaller than another XYZ.

Did I miss something or are the methods to compare XYZs with the API just a little limited? If so it would be really nice to have the above mentioned comparison methods were added to the API in a later version of Revit.

Thanks in advance!

Kind regards,

Jeroen van Halderen

Re: compare XYZ

architect.bim — Fri, 11 Jun 2021 09:40:51 GMT

Hi!

I think such functionality is a bit narrow and unlikely will appear in API. But you can implement it on your own by inheriting the base XYZ class and overloading necessary operators. I am not good enough with C# but in Python it looks like this:

class XYZExtended(DB.XYZ): def __gt__(self, other): if any([self.X < other.X, self.Y < other.Y, self.Z < other.Z]): return False return any([self.X > other.X, self.Y > other.Y, self.Z > other.Z]) def __lt__(self, other): if any([self.X > other.X, self.Y > other.Y, self.Z > other.Z]): return False return any([self.X < other.X, self.Y < other.Y, self.Z < other.Z]) xyz_1 = XYZExtended() xyz_2 = XYZExtended(1, 1, 1) xyz_3 = XYZExtended(-3, -5, -2) print xyz_1 > xyz_2 print xyz_1 > xyz_3 print xyz_3 < xyz_2 # results False True True

Re: compare XYZ

architect.bim — Fri, 11 Jun 2021 09:42:56 GMT

P.S. The logic of comaring two XYZ objects may be more complex than in the exapmle above, but the main idea is there: overload method, define rules which allow you to say that one object is greater than the other.

Good luck! 😃

Re: compare XYZ

jeremy_tammik — Fri, 11 Jun 2021 10:15:49 GMT

Thank you for the valid question, and thanks to Maxim for his very helpful answer.

Afaik, the correct best practice in .NET is to implement a comparison operator named Compare or a Comparer class:

https://duckduckgo.com/?q=.net+comparer

Also, since the X, Y and Z coordinates are real values, you need to define a tolerance and add some fuzz to be able to determine equality.

Here is The Building Coder comparer method for XYZ objects:

https://github.com/jeremytammik/the_building_coder_samples/blob/master/BuildingCoder/BuildingCoder/Util.cs#L32-L349

/// <summary> /// Default tolerance used to add fuzz /// for real number equality detection /// </summary> public const double _eps = 1.0e-9; /// <summary> /// Predicate to determine whether the given /// real number should be considered equal to /// zero, adding fuzz according to the specified /// tolerance /// </summary> public static bool IsZero( double a, double tolerance = _eps ) { return tolerance > Math.Abs( a ); } /// <summary> /// Predicate to determine whether the two given /// real numbers should be considered equal, adding /// fuzz according to the specified tolerance /// </summary> public static bool IsEqual( double a, double b, double tolerance = _eps ) { return IsZero( b - a, tolerance ); } /// <summary> /// Comparison method for two real numbers /// returning 0 if they are to be considered equal, /// -1 if the first is smaller and +1 otherwise /// </summary> public static int Compare( double a, double b, double tolerance = _eps ) { return IsEqual( a, b, tolerance ) ? 0 : (a < b ? -1 : 1); } /// <summary> /// Comparison method for two XYZ objects /// returning 0 if they are to be considered equal, /// -1 if the first is smaller and +1 otherwise /// </summary> public static int Compare( XYZ p, XYZ q, double tolerance = _eps ) { int d = Compare( p.X, q.X, tolerance ); if( 0 == d ) { d = Compare( p.Y, q.Y, tolerance ); if( 0 == d ) { d = Compare( p.Z, q.Z, tolerance ); } } return d; }

Re: compare XYZ

jeroen.van.halderen — Fri, 11 Jun 2021 13:24:22 GMT

@jeremy_tammik thank you for your suggestion, I will take a look at it!