Comparing geometry

To say that two surfaces or two curves are equal is ambiguous, since there is more than one interpretation of the concept. For example, with two planes:

• They could be coplanar, but the normals could be opposed.
• They could be coplanar, with normals having the same sense, but their frames and hence their parameterization might be different.
• They might be identical in every way.

You should not use the == operator with surface and curve types, since that will only test for reference equality.

Geometry.IsCoincident and ITrimmedCurve.lsCoincident are provided to make comparisons. They only test for coincidence, which means any of the above cases would pass.