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Solution structure

The following projects form part of the solution.

• RobustGeometry - main library containing:

  • Predicates - C# port of Shewchuk's exact arithmetic and geometric predicates.
  • HalfedgeMesh - data structure for polygon mesh representation (TODO)
  • Triangulation - Delaunay triangulation routines (TODO)

• RobustGeometry.Test - unit test library, with various helpers. Also contains:

  • FpuControl helper for accessing x86 FPU control state, and various tests to explore floating-point arithmetic.
  • Printing and parsing of binary floating-point representations.

• RobustGeometry.Wpf - Integration with WPF and WPF 3D for visualization (TODO)

Exact arithmetic and floating-point in .NET

To understand whether the exact arithmetic and hence the geometric predicates could be implemented correctly in .NET, I explored floating-point arithmetic in .NET. My conclusion is that under default settings using 'Float64' doubles, the .NET runtime behaves as expected. The actual ECMA/ISO CLI specification allows a more flexible implementation which could be problematic, but is not used in practice. For additional safety it would be possible to check or control the relevant FPU control state.