diff --git a/doc/api/next_api_changes/behavior/24062-tb.rst b/doc/api/next_api_changes/behavior/24062-tb.rst new file mode 100644 index 000000000000..7e5beaecba53 --- /dev/null +++ b/doc/api/next_api_changes/behavior/24062-tb.rst @@ -0,0 +1,8 @@ +``TrapezoidMapTriFinder`` uses different random number generator +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The random number generator used to determine the order of insertion of +triangle edges in ``TrapezoidMapTriFinder`` has changed. This can result in a +different triangle index being returned for a point that lies exactly on an +edge between two triangles. This can also affect triangulation interpolation +and refinement algorithms that use ``TrapezoidMapTriFinder``. diff --git a/src/tri/_tri.cpp b/src/tri/_tri.cpp index b7a87783de29..80a14201645b 100644 --- a/src/tri/_tri.cpp +++ b/src/tri/_tri.cpp @@ -12,6 +12,7 @@ #include #include +#include TriEdge::TriEdge() @@ -1465,8 +1466,8 @@ TrapezoidMapTriFinder::initialize() _tree->assert_valid(false); // Randomly shuffle all edges other than first 2. - RandomNumberGenerator rng(1234); - std::random_shuffle(_edges.begin()+2, _edges.end(), rng); + std::mt19937 rng(1234); + std::shuffle(_edges.begin()+2, _edges.end(), rng); // Add edges, one at a time, to tree. size_t nedges = _edges.size(); @@ -2056,16 +2057,3 @@ TrapezoidMapTriFinder::Trapezoid::set_upper_right(Trapezoid* upper_right_) if (upper_right != 0) upper_right->upper_left = this; } - - - -RandomNumberGenerator::RandomNumberGenerator(unsigned long seed) - : _m(21870), _a(1291), _c(4621), _seed(seed % _m) -{} - -unsigned long -RandomNumberGenerator::operator()(unsigned long max_value) -{ - _seed = (_seed*_a + _c) % _m; - return (_seed*max_value) / _m; -} diff --git a/src/tri/_tri.h b/src/tri/_tri.h index 28c8e07933cc..29b4ff81fb17 100644 --- a/src/tri/_tri.h +++ b/src/tri/_tri.h @@ -791,28 +791,4 @@ class TrapezoidMapTriFinder Node* _tree; // Root node of the trapezoid map search tree. Owned. }; - - -/* Linear congruential random number generator. Edges in the triangulation are - * randomly shuffled before being added to the trapezoid map. Want the - * shuffling to be identical across different operating systems and the same - * regardless of previous random number use. Would prefer to use a STL or - * Boost random number generator, but support is not consistent across - * different operating systems so implementing own here. - * - * This is not particularly random, but is perfectly adequate for the use here. - * Coefficients taken from Numerical Recipes in C. */ -class RandomNumberGenerator -{ -public: - RandomNumberGenerator(unsigned long seed); - - // Return random integer in the range 0 to max_value-1. - unsigned long operator()(unsigned long max_value); - -private: - const unsigned long _m, _a, _c; - unsigned long _seed; -}; - #endif pFad - Phonifier reborn

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