feat: Add displaced vertex generator

Examples/Algorithms/Generators/ActsExamples/Generators/VertexGenerators.hpp

@@ -46,4 +46,37 @@ struct GaussianPrimaryVertexPositionGenerator
   }
 };
 
+//
+struct GaussianDisplacedVertexPositionGenerator
+    : public EventGenerator::PrimaryVertexPositionGenerator {
+  double rMean = 0;
+  double rStdDev = 1;
+  double zMean = 0;
+  double zStdDev = 1;
+  double tMean = 0;
+  double tStdDev = 1;
+
+  Acts::Vector4 operator()(RandomEngine& rng) const override {
+    double min_value = -M_PI;  // -π
+    double max_value = M_PI;   // π
+
+    std::uniform_real_distribution<> uniform(min_value, max_value);
+
+    std::normal_distribution<double> rDist(rMean, rStdDev);
+    std::normal_distribution<double> zDist(zMean, zStdDev);
+    std::normal_distribution<double> tDist(tMean, tStdDev);
+
+    // Generate random values from normal distributions
+    double r = rDist(rng);
+    double phi = uniform(rng);  // Random angle in radians
+    double z = zDist(rng);
+    double t = tDist(rng);
+
+    // Convert cylindrical coordinates to Cartesian coordinates
+    double x = r * std::cos(phi);
+    double y = r * std::sin(phi);
+
+    return Acts::Vector4(x, y, z, t);
+  }
+};
 }  // namespace ActsExamples

Examples/Python/src/Generators.cpp

@@ -115,6 +115,43 @@ void addGenerators(Context& ctx) {
           &ActsExamples::GaussianPrimaryVertexPositionGenerator::stddev)
       .def_readwrite(
           "mean", &ActsExamples::GaussianPrimaryVertexPositionGenerator::mean);
+  py::class_<
+      ActsExamples::GaussianDisplacedVertexPositionGenerator,
+      ActsExamples::EventGenerator::PrimaryVertexPositionGenerator,
+      std::shared_ptr<ActsExamples::GaussianDisplacedVertexPositionGenerator>>(
+      mex, "GaussianDisplacedVertexPositionGenerator")
+      .def(py::init<>())
+      .def(py::init([](double rMean, double rStdDev, double zMean,
+                       double zStdDev, double tMean, double tStdDev) {
+             ActsExamples::GaussianDisplacedVertexPositionGenerator g;
+             g.rMean = rMean;
+             g.rStdDev = rStdDev;
+             g.zMean = zMean;
+             g.zStdDev = zStdDev;
+             g.tMean = tMean;
+             g.tStdDev = tStdDev;
+             return g;
+           }),
+           py::arg("rMean"), py::arg("rStdDev"), py::arg("zMean"),
+           py::arg("zStdDev"), py::arg("tMean"), py::arg("tStdDev"))
+      .def_readwrite(
+          "rMean",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::rMean)
+      .def_readwrite(
+          "rStdDev",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::rStdDev)
+      .def_readwrite(
+          "zMean",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::zMean)
+      .def_readwrite(
+          "zStdDev",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::zStdDev)
+      .def_readwrite(
+          "tMean",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::tMean)
+      .def_readwrite(
+          "tStdDev",
+          &ActsExamples::GaussianDisplacedVertexPositionGenerator::tStdDev);
 
   py::class_<
       ActsExamples::FixedPrimaryVertexPositionGenerator,