feat: Composable vertex position generators with event number#5308
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paulgessinger wants to merge 8 commits intoacts-project:mainfrom
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feat: Composable vertex position generators with event number#5308paulgessinger wants to merge 8 commits intoacts-project:mainfrom
paulgessinger wants to merge 8 commits intoacts-project:mainfrom
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…port Extend PrimaryVertexPositionGenerator interface to receive the event number, enabling generators that vary their output over time. Add two new generators: - AdditiveVertexPositionGenerator: composes multiple generators by summing their outputs, allowing layered vertex smearing strategies. - LumiBlockVertexPositionGenerator: produces a beamspot offset that is constant within a configurable luminosity block and changes between blocks using a deterministic PRNG seeded by block number. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
…xGenerator Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Bind PrimaryVertexPositionGenerator.__call__ to Python so generators can be invoked directly in tests. Add tests that verify: - FixedVertexGenerator returns the configured position - GaussianVertexGenerator produces varying positions - AdditiveVertexGenerator sums constituent outputs correctly - LumiBlockVertexGenerator is consistent within a block and varies across blocks - Composed Gaussian + LumiBlock generator behaves correctly Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
andiwand
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Apr 1, 2026
| std::size_t eventNumber) const override { | ||
| std::size_t block = eventNumber / blockSize; | ||
| // Deterministic per block: same block always gives the same offset. | ||
| std::mt19937 blockRng(block); |
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even simpler than I imagined it first. should we allow to inject a seed here / actually inject the user provided seed somehow?
or get a random number from the central RNG+seed and use it as a seed here overall
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Yeah that's probably a good call. We just need to make sure it generates the exact same offset inside the block. Ideally the global seed that is passed in via the RNG instance should be respected.
Wraps another vertex generator and applies a deterministic per-lumi-block rotation (beam tilt) to its spatial output. The tilt angles around x and y are drawn from Gaussians seeded by a salted block number, so they are uncorrelated with LumiBlockVertexPositionGenerator when using the same block size. Includes Python bindings and tests verifying per-block consistency, length preservation, seed decorrelation, and full composition with Gaussian + tilt + positional shift. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Missed call site that also invokes the vertex generator. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Replace the RandomEngine typedef (std::mt19937) with a thin wrapper class that stores the seed it was constructed with. This lets lumi-block vertex generators derive deterministic, user-seed-dependent per-block RNG seeds via boost::hash_combine(rng.seed(), blockNumber). The wrapper satisfies UniformRandomBitGenerator so all existing code (distributions, templates, function signatures) works unchanged. Update LumiBlockVertexPositionGenerator and LumiBlockRotationVertexPositionGenerator to incorporate rng.seed() into their per-block seeds, ensuring different user seeds produce different beamspot trajectories. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add combinedWith(extra) method to RandomEngine that returns a new engine whose seed is hash_combine(this->seed(), extra). This encapsulates the seed derivation pattern in one place. Simplify lumi-block generators to use rng.combinedWith(block) instead of manual boost::hash_combine calls. The rotation generator chains rng.combinedWith(block).combinedWith(salt) for decorrelation. Move boost/functional/hash.hpp include from VertexGenerators.hpp into RandomNumbers.hpp where the hash logic now lives. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Remove redundant m_engine() from RandomEngine default constructor initializer list - Use CTAD for std::normal_distribution in LumiBlockVertexPositionGenerator and LumiBlockRotationVertexPositionGenerator Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
PrimaryVertexPositionGeneratorinterface to receive the event number, enabling vertex generators that vary their output over timeAdditiveVertexPositionGeneratorthat composes multiple generators by summing their outputsLumiBlockVertexPositionGeneratorthat produces a beamspot offset constant within a configurable luminosity block, changing between blocks via a deterministic PRNG seeded by block numberExample usage (Python)
Test plan
AdditiveVertexGeneratorcomposition in PythonLumiBlockVertexGeneratorproduces consistent offsets within a block and different offsets across blocks🤖 Generated with Claude Code