build_cluster_ids()

std::vector< uint32_t > MayaFlux::Nodes::Network::PhysicsOperator::build_cluster_ids ( ) const

overridevirtual

Per-particle collection index, global index order.

Returns

get_point_count() elements, entry i equal to the index of the CollectionGroup particle i belongs to in get_collections() order. All zero when there is at most one collection.

The single source of truth for "which complete vertex-array pack does this particle belong to", consumed by any GPU-side stage that needs to respect collection boundaries in a neighbour query (the spatial hash's ClaimProcessor/HashDensityColorProcessor, and optionally GpuFieldOperator's own cluster-scoped bindings): each such consumer uploads this once, at wiring time, into whatever state field it declares for the purpose, rather than every consumer reaching into get_collections() and re-deriving the same prefix sum independently.

Overrides GraphicsOperator::build_cluster_ids(), whose default (every entry 0) is exactly what this returns when there is at most one collection; the override only differs once a second one exists.

Reimplemented from MayaFlux::Nodes::Network::GraphicsOperator.

Definition at line 859 of file PhysicsOperator.cpp.

{
    std::vector<uint32_t> ids(get_vertex_count(), 0U);
 
    if (m_collections.size() <= 1) {
        return ids;
    }
 
    size_t offset = 0;
    uint32_t cluster = 0;
    for (const auto& group : m_collections) {
        const size_t count = group.collection->get_vertex_count();
        for (size_t i = 0; i < count && offset + i < ids.size(); ++i) {
            ids[offset + i] = cluster;
        }
        offset += count;
        ++cluster;
    }
 
    return ids;
}

References count, get_vertex_count(), ids, m_collections, and offset.

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