Function gather_voxel_first_f32_gpu_buffers 

pub fn gather_voxel_first_f32_gpu_buffers(
    runtime: &WgpuRuntime,
    values: &Buffer,
    segments: &GpuVoxelSegments,
) -> SpatialResult<Vec<f32>>

Gathers the first point’s f32 value using GPU-resident segment buffers.