Function cpu_parallel_dispatch 

pub fn cpu_parallel_dispatch<F>(
    workgroup_size: [u32; 3],
    groups: [u32; 3],
    num_threads: usize,
    f: F,
)
where
    F: Fn(usize, u32, u32, u32) + Send + Sync,

Run a CPU compute kernel across multiple threads. f receives (thread_id, global_x, global_y, global_z).