Function get_spread 

pub fn get_spread(
    world: &Arc<World>,
    pos: BlockPos,
    state: BlockStateId,
    fluid_id: FluidRef,
    drop_off: u8,
    slope_find_distance: u8,
) -> Vec<(Direction, FluidState)>

Gets the spread map for a fluid.

Returns a list of (Direction, FluidState) pairs to spread to, filtered to the directions with the shortest slope distance. For each candidate direction, the target’s existing FluidState.canBeReplacedWith() is checked before adding it to the result.

Vanilla equivalent: FlowingFluid.getSpread().