lighttroupe/luz

module MethodsForUserObject
    def first_frame?
        $env[:frame_number] == 1
    end

    #
    # env manipulation
    #
    def with_env(var, value)
        old_value = $env[var]
        return yield if (value == old_value)
        $env[var] = value            # TODO: make cumulative += version
        yield
        $env[var] = old_value
    end

    def with_env_hash(hash)
        old_values = Hash.new
        # Save current value, set new one
        hash.each_pair { |key, value| old_values[key] = $env[key] ; $env[key] = value }
        yield
        # Restore old values
        old_values.each_pair { |key, value| $env[key] = value }
    end

    #
    # special enter/exit helpers
    #
    def with_enter_and_exit(enter, exit)
        old_enter, old_exit = $env[:enter], $env[:exit]
        return yield if (enter == old_enter && exit == old_exit)
        $env[:enter], $env[:exit] = enter.clamp(0.0, 1.0), exit.clamp(0.0, 1.0)
        yield
        $env[:enter], $env[:exit] = old_enter, old_exit
    end

    # Easy way to turn a fuzzy (0.0..1.0) to enter/exit values
    def with_enter_exit_progress(value)
        with_env(:enter, (value < 0.5) ? (value / 0.5) : 1.0) {
            with_env(:exit, (value > 0.5) ? ((value - 0.5) / 0.5) : 0.0) {
                yield
            }
        }
    end

    #
    # special time/beat helpers
    #
    def with_time_shift(second_offset, &proc)
        with_env(:time, ($env[:time] + second_offset), &proc)         # TODO: how about a generic with_env_addition(:time, second_offset) { ... }
    end

    def with_beat_shift(beat_offset)
        old_beat, old_beat_number = $env[:beat], $env[:beat_number]
        $env[:beat] += beat_offset
        $env[:beat_number] += beat_offset
        yield
        $env[:beat], $env[:beat_number] = old_beat, old_beat_number
    end
end