Add clockwise and counterclockwise methods to Direction

[alice-i-cecile]

This enables easy rotation code for both cameras and object positioning.

[alice-i-cecile]

Initial external draft and tests. These should take self, rather than a Direction argument, but otherwise this should be trivial to port over.

/// Rotates a hex [`Direction`] one step clockwise.
#[must_use]
pub fn clockwise(direction: Direction) -> Direction {
    use Direction::*;
    match direction {
        BottomRight => Bottom,
        TopRight => BottomRight,
        Top => TopRight,
        TopLeft => Top,
        BottomLeft => TopLeft,
        Bottom => BottomLeft,
    }
}

/// Rotates a hex [`Direction`] one step counterclockwise.
#[must_use]
pub fn counterclockwise(direction: Direction) -> Direction {
    use Direction::*;
    match direction {
        BottomRight => TopRight,
        TopRight => Top,
        Top => TopLeft,
        TopLeft => BottomLeft,
        BottomLeft => Bottom,
        Bottom => BottomRight,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn rotations_reverse_each_other() {
        for direction in Direction::ALL_DIRECTIONS {
            assert_eq!(direction, counterclockwise(clockwise(direction)));
            assert_eq!(direction, clockwise(counterclockwise(direction)));
        }
    }

    #[test]
    fn six_rotations_comes_home() {
        for direction in Direction::ALL_DIRECTIONS {
            let mut cw_direction = direction;
            let mut ccw_direction = direction;

            for _ in 0..6 {
                cw_direction = clockwise(cw_direction);
                ccw_direction = counterclockwise(ccw_direction);
            }

            assert_eq!(direction, cw_direction);
            assert_eq!(direction, ccw_direction);
        }
    }
}

[ManevilleF]

Great suggestion !

Since Hex has :

• rotate_left for counter clockwise
• rotate_right for clockwise

I think Direction and Hex rotation methods should follow similar patterns, I prefer right/left but clockwise/counter_clockwise are more explicit

Feel free to open a MR !

[alice-i-cecile]

Yep, I'm fine with making these match :)