What should Vector::UNIT be?

Gobbel2000 · July 9, 2024, 8:18pm

iced-rs/iced/blob/e86920be5b9984b4eb511e5e69efdcbf6ef3d8e4/core/src/vector.rs#L23


      
              pub const fn new(x: T, y: T) -> Self {
                  Self { x, y }
              }
          }
          
          impl Vector {
              /// The zero [`Vector`].
              pub const ZERO: Self = Self::new(0.0, 0.0);
          
              /// The unit [`Vector`].
              pub const UNIT: Self = Self::new(0.0, 0.0);
          }
          
          impl<T> std::ops::Add for Vector<T>
          where
              T: std::ops::Add<Output = T>,
          {
              type Output = Self;
          
              fn add(self, b: Self) -> Self {
                  Self::new(self.x + b.x, self.y + b.y)

In the master branch, Vector::UNIT is defined as the zero-vector (0, 0),
which is obviously not correct. But I’m unsure, what value would be correct.

According to this, a unit vector is any vector with length 1, so there would be many valid values. In terms of what constants would be useful I would suggest providing the unit vectors of the standard basis:

pub const UNIT_X: Self = Self::new(1.0, 0.0);
pub const UNIT_Y: Self = Self::new(0.0, 1.0);

This would allow expressions like Vector::UNIT_X * 4.0 for a vector 4 units in the x direction.

Any other suggestions? Maybe Vector doesn’t need any constants outside ZERO?

lufte · July 10, 2024, 3:18pm

What’s your interest in this particular piece? To me it looks like a bad copy-paste for a constant that is not even being used yet. It will probably be fixed when the author starts using it.

Gobbel2000 · July 10, 2024, 6:31pm

I realize that this is not very impactful, but it’s something I stumbled across and thought it shouldn’t go unmentioned.

hecrj · July 13, 2024, 11:41am

Ah, this is a leftover from a redesign I did a long time ago. Let’s just get rid of it.