Quote: Every 2D vector has two such normals: the right hand and left hand normal. As you might expect, the right hand normal points to the right of the vector, and the left hand normal points to the left. Given a vector a, the right hand normal of a is simply: rn.x = -a.y; rn.y = a.x; and the left hand normal is: ln.x = a.y; ln.y = -a.x; Note that ln = -rn.

            Vector2 R = new Vector2();
            R.X = 10;
            R.Y = 0;

            Vector2 normal_RH = new Vector2();
            normal_RH.X = -CCW.Y;
            normal_RH.Y = CCW.X;

Quote:Original post by raigan
"Right hand normal" simply meant the normal that points to the right of the line, nothing to do with hands and thumbs.

Quote:Original post by raigan
The problem here is one of "left-handed" vs "right-handed" coordinate systems: you're assuming that the vector (0,1) points upward (the way it's taught in math class) while the tutorial assumes that it points downward (the way it exists in some graphics APIs). So the vector (0,1) does in fact point to the right of the vector (1,0), *IF* you consider +y to be in the down direction rather than up.

Quote:Original post by raigan
Well, since I'm one of the authors of the tutorial in question, I can say definitively that by "right hand normal" we meant "normal pointing to the right side of the vector".

The OPs problem was the assumption that (0,1) points up, when in our world that vector points down :)

This may be confusing since we don't explicitly *state* this anywhere, but if you consider e.g Figure 12 at the very bottom of the page -- the right-hand (red) normal of (3,-1) is given as (1,3) -- this can be inferred.

We're used to polygon vertices being listed in counter-clockwise order, and the right-hand side of polygon edges being the "outside" of the polygon. Hence the right-hand normal is the normal pointing to the right side of a vector. I guess this is just a convention.