Vector math refresher

[edgy wadi]

Trying to calculate the position of an offset based on a direction, this picture summarizes what Im thinking of bet but its been a while so Ive been stuck on this, in the 3d space I have an idea how to do this but no clue on 2d lol

Assume the bottom black dot is 0, 0, and the direction is 0.7, 0.7 lets say. Assuming some object or player is facing that direction, I want to get the local offset from that direction, lets say (1, 0) (dotted line indicates where it roughly should be)

Been a while since Ive done vector math like this so would appreciate a refresher!

[blazing cypress]

So, using a local direction you want a local offset?

[river remnant]

cross(direction, planeNormal) gives you the orthogonal normal of the direction in the plane. 2D is just 3D with the planeNormal being (0,0,1)

[shell onyx]

Vector2.Perpendicular does this

Or (x ,y) -> (-y, x)

If I even understand the issue correctly

[uneven lichen]

Just add the offset vector to the position of the player. If I understand the question properly... Which I'm not sure I do as the diagram isn't that clear about what you're looking for.

[edgy wadi]

Probably shouldve made it a bit more clear in the diagram, but my question was to add the offset based on the local direction

So in the diagram I made earlier, (-1, 0) from the direction dot would be 1 unit to the left, but because of the directional vector it gets shifted

But I did end up solving this with a different approach, Ill share it here if I get around to it later

[uneven lichen]

Vector3 localOffset = new(-1, 0);
Vector3 worldPoint = transform.TransformPoint(localOffset);```

or if you don't want it affected by the object's scale:

Vector3 localOffset = new(-1, 0);
Vector3 rotatedOffset = transform.rotation * localOffset;
Vector3 finalPoint = transform.position + rotatedOffset;```

[edgy wadi]

Vector2 spawnDirection = projectileSpawnRule.SpawnLocalOffset.normalized;
Vector2 right = new Vector2(lookDirection.y, -lookDirection.x);
Vector3 spawnPos = (Vector2)transform.position + lookDirection * 
spawnDirection.y + right * spawnDirection.x;

Something like this is what worked for me

slight limitation because I didnt have access to transform.TransformPoint since I wanted to get the position for another object