A plane that goes through two points and is parallel to player.transform.forward

Question

I've got a player with a sword and the two points on a target are from OnTriggerEnter and OnTriggerExit. Then I want to create a slicing plane that is parallel to player.transform.forward - it can be vertical, horizontal or on an angle (parallel to the player forward - which is always horizontal).

To define the plane I need its normal/up vector and one of the two points and it is infinite. So I'd like code for the plane's normal based on position1, position2, and player.transform.forward.

Answer 1

Based on LoïcLeGrosFrère I did this: (EzySlice also has a Plane class)

UnityEngine.Plane plane = new UnityEngine.Plane(sliceStartPos, sliceEndPos, playerPos);

SlicedHull hull = objectToSlice.Slice(sliceStartPos, plane.normal, crossMat);

An alternative:

public Vector3 GetPlaneNormal(Vector3 a, Vector3 b, Vector3 c)
{
    return Vector3.Normalize(Vector3.Cross(b - a, c - a));
}
Vector3 planeNormal = GetPlaneNormal(sliceStartPos, sliceEndPos, playerPos);

SlicedHull hull = objectToSlice.Slice(sliceStartPos, planeNormal, crossMat);