Reimplementing GET_OFFSET_FROM_ENTITY_GIVEN_WORLD_COORDS manually?

I have this class where I don't want to use natives, so I'm trying to reimplement this. Brain says no though.
I thought it should be possible with a few Vector3's:
 base position in world coords
 base rotation
 offset position in world coords
I can't figure it out though. Can anybody help?
Edit  Never mind. I took ScriptHookVDotNet's Camera::GetOffsetInWorldCoords and adapted it for my own, and it seems to work:
Vector3 GetOffsetInWorldCoords(Vector3 baseP, Vector3 rotation, Vector3 direction, Vector3 offset) { Vector3 forward = direction; const double d2R = 0.01745329251994329576923690768489; double num1 = System.Math.Cos(rotation.Y * d2R); double x = num1 * System.Math.Cos(rotation.Z * d2R); double y = num1 * System.Math.Sin(rotation.Z * d2R); double z = System.Math.Sin(rotation.Y * d2R); Vector3 right = new Vector3((float)x, (float)y, (float)z); Vector3 up = Vector3.Cross(right, forward); return baseP + (right * offset.X) + (forward * offset.Y) + (up * offset.Z); }
Blah, cross products. I never quite understood algebra with vectors.

@ikt great job. I made my own implementation using dot product instead. I wish I had searched on google with parameter site: gta5mods.com instead of just gtaforums.com . I thought there was no information about it, it took me some time to make own reimplementation. I was going to post my findings here as well, but yours is more efficient.

@nm710
Post it anyway, more choice is always better

@ikt Yeah you're right about that, more choice is better.
public Vector3 GetOffsetGivenWorldCoords(Vector3 Origin, Vector3 Rotation, Vector3 Position) { Vector3 RightVector = RelativeRightVector(Rotation); Vector3 ForwardVector = RotationToDirection(Rotation); return new Vector3(1 * Vector3.Dot(RightVector, (Origin  Position)), 1 * Vector3.Dot(ForwardVector, (Origin  Position)), Position.Z  Origin.Z); } public Vector3 RelativeRightVector(Vector3 Rotation)//source is from scripthookdotnet { double num = Math.Cos(Rotation.Y * (Math.PI / 180.0)); return new Vector3((float)(Math.Cos(Rotation.Z * (Math.PI / 180.0)) * num), (float)(Math.Sin(Rotation.Z * (Math.PI / 180.0)) * num), (float)Math.Sin(Rotation.Y * (Math.PI / 180.0))); } public Vector3 RotationToDirection(Vector3 Rotation)//I forgot where I got this from, I had it for a long time { float z = Rotation.Z; float num = z * 0.0174532924f; float x = Rotation.X; float num2 = x * 0.0174532924f; float num3 = Math.Abs((float)Math.Cos((double)num2)); return new Vector3 { X = ((float)Math.Sin(num)) * num3, Y = (float)Math.Cos(num) * num3, Z = (float)Math.Sin(num2) }; }

@ikt I didn't realize your function said "GetOffsetInWorldCoords". My function does the other one and gets the offset.