I'm trying to make an entity system where the entity can have multiple components, like arms and legs, or weapon attachments, but I can't figure out how to get all of the components to stay in the right position when the entity is rotated.

With the code I currently have, the rotation works, but I can't place the components where they are supposed to be. When I try to place the component at the mouse position it doesn't go where it is supposed to, and rather seems to stick to a circle path.

Vector2 newPos = new Vector2(Base.X, Base.Y);

newPos.X += (float)(PositionRelativeToBase.X * Math.Cos(Rotation - MathHelper.ToRadians(PositionRelativeToBase.Y)));
newPos.Y += (float)(PositionRelativeToBase.X * Math.Sin(Rotation - MathHelper.ToRadians(PositionRelativeToBase.Y)));

This is code that I found elsewhere, though, so I don't understand it entirely, so I can't really explains my thoughts behind it.

Thanks for the answer :)

I don't have time to code anything at the moment, though, but I think can figure it out from here, so thanks for the help :)

I got it working! Thanks a lot for your help!

I'm going to try to explain what I did, so that others trying to achieve the same might benefit from it

First I create a child object I place it at the mousepos

entity.childObjects.Add = new Rectangle(ms.X, ms.Y, size.X, size.Y);

Then I store the distance between the childObject and the Base of the parent (I use a list for this at the moment, but you should probably create a class for childObject and have all the information you need there)

entity.ConnectionGap.Add(new Vector2(ms.X - entity.Base.X, ms.Y - entity.Base.Y));

In my entity class, this is what I do to get the right position. As I mentioned, it's probably better to create a childObject class, so that you won't need lots of different lists.

for (int i = 0; i < childObjects.Count; i++)
            {
                Vector2 newPos =
GetPositionOfSatellite(new Vector2(Base.X, Base.Y),
new Vector2(ConnectionGap[i].X, ConnectionGap[i].Y).Length(),
Vector2ToRadian(new Vector2(ConnectionGap[i].X, ConnectionGap[i].Y)) + Rotation); //I changed this method a little, because it inverted my coordinates for some reason

                childObjects[i] = new Rectangle((int)newPos.X, (int)newPos.Y, childObjects[i].Width, childObjects[i].Height);
            }

private float Vector2ToRadian(Vector2 direction)
        {
            return (float)Math.Atan2(direction.Y, direction.X);
        }

I hope I explained the well enough, and that someone will benefit from it