Question

Can anyone help me with this please

I want to be able to rotate a 3D object around a stationary 3D object. Well there will be no movement involved as I just want to draw the objects at their locations once the game starts and then they will remain there for the remainder of the game.

Say for instance I have a object X that is stationary in 3D space. I then have 2 other objects, Y1 and Y2. Both of these objects are stationary as well and cant be moved. All 3 objects are on the same x and y axis. Lets say X is at (0,0,0) and Y1 is at (0,0,-50). I want to draw Y2 at a 45 degree angle from Y1 around the Y-axis but keep it the same distance from X.

Can anyone please suggest the best way of doing this please?
I have tried the following but that just rotates the object around its origin. So I guess I have to rotate it around the world origin? How is this done?

Matrix.CreateRotationY(Rotation) 

Answer 1

I’m not sure what you want, but this is one method for rotate one object around another:

  Vector3 Origin;     // Stationary Object

  float Yaw, Pitch;   // Angles 

  float Distance;     

  Vector3 OrbitOffset = Vector3.UnitX * Distance;

  // Other approach that consider the initial pos of the object to rotate
  // Vector3 OrbitOffset = OrbitPos - Origin;       

  Matrix Rotation = Matrix.CreateFromYawPitchRoll(Yaw, Pitch, 0);

  Vector3.Transform(ref OrbitOffset, ref Rotation, out OrbitOffset);

  Vector3 OrbitPos = Origin + OrbitOffset;  // Final position of the rotated object