Rotate 3D Model from a custom position

Question

I have a 3D Model like above in which i want to rotate it from a given location(pointed in red) but I can only rotate it from the middle. How can I rotate it from a custom point.

Edit:

I successfully able to rotate the model from the below position by getting the radius of the model and applying it to the world matrix

        Vector3 point = new Vector3(-radius, 0, 0);
        world = Matrix.CreateTranslation(-radius, 0, 0);

But now I cannot change the position of the object and it always centered in middle of the screen. I think that's because i applied the above code. How can I place it anywhere I want?

Answer 1

Finally i was able to do that,

    Matrix rotation = Matrix.Identity; 

Inside the constructor get the radius and make it minus. because originally it was set to Matrix.Identity

    rotation = Matrix.CreateTranslation(-radius, 0, 0);

Answer 2

You have to bring the point you want to rotate to the (0,0,0) position and then apply the rotation.

Answer 3

You have to translate your custom point to the (0,0,0) and then rotate it from there. If your box is 2 x 5 x 2 and you wanted to rotate it over de the X axis, if were using OpenGL you could do something like this

glTranslatef(-1.0f,-2.5f,-1.0f);
glRotatef(rot, 1.0, 0.0, 0.0);