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Keep Mini map static after rotating / zooming with camera

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Hi I am making a 2D game, where the Camera is able to rotate / zoom in or out on the camera focus (the player usually).

However my game also contains a mini-map, and so far whenever I have to rotate / zoom my camera the mini-map rotates and zooms accordingly. This behaviour was expected, but now I am a little stuck on "un-doing" the changes the view transformation has on my mini-map. What I want to happen is to essentially keep my mini-map statically in the same position throughout the game no matter how the camera rotates or zooms.

I am extremely rusty with my linear algebra / 3D transformations but I have tried the following...

My first thought was, I thought all I had to do was to transform the mini-map origin point with the view matrix, then undo the scaling of the zoom against the mini-map width / height. The zooming was fixed, but the mini-map still rotated so this did not work.

My second try, I remembered to undo the change of a matrix, I would have to multiply the transform by its inverse. So I tried to calculate the inverse matrix, however the determinant of the view matrix was 0, so I could not find an inverse.

Ok... well I guess I'll just see if I can get the rotation down, since I got the zoom to work... So I transformed my mini-map origin by the inverse rotation matrix applied by the view matrix... The mini-map is rotating now, but is not staying in the fixed position I was hoping for.

I was wondering, if anyone here can give me a push in the right direction, or a hint towards a more elegant solution overall. If people would like more information I can upload images, show code... But what I wrote above is exactly how my code would look.

Thanks for any help!

Edited by Believe82

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Hi. Why not just have a transfom for minmap and one you use for the camera so that's 2 transformation.

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