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Re: 3D backface culling 3rd
Posted by: tat Jul,04.2022-10:15 

Hi Roger

You are right in that you could create an inverse rotation matrix by multiplying 3 simple inverse rotations in the reverse order.

However, if you have a 3x3 rotation matrix result, you should be able to create the inverse by transposing that matrix (flipping the matrix entries across the main diagonal).

e.g. if your rotation matrix is [[a,b,c],[d,e,f],[g,h,i]] the transpose/inverse is [[a,d,g],[b,e,h],[c,f,i]].

This transpose trick only really works for rotations, plus a few other exceptions. If you include translation as well as rotation, the inverse becomes a little more difficult.

Hope this helps,

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Topic Posted by  Date 
3D backface culling ROGer Jul,02.2022-18:59
  3D backface culling 2nd ROGer Jul,02.2022-19:15
    3D backface culling 3rd ROGer Jul,02.2022-19:19
      Re: 3D backface culling 3rd tat Jul,04.2022-10:15
        Re: 3D backface culling 3rd ROGer Jul,05.2022-13:58

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