Recalculating normals - why?

Question Modeling

As a beginner at modeling, I find myself recalculating normals quite a bit.  It's something I see in the tutorials and most of the time it just works.  I understand what normals are and why I need to recalculate them - but what I don't understand is what I am doing in my modeling to require recalculation so much.  I assume this is poor modeling on my part and I'd like to correct it.  Can anybody give examples of how normals get flipped the wrong way in the course of normal modeling?  For example, does it happen frequently when extruding, or duplicating faces, or ???

Thanks for any tips on this.

  • Martin Bergwerf replied

    Hi Eric XTremeDaddy ,

    That is not really a matter of poor modeling! Each Vertex gets a number depending on the order in which they are created and the Normal direction depends on the 'direction' of those Indices. In the case of a quad, there are those 4 possibilities (ignoring rotation):


    Obviously, using SHIFT+N is a lot easier than trying to model so, that all Normals are correct in the first place

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  • Omar Domenech replied

    Yeah don't worry, it's not poor modeling, it's just math and stuff. No one models having in mind the number of a vertex and the direction the face is going to turn out. If anyone is to blame is the universe itself, having mathematics at it core like that.

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