Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
>
> You wrote: "In blender the shortcut for making the normals consistent is
> (in edit mode or it will open a new scene file) Ctrl + n or to make them
> face inward is Ctrl + Shift + n".
>
> What is the meaning of "making normals consistent", and of "make normals
> face inwards"? I need to understand this.

I have never used Blender, but the analogy in POV-Ray would be this:

A mesh object-- like a simple sphere, for example-- should have ALL of the
triangles' normals facing OUTWARD into the surrounding space, for the sphere to
render correctly. Those would be "consistent normals." Any mesh-creation tool
should do that automatically-- if it's working correctly ;-) But if a triangle
happens to be made 'incorrectly' (that is, the three vector-location-points of a
particular triangle are simply written in the 'reverse order' to what they
should be, looking face-on at the triangle), its normal will actually face in
the opposite direction(!), and will not render correctly. (Or rather, it will
show the INSIDE texture, if the object has one.) BTW, this is a typical mistake
when trying to write triangle vectors *manually*; it's hard to keep track of the
necessary and consistent 'orientation' from triangle to triangle.

Making all the normals "face inwards" would be the opposite of the above. I'm
not clear as to why that would be necessary, but I guess it can be done. (I
don't know if POV-Ray's 'inverse' keyword-- when applied to an object to change
its 'outside' to its 'inside') switches the normals as well; I never thought to
test it.)

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