This png makes it more obvious how to "Bake" a proper mesh into a normal map.
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Normal mapping looks pretty good, but its obviously not as good as a proper mesh. Still though, normal-mapping is far, far, far cheaper to calculate. In most cases, normal-mapping is "good enough".
The left polygons are "truly" a polygon. The right 4 shapes is this "fake" technique of normal-mapping.
https://en.wikipedia.org/wiki/Normal_mapping
In particular: https://en.wikipedia.org/wiki/Normal_mapping#/media/File:Nor...
This png makes it more obvious how to "Bake" a proper mesh into a normal map.
----------
Normal mapping looks pretty good, but its obviously not as good as a proper mesh. Still though, normal-mapping is far, far, far cheaper to calculate. In most cases, normal-mapping is "good enough".