In order to help those that are trying to understand the diference between painting and normal map think in paiting like a “makeup” that is trying to fake the light, in a sculpted head for example, as soon as you turn the head the makeup will look awkward because the light comes from one direction, and the “makeup shadow” is pointing in another direction. Normal maps are kind of “magical makeup”, if you turn your head painted with this magical the shadow will look natural and follows what is expected to happen, everything will be calculated by the program using mathematical and algoritmic parameters… that’s the magical
I hope that this helps to undersand
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Normal maps are basically vectors in a 3D world but are described as a color in a bitmap.
The vector is the direction, of the normal of a (part) of a mesh face.
In the 3D we have an ‘X’, ‘Y’, and ‘Z’ ax. This allows us to identify any point in a 3D space. OR a direction (a vector) to that point, using the 0,0,0 as origin point.
We have also 3 colors, red, green, and blue as RGB-color values. Each has a range from 0 to 255. And is the equivalent of an ‘X’, ‘Y’, or ‘Z’-ax coordinate. A coordinate can be negative also! So this color van from 0 to 255, is divided by half. 0 to 127 as a negative ax, 128 and above positive ax.
A normal map is mainly purple because the ‘X’, and ‘Y’ coordinates are 0 (zero), translated into the color red:128, green:128 (meaning 0 vector direction), and the ‘Z’ ax is 255 for BLUE color. With this blue:255 as Z-ax, the calculated normal vector is then perpendicular to the mesh face.
This created the purple bitmap. Colors like red, green, or darker colors are a representation of a different normal direction. Hence, different glossy, roughness, or displacement effects, because of the calculated normals (by RGB values).
Darker colors, mean negative normal (face inside out).
You can draw your own normal map in Photoshop, GIMP, or Krita, using a base RGB color 128,128,255 and adding slight color variations. What I do is sometimes manipulate a normal map in GIMP, to make things softer. Less extreme color, but still in the 128,128,128 range.
Have fun.
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