Normal Mapping
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Normal Mapping in Unity
If you have read the Lighting in Unity 1 and Lighting in Unity2, you have seen how important normal vectors are for calculating brightness or reflection of a surface in Lighting models.
Normal Mapping is an implementation of Bump Mapping created by (James Blinn).
Normal Mapping can be described simply as creating a set of normal vectors for every pixel to manipulate the view of an object in the lighting model.
It's important to remember that those effects using normal maps are only rendering effects and have no effect on the Geometry of the model.
Normal maps can be added to a standard shader using Unity Editor.
Normal maps are popular with their blueish color, here is why they have this look.
For every Normal map pixel, it’s represented using the RGB model then transformed to x, y, z values.
Red: (0 to 255) transformed to x (-1 to 1)
Green: (0 to 255) transformed to y (-1 to 1)
Blue: (128 to 255) transformed to z (0 to -1)
X, Y values represent the width and the height of the screen, where z represents the depth into the screen.
For any negative Z values, it represents if the pixel is coming out of the screen.
The bluer point is a brighter point for the user whereas other points appear duller and give the illusion of being away or being shaded.
Normal maps allow us to show details of Game objects using textures where no details exist geometrically.
You can transform textures yourself using transform equations, usually, I use this amazing Github project by Christian Petry which is a free tool to create normal maps from textures.
