Version: 2022.3

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# 法线贴图（凹凸贴图）

Unity uses Y+ normal maps, sometimes known as OpenGL format.

# 如何创建和使用凹凸贴图

Bump mapping is a relatively old graphics technique, but is still one of the core methods required to create detailed realistic real-time graphics. Bump Maps are also commonly referred to as Normal Maps or Height Maps, however these terms have slightly different meanings which will be explained below.

## 什么是表面法线？

To really explain how normal mapping works, we will first describe what a “normal” is, and how it is used in real-time lighting. Perhaps the most basic example would be a model where each surface polygon is lit simply according to the surface angles relative to the light. The surface angle can be represented as a line protruding in a perpendicular direction from the surface, and this direction (which is a vector) relative to the surface is called a “surface normal”, or simply, a normal.

## 什么是法线贴图？

This is a simple normal map, containing the bump information for some raised rectangles and text. This normal map can be imported into Unity and placed into Normal Map slot of the Standard Shader. When combined in a material with a colour map (the Albedo map) and applied to the surface of the cylinder mesh above, the result looks like this:

## 凹凸贴图、法线贴图和高度贴图有什么区别？

Modern real-time 3D graphics hardware rely on Normal Maps, because they contain the vectors required to modify how light should appear to bounce of the surface. Unity can also accept Height Maps for bump mapping, but they must be converted to Normal Maps on import in order to use them.

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