ShaderLab syntax: Shader
Shader is the root command of a shader file. Each file must define one (and only one) Shader. It specifies how any objects whose material uses this shader are rendered.
Syntax
Shader "name" { [Properties] Subshaders [Fallback] } Defines a shader. It will appear in the material inspector listed under name. Shaders optionally can define a list of properties that show up as material settings. After this comes a list of SubShaders, and optionally a fallback.
Details
Properties
Shaders can have a list of properties. Any properties declared in a shader are shown in the material inspector inside Unity. Typical properties are the object color, textures, or just arbitrary values to be used by the shader.
SubShaders & Fallback
Each shader is comprised of a list of sub-shaders. You must have at least one. When loading a shader, Unity will go through the list of subshaders, and pick the first one that is supported by the end user's machine. If no subshaders are supported, Unity will try to use fallback shader.
Different graphic cards have different capabilities. This raises an eternal issue for game developers; you want your game to look great on the latest hardware, but don't want it to be available only to those 3% of the population. This is where subshaders come in. Create one subshader that has all the fancy graphic effects you can dream of, then add more subshaders for older cards. These subshaders may implement the effect you want in a slower way, or they may choose not to implement some details.
Examples
Here is one of the simplest shaders possible:
// colored vertex lighting
Shader "Simple colored lighting" {
// a single color property
Properties {
_Color ("Main Color", Color) = (1,.5,.5,1)
}
// define one subshader
SubShader {
Pass {
Material {
Diffuse [_Color]
}
Lighting On
}
}
}
This shader defines a color property _Color (that shows up in material inspector as Main Color) with a default value of (1, 0.5, 0.5, 1). Then a single subshader is defined. The subshader consists of one Pass that turns on vertex lighting and sets up basic material for it.