All Shader files in Unity are written in a declarative language called ShaderLab. In the file, a nested-braces
syntax declares various things that describe the shader – for example, which shader properties to show in the Material InspectorA Unity window that displays information about the currently selected GameObject, Asset or Project Settings, alowing you to inspect and edit the values. More info
See in Glossary, what kind of hardware fallbacks to perform, and what kind of blending modes to use. Actual shader code is written in
CGPROGRAM snippets inside the same shader file. For more information, see Writing Surface Shaders and Writing vertex and fragment shaders.
This page and the child pages describes the nested-braces “ShaderLab” syntax. The CGPROGRAM snippets are written in regular
HLSL/Cg shading language, see their documentation pages.
ShaderA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
See in Glossary 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.
Shader "name" { [Properties] Subshaders [Fallback] [CustomEditor] }
Defines a shader. It will appear in the material inspector listed under name. Shaders optionally can define a list of properties that show up in material inspector. After this comes a list of SubShadersEach shader in Unity consists of a list of subshaders. When Unity has to display a mesh, it will find the shader to use, and pick the first subshader that runs on the user’s graphics card. More info
See in Glossary, and optionally a fallback and/or a custom editor declaration.
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.
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.
Shader “level of detailThe Level Of Detail (LOD) technique is an optimization that reduces the number of triangles that Unity has to render for a GameObject when its distance from the Camera increases. Each LOD level has either a Mesh with a Mesh Renderer component (Mesh LOD level) or a Billboard Asset with a Billboard Renderer component (Billboard LOD level). Typically a single GameObject has three or four Mesh LOD levels and one optional Billboard LOD level to represent the same GameObject with decreasing detail in the geometry. More info
See in Glossary” (LOD) and “shader replacement” are two techniques that also build upon subshaders, see Shader LOD and Shader Replacemement for details.
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
{
// a single pass in our subshader
Pass
{
// use fixed function per-vertex lighting
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 fixed-function vertex lighting and sets up basic material for it.
See more complex examples at Surface Shader Examples or Vertex and Fragment Shader Examples.