Writing vertex and fragment shaders

ShaderLab shaders encompass more than just “hardware shaders”. They do many things. They describe properties that are displayed in the Material Inspector, contain multiple shader implementations for different graphics hardware, configure fixed function hardware state and so on. The actual programmable shaders - like vertex and fragment programs - are just a part of the whole ShaderLab’s “shader” concept. Take a look at shader tutorial for a basic introduction. Here we’ll call the low-level hardware shaders shader programs.

If you want to write shaders that interact with lighting, take a look at Surface Shaders documentation. For some examples, take a look at Vertex and Fragment Shader Examples. The rest of this page assumes shaders do not interact with Unity lights (for example special effects, post-processed effects etc.)

Shader programs are written in HLSL language, by embedding “snippets” in the shader text, somewhere inside the Pass command. They usually look like this:

  Pass {
      // ... the usual pass state setup ...
      
      CGPROGRAM
      // compilation directives for this snippet, e.g.:
      #pragma vertex vert
      #pragma fragment frag
      
      // the Cg/HLSL code itself
      
      ENDCG
      // ... the rest of pass setup ...
  }

HLSL snippets

HLSL program snippets are written between CGPROGRAM and ENDCG keywords, or alternatively between HLSLPROGRAM and ENDHLSL. The latter form does not automatically include HLSLSupport and UnityShaderVariables built-in header files.

At the start of the snippet compilation directives can be given as #pragma statements. Directives indicating which shader functions to compile:

#pragma vertex name - compile function name as the vertex shader.
#pragma fragment name - compile function name as the fragment shader.
#pragma geometry name - compile function name as DX10 geometry shader. Having this option automatically turns on #pragma target 4.0, described below.
#pragma hull name - compile function name as DX11 hull shader. Having this option automatically turns on #pragma target 5.0, described below.
#pragma domain name - compile function name as DX11 domain shader. Having this option automatically turns on #pragma target 5.0, described below.

Other compilation directives:

#pragma target name - which shader target to compile to. See Shader Compilation Targets page for details.
#pragma require feature … - fine grained control on which GPU features a shader needs, see Shader Compilation Targets page for details.
#pragma only_renderers space separated names - compile shader only for given renderers. By default shaders are compiled for all renderers. See Renderers below for details.
#pragma exclude_renderers space separated names - do not compile shader for given renderers. By default shaders are compiled for all renderers. See Renderers below for details.
#pragma multi_compile … - for working with multiple shader variants.
#pragma enable_d3d11_debug_symbols - generate debug information for shaders compiled for DirectX 11, this will allow you to debug shaders via Visual Studio 2012 (or higher) Graphics debugger.
#pragma hardware_tier_variants renderer name - generate multiple shader hardware variants of each compiled shader, for each hardware tier that could run the selected renderer. See Renderers below for details.

Each snippet must contain at least a vertex program and a fragment program. Thus #pragma vertex and #pragma fragment directives are required.

Compilation directives that don’t do anything starting with Unity 5.0 and can be safely removed: #pragma glsl, #pragma glsl_no_auto_normalization, #pragma profileoption, #pragma fragmentoption.

Rendering platforms

Unity supports several rendering APIs (e.g. Direct3D 11 and OpenGL), and by default all shader programs are compiled into all supported renderers. You can indicate which renderers to compile to using #pragma only_renderers or #pragma exclude_renderers directives. This is mostly useful in cases where you are explicitly using some shader language features that you know aren’t possible on some platforms. Supported renderer names are:

d3d11 - Direct3D 11/12
glcore - OpenGL 3.x/4.x
gles - OpenGL ES 2.0
gles3 - OpenGL ES 3.x
metal - iOS/Mac Metal
vulkan - Vulkan
d3d11_9x - Direct3D 11 9.x feature level, as commonly used on WSA platforms
xboxone - Xbox One
ps4 - PlayStation 4
psp2 - PlayStation Vita
n3ds - Nintendo 3DS

For example, this line would only compile shader into D3D11 mode:

#pragma only_renderers d3d11

Unity Manual

Writing vertex and fragment shaders

HLSL snippets

Rendering platforms

See Also