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 will assume shaders that do not interact with Unity lights (e.g. special effects, Image Effects etc.)
Shader programs are written in Cg / 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 ...
}
Cg program snippets are written between CGPROGRAM and ENDCG.
At the start of the snippet compilation directives can be given as #pragma statements. Directives indicating which shader functions to compile:
Other compilation directives:
Each snippet must contain at least a vertex program and a fragment program. Thus #pragma vertex and #pragma fragment directives are required.
By default, Unity compiles shaders into roughly shader model 2.0 equivalent. Using #pragma target allows shaders to be compiled into other capability levels. Currently these targets are supported:
#pragma profileoption MaxTexIndirections=256
raises texture indirections limit to 256. Note that some shader model 3.0 features, like derivative instructions, aren’t supported by ARB_vertex_program/ARB_fragment_program. You can use #pragma glsl to translate to GLSL instead which has fewer restrictions.
When compiling to 3.0 or larger target, both vertex and fragment programs need to be present.#pragma target 4.0 - compile to DX10 shader model 4.0. This target is currently only supported by DirectX 11 renderer.
#pragma target 5.0 - compile to DX11 shader model 5.0. This target is currently only supported by DirectX 11 renderer.
Unity supports several rendering APIs (e.g. Direct3D 9 and OpenGL), and by default all shader programs are compiled into for supported renderers. You can indicate which renderers to compile to using #pragma only_renderers or #pragma exclude_renderers directives. This is useful if you know you will only target Mac OS X (where there’s no Direct3D), or only Windows (where Unity defaults to D3D), or if some particular shader is only possible in one renderer and not others. Currently supported renderer names are:
For example, this line would only compile shader into D3D9 mode:
#pragma only_renderers d3d9