When writing either Surface Shaders or regular Shader Programs, the HLSL source can be compiled into different “shader models”. Higher shader compilation targets allow using more modern GPU functionality, but might make the shader not work on older GPUs or platforms.
Compilation target is indicated by
#pragma target name directive, for example:
#pragma target 3.5
By default, Unity compiles shaders into almost the lowest supported target (“2.5”); in between DirectX shader models 2.0 and 3.0. Some other compilation directives make the shader automatically be compiled into a higher target:
#pragma geometry) set compilation target to
#pragma domain) sets compilation target to
Here is the list of shader models supported, with roughly increasing set of capabilities (and in some cases higher platform/GPU requirements):
Note that all OpenGL-like platforms (including mobile) are treated as “capable of shader model 3.0”. WP8/WinRT platforms (DX11 feature level 9.x) are treated as only capable of shader model 2.5.