Version: Unity 6.1 Alpha (6000.1)
Language : English
Branch based on shader model
Branch based on Unity version

Branch based on platform features

Direct use of these platform macros is discouraged, as they don’t always contribute to the future-proofing of your code. For example, if you’re writing a ShaderA program that runs on the GPU. More info
See in Glossary
that checks for D3D11, you may want to ensure that, in the future, the check is extended to include Vulkan. Instead, Unity defines several helper macros (in HLSLSupport.cginc):

Macro: Use:
UNITY_BRANCH Add this before conditional statements to tell the compiler that this should be compiled into an actual branch. Expands to [branch] when on HLSL platforms.
UNITY_FLATTEN Add this before conditional statements to tell the compiler that this should be flattened to avoid an actual branch instruction. Expands to [flatten] when on HLSL platforms.
UNITY_NO_SCREENSPACE_SHADOWS Defined on platforms that do not use cascaded screenspace shadowmaps (mobile platforms).
UNITY_NO_LINEAR_COLORSPACE Defined on platforms that do not support Linear color space (mobile platforms).
UNITY_NO_RGBM Defined on platforms where RGBM compressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
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for lightmapsA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
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is not used (mobile platforms).
UNITY_NO_DXT5nm Defined on platforms that do not use DXT5nm normal-map compression (mobile platforms).
UNITY_FRAMEBUFFER_FETCH_AVAILABLE Defined on platforms where “framebuffer color fetch” functionality can be available (generally iOS platforms).
UNITY_USE_RGBA_FOR_POINT_SHADOWS Defined on platforms where point light shadowmaps use RGBA Textures with encoded depth (other platforms use single-channel floating point Textures).
UNITY_ATTEN_CHANNEL Defines which channel of light attenuation Texture contains the data; used in per-pixel lighting code. Defined to either ‘r’ or ‘a’.
UNITY_HALF_TEXEL_OFFSET Defined on platforms that need a half-texel offset adjustment in mapping texels to pixelsThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
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.
UNITY_UV_STARTS_AT_TOP Always defined with value of 1 or 0. A value of 1 is on platforms where Texture V coordinate is 0 at the “top” of the Texture. Direct3D-like platforms use value of 1; OpenGL-like platforms use value of 0.
UNITY_MIGHT_NOT_HAVE_DEPTH_Texture Defined if a platform might emulate shadow maps or depth Textures by manually rendering depth into a Texture.
UNITY_PROJ_COORD(a) Given a 4-component vector, this returns a Texture coordinate suitable for projected Texture reads. On most platforms this returns the given value directly.
UNITY_NEAR_CLIP_VALUE Defined to the value of near clipping planeA plane that limits how far or close a camera can see from its current position. A camera’s viewable range is between the far and near clipping planes. See far clipping plane and near clipping plane. More info
See in Glossary
. Direct3D-like platforms use 1.0 while OpenGL-like platforms use –1.0.
UNITY_VPOS_TYPE Defines the data type required for pixel position input (VPOS): float2 on D3D9, float4 elsewhere.
UNITY_CAN_COMPILE_TESSELLATION Defined when the Shader compiler “understands” the tessellation Shader HLSL syntax (currently only D3D11).
UNITY_INITIALIZE_OUTPUT(type,name) Initializes the variable name of given type to zero.
UNITY_COMPILER_HLSL, UNITY_COMPILER_HLSL2GLSL, UNITY_COMPILER_CG Indicates which Shader compiler is being used to compile Shaders. See documentation on Shader compilation for more details. Use this if you run into very specific Shader syntax handling differences between the compilers, and want to write different code for each compiler.
  • UNITY_REVERSED_Z - defined on plaftorms using reverse Z buffer. Stored Z values are in the range 1..0 instead of 0..1.

Additional resources

Branch based on shader model
Branch based on Unity version