Built-in macros

Unity defines several preprocessor macros when compiling Shader programs.

Target platform

Macro:	Target platform:
SHADER_API_D3D11	Direct3D 11
SHADER_API_GLCORE	Desktop OpenGL “core” (GL 3/4)
SHADER_API_GLES3	OpenGL ES 3.0/3.1
SHADER_API_METAL	iOS/Mac Metal
SHADER_API_VULKAN	Vulkan
SHADER_API_D3D11_9X	Direct3D 11 “feature level 9.x” target for Universal Windows PlatformAn IAP feature that supports Microsoft’s In App Purchase simulator, which allows you to test IAP purchase flows on devices before publishing your application. More info See in Glossary
SHADER_API_DESKTOP	Windows, Mac and Linux desktop platforms, WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. The Unity WebGL build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. More info See in Glossary
SHADER_API_MOBILE	iOS and Android mobile platforms, tvOS

Additionally, SHADER_TARGET_GLSL is defined when the target shading language is GLSL (always true for OpenGL/GLES platforms).

Shader target model

SHADER_TARGET is defined to a numeric value that matches the ShaderA program that runs on the GPU. More info
See in Glossary target compilation model (that is, matching #pragma target directive). For example, SHADER_TARGET is 30 when compiling into Shader model 3.0. You can use it in Shader code to do conditional checks. For example:

#if SHADER_TARGET < 30
    // less than Shader model 3.0:
    // very limited Shader capabilities, do some approximation
#else
    // decent capabilities, do a better thing
#endif

Unity version

UNITY_VERSION contains the numeric value of the Unity version. For example, UNITY_VERSION is 202030 for Unity 2020.3.0. This can be used for version comparisons if you need to write Shaders that use different built-in Shader functionality. For example, a #if UNITY_VERSION >= 202000 preprocessor check only passes on versions 2020 or later.

Shader stage being compiled

Preprocessor macros SHADER_STAGE_VERTEX, SHADER_STAGE_FRAGMENT, SHADER_STAGE_DOMAIN, SHADER_STAGE_HULL, SHADER_STAGE_GEOMETRY, SHADER_STAGE_COMPUTE are defined when compiling each Shader stage. Typically they are useful when sharing Shader code between pixelThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
See in Glossary Shaders and compute Shaders, to handle cases where some things have to be done slightly differently.

Platform difference helpers

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 Shader 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. See in Glossary 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 See in Glossary 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 pixels.
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.

Shadow mapping macros

Declaring and sampling shadow maps can be very different depending on the platform. Unity has several macros to help with this:

Macro:	Use:
UNITY_DECLARE_SHADOWMAP(tex)	Declares a shadowmap Texture variable with name “tex”.
UNITY_SAMPLE_SHADOW(tex,uv)	Samples shadowmap Texture “tex” at given “uv” coordinate (XY components are Texture location, Z component is depth to compare with). Returns single float value with the shadow term in 0..1 range.
UNITY_SAMPLE_SHADOW_PROJ(tex,uv)	Similar to above, but does a projective shadowmap read. “uv” is a float4, all other components are divided by .w for doing the lookup.

NOTE: Not all graphics cards support shadowmaps. Use SystemInfo.SupportsRenderTextureFormat to check for support.

Constant buffer macros

Direct3D 11 groups all Shader variables into “constant buffers”. Most of Unity’s built-in variables are already grouped, but for variables in your own Shaders it might be more optimal to put them into separate constant buffers depending on expected frequency of updates.

Use CBUFFER_START(name) and CBUFFER_END macros for that:

CBUFFER_START(MyRarelyUpdatedVariables)
    float4 _SomeGlobalValue;
CBUFFER_END

If you use a GPU compute buffer or graphics buffer to set the value of the variables, make sure the buffer and the constant buffer have matching data layouts on all graphics APIs you build for. See Using constant buffers with GPU buffers for more information.

Texture/Sampler declaration macros

Usually you would use texture2D in Shader code to declare a Texture and Sampler pair. However on some platforms (such as DX11), Textures and Samplers are separate objects, and maximum possible Sampler count is quite limited. Unity has some macros to declare Textures without Samplers, and to sample a Texture using a Sampler from another Texture. Use this if you end up running into Sampler limits, and you know that several of your Textures can in fact share a Sampler (Samplers define Texture filtering and wrapping modes).

Macro:	Use:
UNITY_DECLARE_TEX2D(name)	Declares a Texture and Sampler pair.
UNITY_DECLARE_TEX2D_NOSAMPLER(name)	Declares a Texture without a Sampler.
UNITY_DECLARE_TEX2DARRAY(name)	Declares a Texture array Sampler variable.
UNITY_SAMPLE_TEX2D(name,uv)	Sample from a Texture and Sampler pair, using given Texture coordinate.
UNITY_SAMPLE_TEX2D_SAMPLER( name,samplername,uv)	Sample from Texture (name), using a Sampler from another Texture (samplername).
UNITY_SAMPLE_TEX2DARRAY(name,uv)	Sample from a Texture array with a float3 UV; the z component of the coordinate is array element index.
UNITY_SAMPLE_TEX2DARRAY_LOD(name,uv,lod)	Sample from a Texture array with an explicit mipmap level.

For more information, see documentation on Sampler States.

Surface Shader pass indicators

When Surface ShadersA streamlined way of writing shaders for the Built-in Render Pipeline. More info
See in Glossary are compiled, they generate a lot of code for various passes to do lighting. When compiling each pass, one of the following macros is defined:

Macro:	Use:
UNITY_PASS_FORWARDBASE	Forward renderingA rendering path that renders each object in one or more passes, depending on lights that affect the object. Lights themselves are also treated differently by Forward Rendering, depending on their settings and intensity. More info See in Glossary base pass (main directional light, lightmaps, SH).
UNITY_PASS_FORWARDADD	Forward rendering additive pass (one light per pass).
UNITY_PASS_DEFERRED	Deferred shadingA rendering path in the Built-in Render Pipeline that places no limit on the number of Lights that can affect a GameObject. All Lights are evaluated per-pixel, which means that they all interact correctly with normal maps and so on. Additionally, all Lights can have cookies and shadows. More info See in Glossary pass (renders G-buffer).
UNITY_PASS_SHADOWCASTER	Shadow caster and depth Texture rendering pass.

Disable Auto-Upgrade

UNITY_SHADER_NO_UPGRADE allows you to disable Unity from automatically upgrading or modifying your shader file.

Depth Texture helper macros

Most of the time, Depth Texture are used to render Depth from the CameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary. The UnityCG.cginc include file contains some macros to deal with the above complexity in this case:

• UNITY_TRANSFER_DEPTH(o): computes eye space depth of the vertex and outputs it in o (which must be a float2). Use it in a vertex program when rendering into a depth texture. On platforms with native depth textures this macro does nothing at all, because Z buffer value is rendered implicitly.
• UNITY_OUTPUT_DEPTH(i): returns eye space depth from i (which must be a float2). Use it in a fragment program when rendering into a depth texture. On platforms with native depth textures this macro always returns zero, because Z buffer value is rendered implicitly.
• COMPUTE_EYEDEPTH(i): computes eye space depth of the vertex and outputs it in o. Use it in a vertex program when not rendering into a depth texture.
• DECODE_EYEDEPTH(i)/LinearEyeDepth(i): given high precision value from depth texture i, returns corresponding eye space depth.
• Linear01Depth(i): given high precision value from depth texture i, returns corresponding linear depth in range between 0 and 1.

Note: On DX11/12 and Metal, the Z buffer range is 1–0 and UNITY_REVERSED_Z is defined. On other platforms, the range is 0–1.

For example, this shader would render depth of its GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary:

Shader "Render Depth" {
    SubShader {
        Tags { "RenderType"="Opaque" }
        Pass {
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct v2f {
                float4 pos : SV_POSITION;
                float2 depth : TEXCOORD0;
            };

            v2f vert (appdata_base v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                UNITY_TRANSFER_DEPTH(o.depth);
                return o;
            }

            half4 frag(v2f i) : SV_Target {
                UNITY_OUTPUT_DEPTH(i.depth);
            }
            ENDCG
        }
    }
}