Unity provides a handful of built-in global variables for your shadersA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
See in Glossary: things like current object’s transformation matrices, light parameters, current time and so on. You use them in shader programs like any other variable, the only difference is that you don’t have to declare them - they are all declared in UnityShaderVariables.cginc include file that is included automatically.
All these matrices are float4x4 type.
| Name | Value |
| UNITY_MATRIX_MVP | Current model * view * projection matrix. |
| UNITY_MATRIX_MV | Current model * view matrix. |
| UNITY_MATRIX_V | Current view matrix. |
| UNITY_MATRIX_P | Current projection matrix. |
| UNITY_MATRIX_VP | Current view * projection matrix. |
| UNITY_MATRIX_T_MV | Transpose of model * view matrix. |
| UNITY_MATRIX_IT_MV | Inverse transpose of model * view matrix. |
| unity_ObjectToWorld | Current model matrix. |
| unity_WorldToObject | Inverse of current world matrix. |
These variables will correspond to 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 that is renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
See in Glossary. For example during shadowmap rendering,
they will still refer to the Camera component values, and not the “virtual camera” that is used for the shadowmap projection.
| Name | Type | Value |
| _WorldSpaceCameraPos | float3 | World space position of the camera. |
| _ProjectionParams | float4 |
x is 1.0 (or –1.0 if currently rendering with a flipped projection matrix), y is the camera’s near plane, z is the camera’s far plane and w is 1/FarPlane. |
| _ScreenParams | float4 |
x is the width of the camera’s target texture in pixelsThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More infoSee in Glossary, y is the height of the camera’s target texture in pixels, z is 1.0 + 1.0/width and w is 1.0 + 1.0/height. |
| _ZBufferParams | float4 | Used to linearize Z buffer values. x is (1-far/near), y is (far/near), z is (x/far) and w is (y/far). |
| unity_OrthoParams | float4 |
x is orthographic camera’s width, y is orthographic camera’s height, z is unused and w is 1.0 when camera is orthographic, 0.0 when perspective. |
| unity_CameraProjection | float4x4 | Camera’s projection matrix. |
| unity_CameraInvProjection | float4x4 | Inverse of camera’s projection matrix. |
| unity_CameraWorldClipPlanes[6] | float4 | Camera frustum plane world space equations, in this order: left, right, bottom, top, near, far. |
| Name | Type | Value |
| _Time | float4 | Time since level load (t/20, t, t*2, t*3), use to animate things inside the shaders. |
| _SinTime | float4 | Sine of time: (t/8, t/4, t/2, t). |
| _CosTime | float4 | Cosine of time: (t/8, t/4, t/2, t). |
| unity_DeltaTime | float4 | Delta time: (dt, 1/dt, smoothDt, 1/smoothDt). |
Light parameters are passed to shaders in different ways depending on which Rendering PathThe technique Unity uses to render graphics. Choosing a different path affects the performance of your game, and how lighting and shading are calculated. Some paths are more suited to different platforms and hardware than others. More info
See in Glossary is used,
and which LightMode Pass Tag is used in the shader.
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 (ForwardBase and ForwardAdd pass types):
| Name | Type | Value |
| _LightColor0 (declared in UnityLightingCommon.cginc) | fixed4 | Light color. |
| _WorldSpaceLightPos0 | float4 | Directional lights: (world space direction, 0). Other lights: (world space position, 1). |
| _LightMatrix0 (declared in AutoLight.cginc) | float4x4 | World-to-light matrix. Used to sample cookie & attenuation textures. |
| unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0 | float4 | (ForwardBase pass only) world space positions of first four non-important point lights. |
| unity_4LightAtten0 | float4 | (ForwardBase pass only) attenuation factors of first four non-important point lights. |
| unity_LightColor | half4[4] | (ForwardBase pass only) colors of of first four non-important point lights. |
| unity_WorldToShadow | float4x4[4] | World-to-shadow matrices. One matrix for spot lights, up to four for directional light cascades. |
Deferred shading and deferred lighting, used in the lighting pass shader (all declared in UnityDeferredLibrary.cginc):
| Name | Type | Value |
| _LightColor | float4 | Light color. |
| _LightMatrix0 | float4x4 | World-to-light matrix. Used to sample cookie & attenuation textures. |
| unity_WorldToShadow | float4x4[4] | World-to-shadow matrices. One matrix for spot lights, up to four for directional light cascades. |
Spherical harmonics coefficients (used by ambient and light probes) are set up for ForwardBase, PrePassFinal and Deferred
pass types. They contain 3rd order SH to be evaluated by world space normal (see ShadeSH9 from UnityCG.cginc).
The variables are all half4 type, unity_SHAr and similar names.
Vertex-lit rendering (Vertex pass type):
Up to 8 lights are set up for a Vertex pass type; always sorted starting from the brightest one. So if you want
to render objects affected by two lights at once, you can just take first two entries in the arrays. If there are less
lights affecting the object than 8, the rest will have their color set to black.
| Name | Type | Value |
| unity_LightColor | half4[8] | Light colors. |
| unity_LightPosition | float4[8] | View-space light positions. (-direction,0) for directional lights; (position,1) for point/spot lights. |
| unity_LightAtten | half4[8] | Light attenuation factors. x is cos(spotAngle/2) or –1 for non-spot lights; y is 1/cos(spotAngle/4) or 1 for non-spot lights; z is quadratic attenuation; w is squared light range. |
| unity_SpotDirection | float4[8] | View-space spot light positions; (0,0,1,0) for non-spot lights. |
| Name | Type | Value |
| unity_AmbientSky | fixed4 | Sky ambient lighting color in gradient ambient lighting case. |
| unity_AmbientEquator | fixed4 | Equator ambient lighting color in gradient ambient lighting case. |
| unity_AmbientGround | fixed4 | Ground ambient lighting color in gradient ambient lighting case. |
| UNITY_LIGHTMODEL_AMBIENT | fixed4 | Ambient lighting color (sky color in gradient ambient case). Legacy variable. |
| unity_FogColor | fixed4 | Fog color. |
| unity_FogParams | float4 | Parameters for fog calculation: (density / sqrt(ln(2)), density / ln(2), –1/(end-start), end/(end-start)). x is useful for Exp2 fog mode, y for Exp mode, z and w for Linear mode. |
| Name | Type | Value |
| unity_LODFade | float4 | Level-of-detail fade when using LODGroup. x is fade (0..1), y is fade quantized to 16 levels, z and w unused. |
| _TextureSampleAdd | float4 | Set automatically by Unity for UI(User Interface) Allows a user to interact with your application. More info See in Glossary only based on whether the texture being used is in Alpha8 format (the value is set to (1,1,1,0)) or not (the value is set to (0,0,0,0)). |