Unity provides a handful of builtin values for your shaders: things like current object's transformation matrices, time etc.
Unity为你在编写shader是提供了少量的内置变量：类似 当前物体的变换矩阵，时间等。
You just use them in ShaderLab like you'd use any other property, the only difference is that you don't have to declare it somewhere - they are "built in".
你只能在ShaderLab中使用它们，就像你使用其他属性一样，唯一不同的是你不能声明内置的变量。
Using them in programmable shaders requires including UnityCG.cginc file.
要用到这些内置变量你必须在你的shader程序中包含UnityCG.cginc file文件。
Transformations 变换
- float4x4 UNITY_MATRIX_MVP
- Current model*view*projection matrix
当前物体*视*投影矩阵。（注：物体矩阵为 本地->世界） - float4x4 UNITY_MATRIX_MV
- Current model*view matrix
当前物体*视矩阵 - float4x4 UNITY_MATRIX_P
- Current projection matrix
当前物体*投影矩阵 - float4x4 UNITY_MATRIX_T_MV
- Transpose of model*view matrix
转置物体*视矩阵 - float4x4 UNITY_MATRIX_IT_MV
- Inverse transpose of model*view matrix
逆转置物体*视矩阵 - float4x4 UNITY_MATRIX_TEXTURE0 to UNITY_MATRIX_TEXTURE3
- Texture transformation matrices
贴图变换矩阵 - float4x4 _Object2World
- Current model matrix
当前物体矩阵 - float4x4 _World2Object
- Inverse of current world matrix
物体矩阵的逆矩阵 - float3 _WorldSpaceCameraPos
- World space position of the camera
世界坐标空间中的摄像机位置 - float4 unity_Scale
- xyz components unused; .w contains scale for uniformly scaled objects.
不适用xyz分量，而是通过w分量包含的缩放值等比缩放物体。
Lighting 光照
In plain ShaderLab, you access the following properties by appending zero at the end: e.g. the light's model*light color is _ModelLightColor0. In Cg shaders, they are exposed as arrays with a single element, so the same in Cg is _ModelLightColor[0].
在纯粹的ShaderLab中，你可以利用下面这些属性，只要在末尾增加一个零数：例如 灯光的物体*灯光颜色是_ModelLightColor0.在Cgshader中这些变量更像是一个包含单一元素的数组。所以在Cg中他们是这样的_ModelLightColor[0];
| Name | Type | Value |
| _ModelLightColor | float4 | Material's Main * Light color 材质的主颜色*灯光颜色 |
| _SpecularLightColor | float4 | Material's Specular * Light color 材质的镜面反射（高光）*灯光颜色。 |
| _ObjectSpaceLightPos | float4 | Light's position in object space. w component is 0 for directional lights, 1 for other lights 物体空间中的灯光为，平行光w分量为零其灯光为1； |
| _Light2World | float4x4 | Light to World space matrix 灯光转世界空间矩阵 |
| _World2Light | float4x4 | World to Light space matrix 世界转灯光空间矩阵 |
| _Object2Light | float4x4 | Object to Light space matrix 物体转灯光空间矩阵 |
Various 变量
- float4 _Time : Time (t/20, t, t*2, t*3), use to animate things inside the shaders
时间： 用于Shasder中可动画的地方。 - float4 _SinTime : Sine of time: (t/8, t/4, t/2, t)
时间的正弦值。 - float4 _CosTime : Cosine of time: (t/8, t/4, t/2, t)
时间的余弦值 - float4 _ProjectionParams : 投影参数
x is 1.0 or -1.0, negative if currently rendering with a flipped projection matrix
x为1.0 或者-1.0如果当前渲染使用的是一个反转的投影矩阵那么为负。
y is camera's near plane y是摄像机的近剪裁平面
z is camera's far plane z是摄像机远剪裁平面
w is 1/FarPlane. w是1/远剪裁平面 - float4 _ScreenParams : 屏幕参数
x is current render target width in pixels x是当前渲染目标在像素值中宽度
y is current render target height in pixels y是当前渲染目标在像素值中的高度
z is 1.0 + 1.0/width z是1.0+1.0/宽度
w is 1.0 + 1.0/height w是1.0+1.0/高度