shader內置變量

內置變量都在UnityShaderVariables.cginc文件中聲明

變換矩陣

All these matrices arefloat4x4 type.

Name	Value
UNITY_MATRIX_MVP	Current model * view * projection matrix. 從object space轉到 projection space
UNITY_MATRIX_MV	Current model * view matrix. 從object space轉到camera space
UNITY_MATRIX_V	Current view matrix. 從world space轉到camera space
UNITY_MATRIX_P	Current projection matrix. 從camera space轉到projection space
UNITY_MATRIX_VP	Current view * projection matrix. 從world space轉到projection space
UNITY_MATRIX_T_MV	Transpose of model * view matrix. UNITY_MATRIX_MV 的轉置矩陣
UNITY_MATRIX_IT_MV	Inverse transpose of model * view matrix. UNITY_MATRIX_MV的逆轉置矩陣，法線的矩陣轉換需要用變換矩陣的逆轉置矩陣.
_Object2World	Current model matrix. 從object space轉到world space
_World2Object	Inverse of current world matrix. _Object2World的逆矩陣，從world space 到object space

 

Camera and screen

These variables will correspond to the Camerathat is rendering. 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. 相機的世界坐標
_ProjectionParams	float4	Xis 1.0 (or –1.0 if currently rendering with aflipped projection matrix),yis the camera’s near plane,zis the camera’s far plane andwis 1/FarPlane. x 值是1.0或-1.0（當為反轉的投影矩陣時） y 近截面，z遠截面，w 1/遠截面
_ScreenParams	float4	xis the camera’s render target width in pixels,yis the camera’s render target height in pixels,zis 1.0 + 1.0/width andwis 1.0 + 1.0/height. 屏幕尺寸x寬，y高，z 1+1.0/width,w 1+1.0/height
_ZBufferParams	float4	Used to linearize Z buffer values.xis (1-far/near),yis (far/near),zis (x/far) andwis (y/far). 用於線性化zbuffer
unity_OrthoParams	float4	xis orthographic camera’s width,yis orthographic camera’s height,zis unused andwis 1.0 when camera is orthographic, 0.0 when perspective. 正交攝像機的相關參數,w值1時是正交投影，0時是透視投影
unity_CameraProjection	float4x4	Camera’s projection matrix. 攝像機的投影矩陣
unity_CameraInvProjection	float4x4	Inverse of camera’s projection matrix. 攝像機的投影矩陣的逆矩陣
unity_CameraWorldClipPlanes[6]	float4	Camera frustum plane world space equations, in this order: left, right, bottom, top, near, far. 視錐體的左右下上遠近

 

Time

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). 幀間隔時間

 

Lighting

Light parameters are passed to shaders in differentways depending on which Rendering Pathis used, and which LightModePass Tag is used in the shader.

Forward rendering (ForwardBase andForwardAdd passtypes):

forward渲染的光照變量

Name	Type	Value
_LightColor0(declared in Lighting.cginc)	fixed4	Light color. 光線顏色
_WorldSpaceLightPos0	float4	Directional lights: (world space direction, 0). Other lights: (world space position, 1). World space 光照位置,平行光的w值為0，其他光源的w值為1
_LightMatrix0(declared in AutoLight.cginc)	float4x4	World-to-light matrix. Used to sample cookie & attenuation textures. World space轉到light space矩陣
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.

 

在正向渲染中，影響物體的最亮的幾個光源使用逐像素光照模式。接下來，最多有4個點光源會以逐頂點渲染的方式被計算。其他光源將以球面調和（Spherical Harmonics）的方式進行計算，球面調和技術計算很快但只能得到近似值。

Deferred shading and deferred lighting, usedin the lighting pass shader (all declared in UnityDeferredLibrary.cginc):

延遲光照相關變量

Name	Type	Value
_LightColor	float4	Light color.光照顏色
_LightMatrix0	float4x4	World-to-light matrix. Used to sample cookie & attenuation textures. World space轉到light space矩陣

Spherical harmonics coefficients (used by ambientand light probes) are set up forForwardBase,PrePassFinalandDeferredpasstypes. They contain 3rd order SH to be evaluated by world space normal (seeShadeSH9fromUnityCG.cginc).The variables are all half4 type,unity_SHArandsimilar names.

Vertex-lit rendering (Vertex pass type):                  

Up to 8 lights are set up for aVertexpass type; always sorted starting from the brightest one. So if you wantto render objects affected by two lights at once, you can just take first two entriesin the arrays. If there are less lights affecting the object than 8, the rest willhave their color set to black.

頂點光照相關變量

Name	Type	Value
unity_LightColor	half4[8]	Light colors. 光照顏色
unity_LightPosition	float4[8]	View-space light positions. (-direction,0) for directional lights; (position,1) for point/spot lights. View space光照位置，平行光的w值為0，其他光源的w值為1
unity_LightAtten	half4[8]	Light attenuation factors.xis cos(spotAngle/2) or –1 for non-spot lights;yis 1/cos(spotAngle/4) or 1 for non-spot lights;zis quadratic attenuation;wis squared light range. 光照衰減值
unity_SpotDirection	float4[8]	View-space spot light positions; (0,0,1,0) for non-spot lights. View space聚光燈位置

 

Fog and Ambient

Window > Lighting> Scene 里設置的相應的顏色

Name	Type	Value
UNITY_LIGHTMODEL_AMBIENT	fixed4	Ambient lighting color (Equator ambient in three-color lighting case).
unity_AmbientSky	fixed4	Sky ambient lighting color in three-color lighting case.
unity_AmbientGround	fixed4	Ground ambient lighting color in three-color lighting case.
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.

 

Various

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.

Built-in shader helper functions

其他一些雜七雜八的變量

#pragmatarget 3.0  定義Shader模型為Shader Model 3.0,

 

Image Effect取到depthTexture相關的步驟

GetComponent<Camera>().depthTextureMode=DepthTextureMode.Depth//設置攝像機模式

Shader中聲明  sampler2D _CameraDepthTexture;//深度紋理的聲明

取樣float d = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture,uv) , //0-1越遠越大

 

生成一個深度+法線紋理

GetComponent<Camera>().depthTextureMode=DepthTextureMode.DepthNormals;

Shader中聲明

sampler2D _CameraDepthTexture;//深度紋理的聲明

sampler2D _CameraNormalsTexture;//法線紋理的聲明

用tex2d方法進行法線取樣

 

或者聲明

sampler2D _CameraDepthNormalsTexture.//

用DecodeDepthNormal(tex2D(_CameraDepthNormalsTexture,i.screen.xy), depthValue, normalValues);取得法線跟深度值

 

DecodeDepthNormalto decode depth and normalfrom the encoded pixel value. Returned depth is in 0.1 range.

 

_CameraDepthTexturealways refers to the camera’sprimary depth texture. By contrast, you can use_LastCameraDepthTextureto refer to the last depthtexture rendered by any camera.This couldbe useful for example if you render a half-resolution depth texture in script usinga secondary camera and want to make it available to a post-process shader.

_LastCameraDepthTexture取得最后渲染的深度紋理

 

Texturesize  紋理尺寸獲得

{TextureName}_TexelSize- a float4 property contains texture size information:

xcontains1.0/width

ycontains1.0/height

zcontainswidth

wcontainsheight

例子

uniform float4 _MainTex_TexelSize分別對應Vector4(1 / width, 1 / height, width, height)，

 

Texturetiling & offset 紋理偏移

Materialsoften have Tiling and Offset fields for their texture properties.This information is passed into shaders in a float4 {TextureName}_STproperty:

xcontainsX tiling value

ycontainsY tiling value

zcontainsX offset value

wcontainsY offset value

例：

o.uv =TRANSFORM_TEX(v.texcoord,_MainTex);

相當於

o.uv = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;

o.uv = v.texcoord.xy相當於Tiling為（1，1）Offset為（0，0）