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Shader 研究 #9

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
附件是我以前研究 shader 的一些LOG,希望对大家有用.

研究SHADER的目标:

1. 弄懂 Surface shader.
2. 尽可能的挖掘 Vertex Fragment shader 的内容.

Shader语言中嵌入了很多CG(C Grphic)语言的方法,Cg - library:

http://http.developer.nvidia.com/Cg/index_stdlib.html

第一阶段Output:
一个逼真的半透明隐身Shader

Original issue reported on code.google.com by yinyuanq...@gmail.com on 9 Dec 2012 at 9:12

Attachments:

GoogleCodeExporter commented 9 years ago 
http://en.wikipedia.org/wiki/Shader

介绍 Shader 概念的wiki

Original comment by yinyuanq...@gmail.com on 9 Dec 2012 at 9:14

GoogleCodeExporter commented 9 years ago 
我尝试周四前写一个比较接近output 的shader吧

Original comment by lightnin...@gmail.com on 9 Dec 2012 at 9:24

GoogleCodeExporter commented 9 years ago 
Hey Jeffery, 建议学习 Shader 的过程是:

1. 先按照Unity Shader Reference 手册把 Fixed Function Shader 练习一遍
2. 学习 Vertex fragment shader
3. 开始Surface shader

以下是一个 Vertex fragment shader 
,在实验室里面的地砖和墙壁就是用这个SHADER来表现出反射效�
��的:

Asset/Shaders/CustomShaders/GroundPadReflection_Outlined.shader

Shader "Custom/PlanerReflection_Outlined" { //定义SHADER 名字
    Properties { //定义 Shader的外部属性,可以在Inspector 中查看到
        _BaseColor("Base color", Color)= (.5, .5, .5, 1)
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _Cube ("Cube", Cube) = "" {}
        _CubeReflectionFactor("Cube reflection factor", Range(0,1)) = 0.3
        _2DReflect ("2D Reflection", 2D) = "" {}
        _2DReflectionFactor("2D reflection factor", Range(0,1)) = 0.3
        _Normal("Normal", 2D) = "bump" {}
        _OutlineColor ("Outline Color", Color) = (0,0,0,1)
        _Outline ("Outline width", Range (.002, 0.03)) = .005
    }
CGINCLUDE   
#include "UnityCG.cginc"
//定义Vertex 传递给 Fragment的参数
    struct v2f_full
    {
      half4 pos : SV_POSITION;  //Vertex顶点位置
      half2 uv : TEXCOORD0;     //UV帖图坐标
      half3 worldViewDir : TEXCOORD1; //UV贴图坐标1
      half3 tsBase0 : TEXCOORD2;//UV贴图坐标2
      half3 tsBase1 : TEXCOORD3;//UV贴图坐标3
      half3 tsBase2 : TEXCOORD4;//UV贴图坐标4
      #ifdef LIGHTMAP_ON    
      half2 uvLM : TEXCOORD5; //LightMap 贴图坐标, 使用宏定义是因为,如果场景没有应用Lightmap 则不需要使用这个变量
      #endif
      half2 uv2DReflection : TEXCOORD6;//UV贴图坐标6
      float4 color:COLOR;//颜色
    };

//Cg变量,和Properties同名//
     float4 _BaseColor; 
     sampler2D _MainTex;
     samplerCUBE _Cube;
     sampler2D _2DReflect;
     sampler2D _Normal; 
     float _CubeReflectionFactor;
     float _2DReflectionFactor;

     //从AngryBot中抄的,不知道干嘛的// 
     void WriteTangentSpaceData (appdata_full v, out half3 ts0, out half3 ts1, out half3 ts2) {
        TANGENT_SPACE_ROTATION;
        ts0 = mul(rotation, _Object2World[0].xyz * unity_Scale.w);
        ts1 = mul(rotation, _Object2World[1].xyz * unity_Scale.w);
        ts2 = mul(rotation, _Object2World[2].xyz * unity_Scale.w);              
     }
         //从AngryBot中抄的,不知道干嘛的// 
     half2 EthansFakeReflection (half4 vtx) {
        half3 worldSpace = mul(_Object2World, vtx).xyz;
        worldSpace = (-_WorldSpaceCameraPos * 0.6 + worldSpace) * 0.07;
        return worldSpace.xz;
     }
ENDCG 

    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200

        Pass
        {
        Name "TextureReflectionBase"
CGPROGRAM

// Upgrade NOTE: excluded shader from OpenGL ES 2.0 because it does not contain 
a surface program or both vertex and fragment programs.
//#pragma exclude_renderers gles

//指定顶点处理方法叫 vert()
        #pragma vertex vert
//指定Fragment处理方法叫 frag()
        #pragma fragment frag
//指定该Shader编译要求是性能优先
        #pragma fragmentoption ARB_precision_hint_fastest 

        //4个float = r,g,b,alpha,代表颜色
        half4 _MainTex_ST;
        half4 unity_LightmapST;

        //sampler2D 就是Texture, 在CG中一个2维位图的变量类型是sampler2D
        sampler2D unity_Lightmap;

        //这个vert的目的是:
        //1. 把计算主贴图的坐标值 -> o.pos = ....
        //2. 如果有LIGHTMAP , 计算LIGHTMAP的帖图坐标  o.uvLM = .....
        //3. 计算 WorldViewDir ,用于 反射帖图
        //4. 计算 uv2DReflection , 似乎也是用于反射,原理不详
        v2f_full vert(appdata_full v) 
        {
            v2f_full o;
            o.pos = mul (UNITY_MATRIX_MVP, v.vertex);

            o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
            #ifdef LIGHTMAP_ON
            o.uvLM = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
            #endif
            o.worldViewDir = normalize(WorldSpaceViewDir(v.vertex));

            WriteTangentSpaceData(v, o.tsBase0, o.tsBase1, o.tsBase2);  

            o.uv2DReflection = EthansFakeReflection (v.vertex);

            return o; 
        }   

        //这个fragment 的目的是:
        //1. 给OBJECT帖图 (主贴图)  -> fixed4 tex = tex2D (_MainTex, i.uv.xy);
        //2. 计算3D反射帖图 , 3D并不是指图是3D的,而是3D帖图的输入参数不是一个普通的2维帖图,而是一个CUBE MAP,也就是6个面各有一个对应的帖图(6个2D帖图,对应6个面)
        //3. 如果有LIGHTMAP , 计算LIGHTMAP的帖图像素,然后附加在上一个主帖图至上: -> tex.rgb *= lm;
        //4. 计算 2D反射帖图 : tex += refl_2D * _2DReflectionFactor;
        //注意一点: 计算LightMap的时候,用的是乘法,而计算帖图的时候,用的是加法
        //这是因为: 加法永远只会令OBJECT的材质显示更亮, 而乘法可以令OBJECT的材质显示根据LIGHTMAP的数值变暗. 这正是LIGHTMAP的作用所在.
        fixed4 frag (v2f_full i) : COLOR0 
        {
            fixed4 tex = tex2D (_MainTex, i.uv.xy);

            //Cubemap reflection:

            half3 nrml = UnpackNormal(tex2D(_Normal, i.uv.xy));
            half3 bumpedNormal = half3(dot(i.tsBase0,nrml), dot(i.tsBase1,nrml), dot(i.tsBase2,nrml));

            half3 reflectVector = reflect(normalize(-i.worldViewDir.xyz), normalize(bumpedNormal.xyz));

            //tex += refl_3D * tex.a;

            half4 refl_3D = texCUBE(_Cube, (reflectVector)); 
            tex += refl_3D * _CubeReflectionFactor;

            #ifdef LIGHTMAP_ON
            fixed3 lm = DecodeLightmap (tex2D(unity_Lightmap, i.uvLM.xy));
            tex.rgb *= lm;
            #endif

            //2D Reflection:
            fixed4 refl_2D = tex2D (_2DReflect, i.uv2DReflection);
            tex += refl_2D * _2DReflectionFactor;
            tex.rgba *= _BaseColor;
            return tex;

        }

ENDCG
        }

        //这个PASS是用来画外框线的(Outline), 原理没有研究过.
        Pass {
            Name "OUTLINE"
            Tags { "LightMode" = "Always" }
            Cull Front
            ZWrite On
            ColorMask RGB
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM
            #include "UnityCG.cginc"
            #pragma vertex vertOutline
            #pragma fragment fragOutline
            struct appdata {
              float4 vertex : POSITION;
              float3 normal : NORMAL;
            };

            struct v2f {
              float4 pos : POSITION;
              float4 color : COLOR;
            };
            uniform float _Outline;
            uniform float4 _OutlineColor;

            v2f vertOutline(appdata v) {
              v2f o;
              o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
              float3 norm = mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal);
              float2 offset = TransformViewToProjection(norm.xy);
              o.pos.xy += offset * o.pos.z * _Outline;
              o.color = _OutlineColor;
              return o;
            }
            half4 fragOutline(v2f i) :COLOR { return i.color; }
            ENDCG
        }

    } 
    FallBack "Diffuse"
}

Original comment by yinyuanq...@gmail.com on 9 Dec 2012 at 9:50

GoogleCodeExporter commented 9 years ago 
把大概的做好了,在手机上运行似乎还有点瑕疵
脚本的设置见图,附上动画图

Original comment by lightnin...@gmail.com on 14 Dec 2012 at 12:12

Attachments:

GoogleCodeExporter commented 9 years ago 
刚才发的两个GIF可能要下载才能看演示
脚本和shader都在unitypackage里面

Original comment by lightnin...@gmail.com on 14 Dec 2012 at 12:14

GoogleCodeExporter commented 9 years ago 
淡入淡出效果不错,看起来有一种街机的FEEL ~~

Original comment by yinyuanq...@gmail.com on 14 Dec 2012 at 2:36

GoogleCodeExporter commented 9 years ago 
http://unity3d.com/unity/download/archive

URL to download all Unity build-in shader source code.

Original comment by yinyuanq...@gmail.com on 16 Dec 2012 at 2:15

GoogleCodeExporter commented 9 years ago 
bug fixed:
隐形之后,predator的render会先于decal什么的

在subshader里的tags加入
                "Queue" = "Transparent+1" 
就可以了

(详细请见文档http://docs.unity3d.com/Documentation/Components/SL-Subshader
Tags.html,这里贴一段出来
The predefined queues are:

Background - this render queue is rendered before any others. It is used for 
skyboxes and the like.
Geometry (default) - this is used for most objects. Opaque geometry uses this 
queue.
AlphaTest - alpha tested geometry uses this queue. It's a separate queue from 
Geometry one since it's more efficient to render alpha-tested objects after all 
solid ones are drawn.
Transparent - this render queue is rendered after Geometry and AlphaTest, in 
back-to-front order. Anything alpha-blended (i.e. shaders that don't write to 
depth buffer) should go here (glass, particle effects).
Overlay - this render queue is meant for overlay effects. Anything rendered 
last should go here (e.g. lens flares).

Original comment by lightnin...@gmail.com on 15 Jan 2013 at 4:25