[UnityShader2]顶点片段着色器实例(四)

原文链接：

http://www.onevcat.com/2013/08/shader-tutorial-2/

http://blog.sina.com.cn/s/blog_89d90b7c0102va4m.html

1.积雪效果

Shader "hongGe/Normal" 
{
    Properties 
    {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _NormalMap("NormalMap",2D) = "Bump"{}
        _SnowLevel ("Snow Level", Range(0,1) ) = 0
        _SnowColor ("Snow Color", Color) = (1,1,1,1)
        _SnowDirection ("Snow Direction", Vector) = (0,1,0)
    }
    SubShader 
    {        
        Pass
        {
            Tags { "LightMode"="ForwardBase" }
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            uniform sampler2D _MainTex;
            uniform sampler2D _NormalMap;
            uniform float _SnowLevel;  
            uniform float4 _SnowColor;  
            uniform float4 _SnowDirection;  
			uniform float4 _LightColor0; 

            struct VertexOutput 
            {
                float4 pos:SV_POSITION;
                float2 uv:TEXCOORD0;
				float3 lightDir:TEXCOORD1;
				float3x3 World2Tangent:TEXCOORD2;
            };

            VertexOutput vert(appdata_tan v)
            {
                VertexOutput o;
                o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
                o.uv = v.texcoord.xy;
				o.lightDir = WorldSpaceLightDir(v.vertex);

				//rotation是模型空间到切线空间
				TANGENT_SPACE_ROTATION;
				o.World2Tangent = mul(rotation,_World2Object);
                return o;
            }

            float4 frag(VertexOutput input):COLOR
            {
				float3 tangentNormal = UnpackNormal(tex2D(_NormalMap, input.uv));
				float3 worldNormal = mul(tangentNormal,input.World2Tangent);

                if(dot(worldNormal, _SnowDirection) > lerp(1,-1,_SnowLevel))
				{
					return _SnowColor;
				}					
				else
				{
					float4 texColor = tex2D(_MainTex,input.uv);
					float3 diffuseReflection = texColor.rgb * _LightColor0.rgb * max(0,dot(worldNormal,input.lightDir));
					return float4(diffuseReflection,1);  
				}					
            }
            ENDCG
        }        
    } 
    FallBack "Diffuse"
}

2.捕捉纹理(整个屏幕的纹理)

Shader "hongGe/GrabTexture" 
{
    Properties 
    {
    }
    SubShader 
    {
		// 在所有不透明对象之后绘制自己，更加靠近屏幕
		Tags{"Queue"="Transparent"}
		// 通道1：捕捉屏幕内容放到_GrabTexture纹理中
		GrabPass{}
		
		// 通道2：设置材质         
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
			sampler2D _GrabTexture;

            struct VertexOutput 
            {
                float4 pos:SV_POSITION;
                float2 uv:TEXCOORD0;
            };

            VertexOutput vert(appdata_base v)
            {
                VertexOutput o;
				o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
                o.uv = v.texcoord.xy;

                return o;
            }

            float4 frag(VertexOutput input):COLOR
            {
				//可能要根据情况对uv坐标进行一些修改
				half4 texCol = tex2D(_GrabTexture,float2(input.uv.x , 1-input.uv.y));	
                return texCol;				
            }
            ENDCG
        }        
    } 
    FallBack "Diffuse"
}

前：

后：

3.捕捉纹理(被遮挡的纹理)

Shader "hongGe/GrabTexture" 
{
    Properties 
    {
    }
    SubShader 
    {
		// 在所有不透明对象之后绘制自己，更加靠近屏幕
		Tags{"Queue"="Transparent"}
		// 通道1：捕捉屏幕内容放到_GrabTexture纹理中
		GrabPass{}
		
		// 通道2：设置材质         
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
			sampler2D _GrabTexture;

            struct VertexOutput 
            {
                float4 pos:SV_POSITION;
                float2 uv:TEXCOORD0;
            };

            VertexOutput vert(appdata_base v)
            {
                VertexOutput o;
                o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
				float2 screenUV = ComputeGrabScreenPos(o.pos);//计算该模型顶点在屏幕坐标的纹理信息
                o.uv = screenUV;

                return o;
            }

            float4 frag(VertexOutput input):COLOR
            {
				half4 texCol = tex2D(_GrabTexture,input.uv);	
                return 1 - texCol;				
            }
            ENDCG
        }        
    } 
    FallBack "Diffuse"
}