Shader-水流效果

效果图：（贴图类似于泥石流）

代码：

Shader "CookbookShaders/Chapter02/ScrollingUVs"
{
    Properties
    {
        _MainTint("Diffuse Tint", Color) = (1,1,1,1)
        _MainTex("Base (RGB)", 2D) = "white" {}
        _ScrollXSpeed("X Scroll Speed", Range(0, 10)) = 2
        _ScrollYSpeed("Y Scroll Speed", Range(0, 10)) = 2
    }

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

        CGPROGRAM
#pragma surface surf Lambert

    fixed4 _MainTint;
    fixed _ScrollXSpeed;
    fixed _ScrollYSpeed;
    sampler2D _MainTex;

    struct Input
    {
        float2 uv_MainTex;
    };

    void surf(Input IN, inout SurfaceOutput o)
    {
        //Create a seperate variable to store our uvs 
        //before we pass them to the tex2D() function
        fixed2 scrolledUV = IN.uv_MainTex;

        //Create variables that store the individual x and y 
        //components for the uv's scaled by time
        fixed xScrollValue = _ScrollXSpeed * _Time;
        fixed yScrollValue = _ScrollYSpeed * _Time;

        //Apply the final uv offset
        scrolledUV += fixed2(xScrollValue, yScrollValue);

        //Apply textures and tint
        half4 c = tex2D(_MainTex, scrolledUV);
        o.Albedo = c.rgb * _MainTint;
        o.Alpha = c.a;
    }
    ENDCG
    }
        FallBack "Diffuse"
}

注意：

内置方法 _Time

是个4维向量，跟Unity3D中的deltaTime（这是个一维的，数值）不同。

• float4 _Time : Time (t/20, t, t*2, t*3), use to animate things inside the shaders