【Спецэффект 009-Шейдер-Туман】

// 雾特效
Shader "Study/09-FogShader"
{
    
    
    Properties
    {
    
    
        _MainTex ("Texture", 2D) = "white" {
    
    }

        _Color("Fog Color",Color) = (1,1,1,1)
    }
    SubShader
    {
    
    

        Tags{
    
    
            "Queue" = "Transparent"
        }

        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
    
    
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
    
    
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert (appdata v)
            {
    
    
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;
            float3 _Color;

            float rand(float2 p){
    
    
				return frac(sin(dot(p ,float2(12.9898,78.233))) * 43758.5453);
			}

			float noise(float2 x)
			{
    
    
				float2 i = floor(x);
				float2 f = frac(x);

				float a = rand(i);
				float b = rand(i + float2(1.0, 0.0));
				float c = rand(i + float2(0.0, 1.0));
				float d = rand(i + float2(1.0, 1.0));
				float2 u = f * f * f * (f * (f * 6 - 15) + 10);

				float x1 = lerp(a,b,u.x);
				float x2 = lerp(c,d,u.x);
				return lerp(x1,x2,u.y);
			}

			float fbm(float2 x)
			{
    
    
				float scale = 0.5;
				float res = 0;
				float w = 4;
				for(int i=0;i<4;++i)
				{
    
    
					res += noise(x * w);
					w *= 1.5;
				}
				return res * scale;
			}

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                fixed3 col = tex2D(_MainTex, i.uv).rgb;

                // float uv = i.uv;
                // uv.x = uv.x+_Time.x;

                float rb = fbm(i.uv+ _Time.x); // 噪声函数

                fixed3 col_fog = rb*_Color;

                float3 col_out = lerp(col,col_fog,0.2);

                return fixed4(col_out,1);
            }
            ENDCG
        }
    }
}