Unity 写一个火焰shader

好的，以下是一个简单的基于Unity的火焰shader示例代码：

Shader "Custom/Fire" {
    Properties {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", Color) = (1,1,1,1)
        _Speed ("Speed", Range(0,5)) = 1
        _Power ("Power", Range(0,5)) = 1
        _Distortion ("Distortion", Range(0,1)) = 0.2
        _Mask ("Mask", 2D) = "white" {}
    }

    SubShader {
        Tags {"Queue"="Transparent" "RenderType"="Transparent"}

        CGPROGRAM
        #pragma surface surf Standard
        #pragma target 3.0

        sampler2D _MainTex;
        sampler2D _Mask;
        float4 _Color;
        float _Speed;
        float _Power;
        float _Distortion;

        struct Input {
            float2 uv_MainTex;
            float2 uv_Mask;
            float3 worldPos;
            float3 worldNormal;
            float3 worldRefl;
        };

        void surf (Input IN, inout SurfaceOutputStandard o) {
            float2 mask = tex2D(_Mask, IN.uv_Mask).rg;
            float2 distortion = (mask - 0.5) * _Distortion * _Power;
            float2 noise1 = tex2D(_MainTex, IN.uv_MainTex + distortion * _Speed).rg;
            float2 noise2 = tex2D(_MainTex, IN.uv_MainTex + distortion * _Speed * 2).rg;
            float2 noise3 = tex2D(_MainTex, IN.uv_MainTex + distortion * _Speed * 3).rg;
            float2 noise4 = tex2D(_MainTex, IN.uv_MainTex + distortion * _Speed * 4).rg;
            float2 noise = (noise1 + noise2 + noise3 + noise4) / 4;

            o.Albedo = _Color.rgb * (1 - mask.r);
            o.Metallic = 0;
            o.Smoothness = 1;
            o.Normal = UnpackNormal(tex2D(_MainTex, IN.uv_MainTex + distortion * _Speed), 0);
            o.Emission = _Power * (noise.r + noise.g) / 2;
        }
        ENDCG
    }
    FallBack "Diffuse"
}

这个shader使用了一个噪波纹理和一个掩码纹理来创建火焰效果。可以通过调整_Speed、_Power和_Distortion属性来控制火焰的速度、强度和扭曲程度。同时，也可以通过_Color属性来改变火焰的颜色。最后，这个shader会将火焰的亮度作为自发光来渲染。