Shader "Custom/ParticleAddMulWithZWrite"
{
    Properties
    {
        _TintColor("Tint Color", Color) = (1,1,1,1)
        _MainTex("Particle Texture", 2D) = "white" {}
        _GlowIntensity("Glow Intensity", Range(0,5)) = 2.0
    }
        SubShader
        {
            Tags { "Queue" = "Transparent" "IgnoreProjector" = "true" "RenderType" = "Transparent" }
            Pass
            {
                Tags { "Queue" = "Transparent" "IgnoreProjector" = "true" "RenderType" = "Transparent" }

                ZWrite Off
                ZTest LEqual
                Cull Off

                Blend One One
                ColorMask RGB

                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #include "UnityCG.cginc"

                sampler2D _MainTex;
                fixed4 _TintColor;
                float _GlowIntensity;

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

                struct v2f
                {
                    float4 pos : SV_POSITION;
                    fixed4 color : COLOR;
                    float2 uv : TEXCOORD0;
                };

                v2f vert(appdata v)
                {
                    v2f o;
                    o.pos = UnityObjectToClipPos(v.vertex);
                    fixed4 c = v.color * _TintColor;
                    // 先不乘alpha，因为alpha用亮度计算
                    o.color = c;
                    o.uv = v.uv;
                    return o;
                }

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

                // 计算亮度作为alpha（黑色透明，白色不透明）
                float alpha = texcol.r * 0.3 + texcol.g * 0.59 + texcol.b * 0.11;

                texcol.a = alpha;

                // 预乘alpha
                texcol.rgb *= alpha;

                // 顶点颜色乘以贴图颜色（顶点颜色通常是白色或带调节）
                fixed4 col = texcol * i.color;

                col.rgb *= _GlowIntensity;

                return col;
            }
            ENDCG
        }
        }
}