Particle shader

Shader "Effect/fire" {
Properties {
    _OffsetTex ("Offset Tex", 2D) = "white" {}
    _MainTex("Mask(A) ", 2D) = "white" {}

    _TxtrScale ("Texture scale", Range(0, 4)) = .125
    _TxtrSpeed ("Texture speed", Range(-2, 2)) = .2


    _Brightness ("Brightness", Range(0, 4)) = 1
    _Flatten ("Flatten", Range(1, 10)) = 5.72
    _Gamma ("Gamma", Range(0, 3)) = 1
    _AlphaAdd ("Alpha affect", Range (0, 1)) = .612
    _TxtrMult ("Texture multi", Range (0, 4)) = .5
    _TxtrAdd ("Texture add", Range (-1, .01)) = -.192
}

Category {
    Tags { "Queue"="Transparent+3000" "RenderType"="Transparent" }
    Blend SrcAlpha One
    AlphaTest Greater .01
    Cull Off Lighting Off ZWrite Off

    SubShader {
        Pass {
            Name "BASE"
            Tags { "LightMode" = "Always" }

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0
            #pragma multi_compile_particles
            #pragma multi_compile_fog
            #include "UnityCG.cginc"

            struct appdata_t {
                float4 vertex : POSITION;
                fixed4 color : COLOR;
                float2 texcoord: TEXCOORD0;
                float4 random: TEXCOORD2;
                float4 center: TEXCOORD1;
            };

            struct v2f {
                float4 vertex : POSITION;
                fixed4 color : COLOR;
                float2 uvmain : TEXCOORD0;
                float2 worldPosition: TEXCOORD1;
                float4 random: TEXCOORD3;
                float4 center: TEXCOORD4;
            };

            float _Brightness;
            float _Flatten;
            float _Gamma;
            float _TxtrMult;
            float _TxtrAdd;
            float _TxtrScale;
            float _TxtrSpeed;

            half4 _DisplacementScrollSpeed;
            half4 _Strength;
            half4 _Params;
            float _AlphaAdd;
            float4 _OffsetTex_ST;
            float4 _CellSize;
            sampler2D _OffsetTex;
            sampler2D _MainTex;

        v2f vert (appdata_t v)
        {
            v2f o;
            o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
            o.uvmain = v.texcoord;//TRANSFORM_TEX(v.texcoord, _OffsetTex);
            o.worldPosition = mul(UNITY_MATRIX_T_MV, v.vertex);
            o.color = v.color;
            o.center = v.center;// + _Time.yyyy*_DisplacementScrollSpeed.xyxy;
            o.random = v.random;
            return o;
        }


        float2 quant(float2 f, float2 q ){
            return round(f/q)*q;
        }

        float2 ttex(float2 tex, float4 st) {
            return tex.xy * st.xy + st.zw;
        }

        float2 rotate(float2 original, float angle ){
            angle = angle * 0.01745329252;
            float sinX = sin ( angle );
            float cosX = cos ( angle );
            float2x2 rotationMatrix = float2x2( cosX, -sinX, sinX, cosX);
            return mul(original, rotationMatrix );
        }

        half4 frag( v2f i ) : COLOR
        {
            half2 uv = i.uvmain;

            fixed4 txtr = tex2D(_MainTex, uv);

            uv = i.worldPosition * _TxtrScale
                    - i.center * _TxtrSpeed
                    + i.random.xy;

            fixed offset = tex2D(_OffsetTex, uv).r;

            offset = saturate( offset + (i.color.a-1)*_AlphaAdd + _TxtrAdd);
            float f = exp(_Flatten);
            txtr = clamp(txtr.r * offset * _TxtrMult , 0, 1/f) * f * _Brightness;

            return pow( txtr * i.color, _Gamma);
        }
    ENDCG
    }
}
        // ------------------------------------------------------------------
        // Fallback
        SubShader{
            Blend DstColor Zero
            Pass{
            Name "BASE"
            SetTexture[_MainTex]{ combine texture }
            }
        }
    }
}