Shader "FluidDynamics/MatRenderer" 
{    
    Properties
    {
        _MainTex ("MainTexture", 2D) = "white" {}
    }
    SubShader 
    {
        Blend SrcAlpha OneMinusSrcAlpha 
        ZWrite Off
        Tags {"Queue" = "Transparent" }
        Pass 
        {
            ZTest LEqual
            CGPROGRAM
            #include "UnityCG.cginc"
            #pragma target 4.5
            #pragma vertex vert
            #pragma fragment frag
            
            StructuredBuffer<float> _Particles;
            StructuredBuffer<float4> _ColourRamp;
            float2 _Size;
            struct v2f 
            {
                float4  pos : SV_POSITION;
                float2  uv : TEXCOORD0;
            };
            v2f vert(appdata_base v)
            {
                v2f OUT;
                OUT.pos = UnityObjectToClipPos(v.vertex);
                OUT.uv = v.texcoord.xy;
                return OUT;
            }			
            float4 frag(v2f IN) : COLOR
            {
                int x = (int)(IN.uv.x*_Size.x);
                int y = (int)(IN.uv.y*_Size.y);		
                return _ColourRamp[clamp(_Particles[y*_Size.x + x], 0.0, 255.0)];
            }			
            ENDCG
        }
    }
    Fallback "Diffuse"
}