
#if !defined(SPRITE_MASK_SHARED)
#define SPRITE_MASK_SHARED


// alpha below which a mask should discard a pixel, thereby preventing the stencil buffer from being marked with the Mask's presence
half  _Cutoff;

TEXTURE2D(_MainTex);
SAMPLER(sampler_MainTex);

struct Attributes
{
    float4 positionOS : POSITION;
    half2  texcoord : TEXCOORD0;
};

struct Varyings
{
    float4 positionCS : SV_POSITION;
    half2  uv : TEXCOORD0;
};

Varyings MaskRenderingVertex(Attributes input)
{
    Varyings output;

    output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
    output.uv = input.texcoord;

    return output;
}

half4 MaskRenderingFragment(Varyings input) : SV_Target
{
    half4 c = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
    // for masks: discard pixel if alpha falls below MaskingCutoff
    clip(c.a - _Cutoff);

    return half4(1, 1, 1, 0.2);
}

#endif
<URP>/Shaders/2D/Include/SpriteMaskShared.hlsl full source
