material {
    name : aoPreview,
    parameters : [
        {
            type : sampler2d,
            name : luma
        },
        {
            type : bool,
            name : grayscale
        }
    ],
    requires : [
        uv0
    ],
    shadingModel : unlit,
    culling : none,
    depthCulling: false
}

fragment {
    void material(inout MaterialInputs material) {
        prepareMaterial(material);
        if (materialParams.grayscale) {
            float L = texture(materialParams_luma, getUV0()).r;
            material.baseColor.rgb = vec3(L);
        } else {
            float3 v = texture(materialParams_luma, getUV0()).rgb;
            material.baseColor.rgb = v * 0.5 + 0.5;
        }
    }
}