Our custom material

card_material.mat

material {
    name : "Card material",
    parameters : [
        {
           type : sampler2d,
           name : baseColorMap
        },
        {
            type : sampler2d,
            name : normalMap
        },
        {
            type : sampler2d,
            name : roughnessMap
        },
        {
            type : sampler2d,
            name : metallicMap
        },
        {
           type : sampler2d,
           name : reflectanceMap
        }
    ],
    requires : [
        uv0
    ],
    shadingModel : lit,
}

fragment {
    void material(inout MaterialInputs material) {
        vec3 normal = texture(materialParams_normalMap, getUV0()).xyz;
        material.normal = normal * 2.0 - 1.0; //bump mapping

        prepareMaterial(material);

        material.baseColor = texture(materialParams_baseColorMap, getUV0());
        material.roughness = texture(materialParams_roughnessMap, getUV0()).r;
        material.metallic = texture(materialParams_metallicMap, getUV0()).r;
        material.reflectance = texture(materialParams_reflectanceMap, getUV0()).r;
    }
}