Handle unlit materials about cesium-omniverse HOT 1 OPEN

pxr::VtArray<pxr::GfVec3f> getNormalsGlobe(
    const pxr::VtArray<pxr::GfVec3f>& positions,
    const glm::dmat4& localToEcefTransform) {

    const auto ecefToLocalTransform = glm::dmat3(glm::inverse(localToEcefTransform));

    pxr::VtArray<pxr::GfVec3f> normalsUsd(positions.size(), pxr::GfVec3f(0.0f));

    for (size_t i = 0; i < positions.size(); i++) {
        const auto position = UsdUtil::usdToGlmVector(positions[i]);
        const auto positionEcef = glm::dvec3(localToEcefTransform * glm::dvec4(position, 1.0));
        const auto normalEcef = glm::normalize(positionEcef); // geocentric normal, should be geodetic
        const auto normal = ecefToLocalTransform * normalEcef;
        normalsUsd[i] = pxr::GfVec3f(static_cast<float>(normal.x), static_cast<float>(normal.y), static_cast<float>(normal.z));
    }

    return normalsUsd;
}