Before revision:  This paper proposes a novel reverse tracking method to solve the above challenges, and then, based on it, presents a systematic method for push-pull direct modeling while preserving G1 connections. The developed method has been validated with a series of case studies .
After revision:  This paper proposes a novel reverse tracking method to solve the above challenges, and then, based on it, presents a systematic method for push-pull direct modeling while preserving smooth connections. Case studies and comparisons have been conducted to demonstrate the effectiveness of the method .