Numerical instability has been a major obstacle to real-time cloth animation. Although the implicit method can make the simulation stable, it is still impossible to generate interactive animation when the geometric model of the virtual cloth is complex enough to represent realistic details. In this paper, we propose efficient animation techniques for the real-time animation of complex deformable objects. The proposed method exploits the stability of the implicit integration in order to use sufficiently large time steps for real-time environments, and obtains the approximate solution with optimized computation and storage. Unlike previous methods for real-time cloth animation, any severe simplification of the problem itself has been avoided in order to produce realistic motions of complex models. In addition, the proposed method deals with instability caused by a force derivative. This problem has been avoided in the previous work with excessive approximation or additional manipulation. However, the technique in this paper avoids instability with a minimal approximation, and does not increase any computational or geometric complexity. The method can be successfully integrated in various real-time environments, such as PC games and VR systems.