Abstract: A shadow generation method using graphics hardware features is presented. It accelerates the shadow computation process and can render it in real-time. The method is image-based, and adopts triple pass rendering. In the third pass, lighting effect of geometric scene is computed,and anti-aliasing techniques used to generate smooth shadow boundaries. The method is implemented in general OpenGL programming and high level GPU programming, with powerful GPU programmable capacity and some useful OpenGL extensions on modern graphics hardware. Experimental results indicate that the 3-pass method can generate shadows with smooth boundaries, while lighting computation makes shadow effects more realistic.