We present a real-time GPU caustics rendering technique in dynamic scenes under multiple directional lights taking into account light occlusion. Our technique renders caustics cast on receiver objects as well as volumetric caustics. We precompute caustic patterns of caustic objects for several directional lights and store them in caustic images. During the rendering, we interpolate the precomputed caustic patterns based on a given light direction. One of the applications of our technique is to render approximate caustics under environment illumination. To achieve this, we propose an environment cube map segmentation technique which divides cube maps into several light regions with each region is represented using one directional light.