In this paper, a new technique is presented for interactive rendering of caustics fully processed on GPU. Without any pre-computation required, the algorithm can directly render refractive caustics from complex deformable transparent objects onto an opaque receiver surface. By the technique we accurately trace the path of the photons and calculate the energy carried by the photons emitted from the light source, and distribute the energy onto the receiver surface according to Gauss basis function. As a result, photorealistic caustic image is calculated without post-processing and temporal filtering over recent frames. We demonstrate that the interactive caustics can be rendered by our method in real-time for non-uniform deformation of both refractive object and receiver surface, and at the same time, interactive change of light and camera in terms of position and direction could be made.