Realistic reproduction of spatial reverberation is essential for immersive audio applications, including virtual reality and interactive gaming. While geometrical acoustics methods enable efficient rendering, they do not fully capture wave phenomena such as low-frequency modal behavior and diffraction, which are particularly significant in small spaces. Wave-based simulations provide higher physical accuracy but at substantial computational cost. This paper extends VSVerb, a 4pi sampling reverberator based on virtual sound sources (VS) extracted via sound intensity analysis, to use pressure and three-axis particle velocity computed by a discontinuous Galerkin finite element method (dG-FEM) simulation, enabling reverberation that reflects the wave-based acoustic characteristics of virtual spaces to be generated. Experiments conducted in a university lecture room demonstrate that simulation-based VS distributions and their corresponding impulse responses closely match those derived from actual measurements. ComParison with measured impulse responses and geometrical acoustics ray tracing shows that the proposed method produces room acoustic parameters, including clarity and definition, closer to the measured reference across most metrics and frequency bands. A tendency to underestimate reverberation time was observed, which may be addressed through improved simulation modeling or post-processing. Furthermore, the VS distribution extracted from a single simulation can be adapted to different receiver positions by re-estimating the geometric contribution of each VS, enabling 6DoF navigation support without additional simulation. These results indicate the potential of the proposed framework for wave-based interactive reverberation in virtual spaces.
