This paper describes a fast algorithm for the volume conversion and rendering of CSG models constructed from both geometric and volumetric primitives. Using 3D texture mapping and frame buffer pixel operations, the algorithm can interactively generate a binary volume of the CSG model. The result can be used for volume rendering and other applications. Boolean operations are implicitly computed by a Point-Classification Map, and implemented by a hardware assisted frame buffer pixel map. The algorithm can be applied to any regions of interest of the model, thus provides a multi-resolution rendering solution through dynamic voxelization of the viewing regions. Since no pre-processing is required for any change of the CSG tree, it can be used as an effective rendering tool in a volumetric CSG modeling environment.