A rendering method that simultaneously renders both volumetric and polygonal objects is described. Using the method also makes rendering volumetric objects intersected by polygonal ones in the same scheme possible. A ray-volume buffer that stores colors and the transmittance of a ray at each voxel is described. The ray-volume buffer treats volumetric objects as textures. Therefore, the method can be achieved using conventional graphics pipeline by generating a ray-volume in advance. In contrast with the Marching Cube algorithm, the method can generate images that maintain the features of volumetric objects using a small number of surfaces because it renders a volume by using textured boundary surfaces obtained through the volumes.