Multitexturing
The port for game in Duke Nukem 3D (EDuke32) supports multitexturing. The port allows to load not only Diffuse map, but also Bump, Normal, Displacement maps. In port Doomsday Engine of such function is not present. I suggest to enter such innovation as follows: Diffuse map it is designated as STONE4_D.PNG, Bump map - STONE4_B.PNG and Normal map - STONE4_N.PNG or other ways.