Environment Mapped Bump Mapping

What is Environment Mapped Bump Mapping (EMBM)? As taken from our G400 Review:

Instead of manipulating a standalone texture map to make it "look" like it has bumps on it, Environment-Mapped Bump Mapping adds a third texture to the rendering sequence (in cases where both an Environment Map and a Texture Map are present). The third texture, or the bump-map, is nothing more than the basic environment map with bumps and grooves. Since the G400 is capable of single pass multi-texturing (as well as 2 pixels per clock in the event that only a single texture is being processed), the Environment Map and Texture Map are processed first in 1 clock cycle, then the Bump-Map is added on top of them in 1/2 a clock cycle. It's simple addition of textures, unfortunately the added 1/2 clock cycle required by the Bump-Map does tend to slow things down a little.


expend-nobump.jpg (24289 bytes)


expend-bump.jpg (33715 bytes)

Using Rage Software's Expendable, an incredible looking game, there was a noticeable drop in frame rate when Bump Mapping was enabled near points of extensive use of Environment-Mapped Bump Mapping. At 1024 x 768 x 32-bit color & 32-bit Z-buffer on a normal Pentium II 400, the frame rate dropped from extremely fluid to a point where the game was a little choppy. The game was still playable, although be warned that there is a drop in performance. If you look at it from the point of view of the G400 chip itself, it makes sense that there would be a drop in performance as you're making the processor calculate information for another 1/2 clock cycle just so you can look at pretty water - the things we make our computers do ;)

Will Bump Mapping catch on? Considering that the only requirement for a game to support Environment Mapped Bump Mapping is that the developer makes use of DirectX 6 or greater and includes specific support for it (not too complex), don't be too surprised if the market leaves some doors open for G400 users. Hopefully other manufacturers will catch on and we'll see Environment Mapped Bump Mapping catch on big time, it would be sad to lose this kind of quality because of poor market support.

Unfortunately this isn't the case, that one Expendable screen shot caught our attention but since then, there has yet to be a comparable example in the gaming industry. The games that have implemented EMBM haven't done so nearly as well as Rage did with Expendable, so look around at other implementations of EMBM before you make any decisions here.  Dungeon Keeper 2 supports EMBM, and the implementation is very well done, but there are some cases when EMBM is just not that great of an option to have turned on.

Let's hope for Matrox’s sake that things do change, but very few users will be going out and buying G400's simply because Expendable's water has cool looking bumps on it unless more gaming manufacturers start boasting more support for the technology. 

TV-Tuning & DualHead Gaming Performance

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