Normal Map Compression:
When the Radeon X800 and X700 series' were launched, one of the highly touted features was known as '3Dc', which was ATI's new compression format for compressing normal maps.
Far Cry is the first title to feature ATI's new compression technique, and you will see how well this works a little later on. It is important to note that this feature is in the beta stages of development and as a consequence, it is not enabled by default.
To enable this feature, you must first load a level, and then bring down console and type 'r_texnormalmapcompressed 1
'. It initially loads the compressed textures on the fly throughout the level, so it will result in slightly choppy performance when you first run through a level. If you run through the level for a second or third time, you will notice that the choppiness disappears and evens itself out. The option is disabled every time that you change levels, so if you want to make use of this feature, you need to enable it every time you change levels.
The feature works on the GeForceFX, GeForce 6 and Radeon X700/X800 series' graphics cards.
NVIDIA GeForce 6800Ultra
You will be wondering why there are no apparent image quality differences between each of the two frame grabs, there is also no difference in frame rate. This is because the theory behind the type of compression used on the GeForce 6800Ultra, which is known as DXT 5, is supposed to be a 'loss-less' form of compression. It does a very good job of that, as there is no <i>visible</i> image quality degradation.
There is no performance difference on the GeForce 6800Ultra from what we can see, DXT 5 compression doesn't offer quite the same performance characteristics as what 3Dc is capable of, as will become apparent towards the end of this page. We see a single frame per second increase on the minimum frame rate when using normal map compression on this board.
ATI Radeon X800 XT PE
This is our first close look at ATI's new 3Dc technology, and the compression appears to be very good; much like with the GeForce 6800Ultra, we see no visible degradation in image quality. There is a single frame per second difference between the two settings in the 'Dam' level, where we see 35 frames per second with 3Dc enabled.
Despite seeing that single frame per second deficit, 3Dc does wonders for the Radeon X800 XT Platinum Edition's performance, increasing the average frame rate by over 5%. At the same time, we experienced a much higher minimum frame rate during our manual run through - an increase of 3 frames per second aids ATI's best to achieving a considerably smoother gaming experience with 4xAA applied. The increase really shows the possible gains that can be achieved by ATI when using this compression technique - we do wonder how long it will be before NVIDIA implement something similar to this to achieve the same performance gains as a result of no loss in image quality.