Conclusion

Fill-rate is the main weapon in the latest fight for the 3D accelerator customer. Every company is claiming huge numbers to impress the customers. Unfortunately fill-rate has many definitions and that leads to confusion. I defined 3 types : the Theoretical Peak fill-rate (used most), the Texturing fill-rate (used to make bad results sound better) and the Equivalent fill-rate (used for PowerVR). Now all these definitions are based on theoretical data and basically they do not necessarily have a real world meaning. I pointed out 3 mayor reasons why theory and reality can not be equal when you talk about fill-rate.

To clean up this mess and to give fill-rate a Real World meaning I have introduced the Real World fill-rate. This is the fill-rate as it is being measured by the 3D Mark 99 (Max) program. This test takes into account real world problems that a 3D accelerator faces. Based on these Real World numbers I have introduced a fill-rate efficiency number. This number indicates how close an accelerator performs to its theoretical capacity. Most accelerators score Real World values that are about 80% of the theoretically claimed numbers, with one exception PowerVR. The PowerVR accelerators are more efficient due to their different rendering technique.

I hope that this article has convinced you that high fill-rate claims are not always equal to high frame-rates, simply because fill-rate as we know it today is not a Real World number. Even the Real World fill-rate numbers reported by 3D Mark 99 are open for criticism because it is still a artificial benchmark and not a Real Game. Basically the test from 3D Mark doesn't take texture swapping into account since only one single 256 by 256 texture is used, this reduces the risk for Page Breaks and Cache inefficiency. So basically you should reduce the Real World fill-rate numbers even more to get an idea about what is really possible.

If you learn one thing from this article then let it be that theory and reality are different, take everything claimed by a 3D accelerator company with a huge grain of salt. After all they want to convince you that their product is best... and they will do anything to convince you of that. We here at beyond3D will try to figure out what an Accelerator is really worth by looking at their Real World numbers, not just at the theoretically claimed numbers.