Direct3D 10: vertex texture fetch rate

Vertex Texture Fetch tests measure the speed of many vertex texture fetches. These tests are essentially similar, and the correlation of their results in Earth and Waves tests must also be similar. Both tests use displacement mapping based on texture fetches. The only major difference is that the Waves test uses conditional branches, while the Earth test does not.

Let's analyze the first test (Earth) in Effect detail Low mode:

Judging by our previous reviews, this test may be affected by texturing speed and by memory bandwidth. However, performance of the new card from AMD at various frequencies does not make it clear. Another candidate to be crossed out from our list of synthetic tests?

Let's not jump at conclusions, there is still a small difference between the cards. The HD 5870 is slightly slower than the GTX 285 in the easy mode, but it's faster in the heavy mode. They are generally on a par. The HD 4890 is not much slower either. Only the dual-GPU cards with AFR take the lead. Let's take a look at results of this test with more texture lookups:

The situation has changed only a little, we can see it in slightly worse results of all cards. The HD 5870 is outperformed by the dual-GPU cards in all modes and by NVIDIA GeForce GTX 285 in the easy mode. Judging by results, memory bandwidth is important, but only in the easy mode. Performance is limited by something else in other modes.

Let's have a look at results of the second vertex texture fetch test. The Waves test executes fewer texture lookups, but it uses conditional branches. The number of bilinear texture lookups in this case reaches 14 (Effect detail Low) or 24 (Effect detail High) per each vertex. Geometry complexity changes just like in the previous test.

Waves test results resemble what we saw last time. AMD products get a bigger advantage here. The HD 5870 almost catches up with the dual-GPU NVIDIA GeForce GTX 295 now, being traditionally defeated only in the easy mode. The new RADEON HD 5800 card does not outperform the prev-gen single-GPU model very much, but it still does. Let's analyze the second modification of the test:

There are almost no changes, although AMD results grow even better versus NVIDIA performance as complexity grows. GeForce GTX 285 is outperformed by the RADEON HD 5870 again. And the latter again fares on a par with the GTX 295. And only the HD 4870 X2 is somewhere far ahead. However, VTF tests in RightMark 2.0 cannot show differences between such powerful solutions anymore either. Alas, their results are practically useless now. Something must be done with this situation.

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