I spent a little while this morning performing some comparison tests on how texture resolutions impact performance when utilizing alpha maps, ghosting modes and instancing. I was surprised to find some of the results (measured in FPS). In some cases, instancing objects yielded NO performance increase. I also found that utilizing different transparency modes effected performance in various ways as well. The results were a benchmark with 128x128 and 1024x1024 textures and their correlation between different modes. Here are the results:


By alquerian at 2007-06-25

I figured this might prove helpful to some and I am hoping others will add to this, perhaps with benchmarks of other areas of DBP in a controled test environment.

Edit - This was using 100 plains, spaced 1 unit apart, also here is one nifty image that it generated:

Well, much of the slowdown is caused by lots of calls to texture memory and comparisons with what is already there. Instancing won't do much because the screen buffer's read speed isn't what it should be.

That's not always true though. There is a significant difference using transparency modes 3 and 6 with transparency and instancing. There is quite a difference with ghosting in almost every mode. This is very interesting to me, as I would have expected similar performance to the alpha tests.

Here's the troubling thing for me - if you do the same tests without alpha mapping then there is very little difference in performance between texture sizes. With alpha mapping the texture sizes make tons of difference. Shouldn't it use mipmapped versions of the alpha mapped textures and automatically balance the speed? It seems to me that DBP does not use mipmaps with alpha transparency. That's certainly not good.

A fantastic benefit of this test is that I can further optimize Geisha House. I use 512x512 textures for a lot of plants. Like I said earlier, without alpha mapping it wouldn't make any difference, the only concern being video memory. Since it is a concern I'll reduce my texture sizes.

the user, "NeX the Fairly Fast Ferret" really has no idea but his interjection appeared to be clever.