Are mipmaps necessary?

bukary on 21/2/2006 at 11:55

What is the difference between the texture with and without mipmaps in TDS? I noticed that only few textures in the original game have mipmaps...

I would create mipmaps, but for some strange reason my GIMP (with the newest Normal Map plugin) does not generate them. :confused:

str8g8 on 21/2/2006 at 12:32

they are generally a good idea, basically they are like LODs for textures. When you save with mip maps multiple versions of the map are saved at progressively smaller and smaller and resolutions, halving each time. For instance, if you had a 1024x1024 texture and saved with 3 mip maps, then the texture would save with the original 1024, plus a 512x512, a 256x256 and a 128x128, all within the same file. The engine then uses the smaller textures when you are far away from it, and swaps in the higher res as you approach - you should never really notice the effect though. Basically they help with frame rate, but increase the overall texture size.

As to why some textures use them and other don't, I'm not sure. With textures that are already quite small, you probably wouldn't bother. Also, it's well known that ISA struggled with the xbox memory limit, maybe they were optimized in favour of getting the overall texture footprint down?

My advice would be to use them on large textures, but you can probably get by without them, esp if your framerate is ok. Are you sure sure that gimp cannot make them? I use photoshop so I'm not much help there, I'm afraid.

bukary on 21/2/2006 at 14:33

Well, GIMP has the option that generates mipmaps, but it seems broken. All mipmaps look the same (completely pink or dark picture).

BTW, I have problems with Photoshop normal maps (described in (http://www.ttlg.com/forums/showthread.php?t=96414) this thread). GIMP's seem to look better in TDS. Could you, please, post the detailed settings of your normal map filter. What setting do you use while making DDS files and their normal maps?

And one more thing: is there any visual difference (while in game) between texture with and without mipmaps? Is it only performance issue? I've made dozens of textures without mipmaps (because I thought I don't need them). Should I remake them?

str8g8 on 21/2/2006 at 16:55

I remember that thread, are you still getting that display problem? It looked to me like a driver problem or something ... if someone downloaded your textures and didn't have that effect that means it's just your setup, right?

Anyway, are you sure mipmaps aren't being created? Maybe gimp isn't displaying them correctly, but the data is ok - test them out in-game and blank mip maps would show up as blank textures from a distance, I think.

Some advice on the nvidia filter - it works on height maps, that is, greyscale bump maps, and is only really good at surface details, don't expect to be able to do the fancy normal maps like AIskins or "DOCwall512B_N.dds". If your bump map isn't any good, no combinations of settings in the filter will make it good, and no one set of settings work in all cases: it is more a case of playing with them until you get the look you want. But for general reference:

Flatten image before using the filter.

wrap=uncheck
Filter type=4 sample (this is just default I think)
Min Z=0, Scale=5 (raising scale to 10 can increase the height of the normal)
Height source=Average RGB
Alternate Conversions=don't use these
Alpha field=height (not sure what this does)

everything else unchecked, mainly I just play with the scale setting

Make full use of the 3d preview though. You can click on the "..." next to decal texture and use the Diffuse map (though it doesn't read dds, annoyingly) then with "use decal texture" ticked when you click 3d preview you get to see how the normal map will look in-game with the colour map :D . In the 3d window you can hit F1 and you will get the keys to rotate around the object, move the light and so on.

When saving as dds you should use DXT1 unless it looks poor (which it often does), in which case use DXT3 (or even DXT5) but these will create bigger files.

Think about how many mip maps would be useful; for instance, if your texture is only 64x64 then 12 levels of mip maps would be a waste of time, 1 or 2 would be enough. I leave all other setting alone.

Hope this helps.

edit: but for mipmaps it is just a performance issue, if your framerate is ok, then maybe you don't need them.

ascottk on 21/2/2006 at 17:25

Quote Posted by bukary

The GIMP dds plugin (not the normal map) has the option of generating mipmaps.

Quote Posted by bukary

Well, GIMP has the option that generates mipmaps, but it seems broken. All mipmaps look the same (completely pink or dark picture).

It depends on the dxt compression. If the dxt supports alpha channels then there should be no problem.

With alpha: dxt3, 5, and uncompressed. There's several options for uncompressed & they do have different qualities to them. The latest dds gimp plugin works very well. Lately I've been using the default but there's RGB8, RGBA8, BGR8 (I used this until the plugin was fixed), ABGR8, R5G6B5, RGBA4, RGB5A1, RGB10A2, L8, and L8A8.

I'd stick with dxt5 (although they get a little blocky) or default uncompressed for normals and DXT3 for diffuse because nvidia has a known rendering bug with DXT1.

STiFU on 22/2/2006 at 12:28

If you want to see the mipmaps effect you can set the systemperformance of your gfx card in the driver under "performance- & qualitysettings" to the lowest entry. (There should be a slider, which must be moved to the left) In germany this setting is called "high performance" on nvidia. ATI has this option too but I can't remember how its name was. Anyway if you go into any game now you will see a clean border between the detailed and the less detailed textures. This is probably the best way to analyse your mipmaps....

bukary on 24/2/2006 at 16:55

Well, I decided not to use mipmaps, because I can not make GIMP generate them and I am not satisfied with Nvidia filter (perhaps I don't know how to set it properly). :(

Here are some of 150 custom textures I introduced into T3Ed (made mostly by Vigil and me):
(http://rapidshare.de/files/14034883/T3Ed_bukary_tex.avi.html)

I hope they will make TDS FM look more like T1/2 FM.

STiFU on 24/2/2006 at 17:05

I think you could do that easily. Just take some 16bit low-res textures without normal or specular map and you're done. ;) No just kidding. I know what you mean and I miss that feeling too...

OrbWeaver on 24/2/2006 at 17:15

It would be interesting to see some performance analyses of T3 with/without mip-maps. They are supposed to be a performance-enhancing measure but this depends on what happens if they are not present. Some games like D3 generate them automatically, although I doubt this is the case with prehistoric Flesh.

ascottk on 24/2/2006 at 17:38

Nice work bukary & Vigil :thumb: I do have some criticisms though. A lot of those textures do not tile very well and the patterns are too obvious. What I suggest is alter the brightness levels around the texture so the patterns are more even. If there's an obvious dark stair pattern then brighten that part of the texture to lessen the effect.