Multiple textures on single model
interpolator
whats the impact on final asset for in-game?
All textures I've made so far has been a single sheet. I'm guess multiple textures utilizes the UV channels for different parts of model. Are all game engines able to accept this or is it engine dependent?
thanks!
All textures I've made so far has been a single sheet. I'm guess multiple textures utilizes the UV channels for different parts of model. Are all game engines able to accept this or is it engine dependent?
thanks!
Replies
most will only allow one UV set, or sometimes 2 (diffuse + lightmap). I'd say modern engines give you more control.
however I think most texturing is done with one channel, the others are more for effect stuff, like lightmaps (ambient occlusion...). You may mix detail textures on top, but they could use the same UVs I guess
Eg
the Head uses UV channel 2; and a 512x512 map;
the Torso and Arms use UV Channel 1 and a 1024x1024 map;
the legs use UV channel 3 and a 512x512 map;
I don't see this being done as much with characters as much as environment pieces. whats the rationale behind that?
All the different maps could all be on the same UV channel though.
Usually it's best to keep as many things on a single sheet, since it saves on paging textures in and out of graphics memory - it only has to load one texture for the whole thing.
For example, if you have your character set up as you mentioned earlier, why not just use a 1024 x 1536 map (unusual size, yes, but still a power of 2) and just stack the head and legs 512 maps below, above, or to the side of the main 1024 map, and adjust the UVs accordingly (ie move them up or down by 1-2 UV units).
Back to your original question - there probably isn't *too* much impact if it's just a single character model, but the more you split up textures, the more swapping is likely to take place, so if all the textures are gonna be seen at the same time (like on a character), it's better to put them all on one sheet.
It's also engine dependent, but I'd expect most engines these days to handle multiple textures without problems.
The only reason I think you would need separate textures is if pieces of the models are being swapped out, such was the case with the UT2004 heads. You don't want to load a whole body/head texture if it is going to use only a small piece for the head and reference another totally different texture for the body. Like MoP said if no swapping of pieces will take place, put it all on one, unless you have a really really good excuse not to.
Vig, yeah I forgot about material IDs.
Thanks for clearing things up!
use a 1024 x 1536 map (unusual size, yes, but still a power of 2)
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no, 1024x2048 would be power of 2. Always "double", you cant just sum with another power of 2 number.
Probably be better if the 2 512 pieces were combined into a 1024 x 512, then
http://www.ericchadwick.com/examples/provost/byf1.html
Another reason for a separate material for the head may be that it has an expensive multipass shader, but you don't want that rendering cost to be applied to the rest of the body as well. Still good to share the same UV and texture sheets though, in my experience.
Nice doc, Eric.
and Eric's linked article is a classic, it should be sticky must-read for everyone