alpha bigger than diffuse/normal

rollin

Hoi!

Does someone know if gameengines can (usually) handle materials where the alpha is, lets say, twice as big as the diffuse and normal map

so:

diffuse: 512^2
normal: 512^2
alpha: 1024^2



thx

vahl

if your alpha is a separate file and your engine allows separate alpha file (UE3 does iirc) then you're fine, but some engines only support alpha from the diffuse alpha channel, so it can be a case by case scenario

Mark Dygert

yup, totally engine dependent. The ones that let you do that normally require it to be the same aspect ratio. So if your diffuse is 512x512 your alpha shouldn't be 1024x2048, one will be scaled to fit the other (normally the alpha will scale to the diffuse) which can cause artifacts when things are mip'ed.

If you're up scaling the alpha to pick up better alpha edge definition it might be better to put the alpha bits (heh) on a seperate smaller texture. Enabling you to have much more definition on your alpha edges but not eating up a huge texture space.

But then again its engine dependent as to what the engine would handle better a big alpha that is mostly black (should compress well but still has a pretty big footprint for such a small amount of info) or new seperate file smaller file where almost every pixel is different. If its a one time case I bet it won't mater that much, but if you're doing it for a bunch of objects (like plants) the extra diffuse texture albeit smaller could be an issue when you start to add them all up.

Its hard to be general about something pretty specific =/

rollin

thx !

thats somehow what i was thinking.. and if the u3 engine can handle things like that i´m fine