Q re: texturing LODs

[Pamela Galli]

I made a house with a bunch of windows. In one of the windows, the texture of the High LOD is applied to the Medium, or vice versa, which I don't want. In the other windows I can apply different textures to high and medium.  

Any idea how I can get this window to behave?

 

ETA -- As with all the windows I have one material ( "Low LOD)" assigned to the main part of the Med LOD windowframe, and a different material assigned to the main part of the High LOD windowframe. Yet the same texture goes to both. 

[Codewarrior Congrejo]

i can't quite read out how you got your materials set up.

But generally it has to be like this:

- all LODs have to have the exact same amount of materials / and those have to be the same materials.
 
- The area /amount of polygons assigned to a certain material can differ throughout the different LOD levels , as long as the above remains true.

- The texture that is assigned to one material-area / face will stay the same within all LODs. So if the face should show something different on another LOD you will need to move the UV islands of this area to another texture space on the UV  map in the lower LODs in order to have them show a different area on the texture.

When i understand you correctly you have used a 'different' material in the medium LOD model, and another one in the High LOD version of the Model.

To make this work you need at least BOTH materials to be assigned in all versions (all 4 LODs of your model).

You can make 1 hidden polygon somewhere and assign i.e the Low-LOD material to it  in the high LOD model. So it's "there" but not visible. same you will have to do the other way around with the material you used in the HIgh LOD version, you will have to assign it to at least 1 polygon in the other LODs.

As the first rule i wrote on top always has to be kept. All used materials need to be present in all LOD versions.

[Pamela Galli]

Thanks CW.  I do have things set up the way you said -- both high and med LODs have the same materials assigned (otherwise I am allowed to upload the med lod at all). The difference is that on the high LOD, I just assigned one little hidden face the "med lod" material, and on the medium LOD I have most of the window assigned to the "med LOD" material. 

I have done all the windows this same way and they work fine. It's just this one that insists on having the same texture applied to both models the same. I am thinking now maybe it is just some bug and this window will just have to look blotchy when the Med LOD appears. Wah.

 

I do not quite understand this part: "- The texture that is assigned to one material-area / face will stay the same within all LODs. So if the face should show something different on another LOD you will need to move the UV islands of this area to another texture space on the UV  map in the lower LODs in order to have them show a different area on the texture."

I have different textures on high and med models on the other windows. Actually I just put the default blank texture on the med lod since the window is white anyway. 

 

 

[Codewarrior Congrejo]

...I do not quite understand this part: ...

ok let me explain differently: 

- another technique to have parts of the model looking differently in other LODs, without having to assign more material faces and different textures
- is to use a different area on the same texture.

Lets say you have a Window with a wooden cross in the middle and the cross is made of actual geometry in the highest LOD. But for the lowest LOD you just want the whole thing to be 1 quad-polygon with a flat texture. 
Now for optimization, and knowing the viewer / user is going to be so far away when this lowest LOD is reached, it is quite enough to have maybe a 100x100 pixel big area for that where u would have the window and the cross now just as 'Painted' and not as geometry anymore. 

You could paint this 'window' on a 100x100 pixel space i.e. onto the upper right corner or your material's texture, and just move this one Polygon on the UV map to this area.

Means you still have the same material and the same texture, but it shows a 'different' area of the texture when being in  another LOD. This way the people who have to load this model don't need to load a ton of textures. It's one way to keep things optimized =)

 

Now i don't understand one of your sentences: Actually I just put the default blank texture on the med lod since the window is white anyway. 

How do you assign the SL default blank texture to the medium LOD ? The reason why all materials have to be apparent withing all LODs is because you can not select their faces indepently within the LOD versions to assign different textures to a material- so you have to assign their materials already and just define which ploygons are assigned to it wihin a certain LOD.

hm.. if you have set up everything like this and all other windows behave, its hard to say why this one denies to do so as well. Did you try to unassign its material once and just re-assign it, and also the image. And do this for all 4 LODs. It could be that along the way the information got corrupted. 

You could also check in the DAE file (opening it with an editor) if it maybe assigned a wrong texture / material to it. and repair it there. But i prefer fixing it in the file- to have a steady solution.

 

 

 

[Pamela Galli]

Thank you so much CW!  I unassigned then reassigned the LOD material to the MED LOD model and all is well -- yet another thing I would NEVER have thought to try.

 

Genius!  :-)

 

ETA:  Thanks to your help and that of several others in this forum, I am now finished (knock wood) with this house: