Why is texture black?

[Pamela Galli]

I textured some starsin a collage and they come out black, unless I switch to planar, in which case it looks like this:

 

The starts are all UVed, the UV matches the texture, normals are not flipped, there are no doubles, only 4 materials used for the whole collage, a little over 9,000 faces total.

I cant think of any reason for the texture not to apply properly to these stars.

 

Anyone?

 

[Drongle McMahon]

Could it be Multiple UV maps?

[Pamela Galli]

Thank you Drongle, that seems to be it.  I did not understand the other thread, no surprise there. I rarely look at the UV tab/panel, so not sure what is supposed to be there.  I have three UVs, and no idea how they got like that.  My collage has stars, snowflakes, and trees.  In the UV tab I have 3 UVs -- a star UV, a snowflake and star UV, and a tree UV.  This pic shows the second one -- the first one, the star only, is the only UV that does not have the camera grayed out.

What should I do

 

 

[Pamela Galli]

At this point I have three separate UV maps showing in the UV map tab, one for each shape.  Since these are all one object, should I have one UV map showing for them all?  

 

And if so, how did I wind up with three and how do I get just one?

[Drongle McMahon]

I don't know how you got three. Did you start out with them as separate objects? SL will only use one map for one object; so you do have to have all the materials in one UV map. That doesn't mean you have to have the UVs for different materials non-overlapping. They can overlap freely, as they won't be used together. In other words, unwrap each material separately, using the whole UV area for each (and doing any futher overlapping you want, of course). Now when you select everything, the uv edit view will show the overlapping maps, but when you select by material in the 3D view, the uv view will show just the map for that material (as long as synch select is off). I don't know a way to re-order the UV maps in the list. So unless you get the correct mapping in the top one, you will have to delete the others (in a copy, if you still need them). I think Aquila recently did a nice illustration of using one map with overlapping for different materials.

[Pamela Galli]

I always use one map with overlapping materials (when needed).  I must have some preference checked that I did not mean to check.

I guess I will just try starting over -- it is just a simple thing but I just dont seem to be able to get these UV maps to behave normally.

[Pamela Galli]

Okay this is what I did just now:  had three separate meshes -- one star, one snowflake, one tree. Each has a UV map (and different material).  I copied them first, and then joined the copies into one mesh.  That one mesh now has three UV maps.  When I select and edit the whole mesh, only the star UV map shows up in the UV edit window.

I must be doing something different than usual because I join things all the time and I assume wind up with one UV map for one mesh. 

[Pamela Galli]

Finally resorted to the old standby :  exported the three separate objects as .obj, reimported and joined them, voila, one UV map.

No clue what the problem was.

[Pamela Galli]

Update:  Trying to texture part of a floor -- the inworld texture was all messed up, so I checked and sure enough, double UV maps. (The rest of the floor is messed up too but I cant find double UV maps, or any other reason.)

[Pamela Galli]

Is there some kind of setting that would cause Blender to start generating multiple UV Maps? Because I think I may have activated it.

[Drongle McMahon]

I don't know one, but how did those you showed get their names? Maybe there's a clue there?

[Pamela Galli]

One is called UV Map, the other is named whatever the mesh is called.

[Pamela Galli]

I am thinking I just need to reinstall Blender.

[Dree Eames]

The reason you ended up with 3 uv's is because each object had a unique name assigned to their UV when you combined them.  *

I'm guessing as a practice you don't name your uvs and just keep the default "UVMap" name Blender assigns.  When you combine 3 objects made in Blender, each with a default UV name of "UVMap",  Blender just creates a single UV with that name and combines everything together.

Edited to add for clarity:

*If you made and imported those objects with UV names other then "UVMap"  into Blender from another program like Zbrush or Photoshop extended that originating program no doubt assigned those cryptic UV names.

 

[Drongle McMahon]

"The reason you ended up with 3 uv's is because each object had a unique name assigned to their UV when you combined them"

I thought that too, but when I tried it, there was only a single map, with one of the names and the two mappings overlapped. The other name was just lost. I guess it combines maps with the same index in the lists of the joined meshes. So it must be something more than that.

[Dree Eames]

I don't understand: "I guess it combines maps with the same index in the lists of the joined meshes."

Drongle, could you please explain what you mean by index and list?  And which version of Blender are you using.  I'm using 2.69 in case that makes a difference. Perhaps this is a new "feature"?

I confirmed my suspicions about what was causing the extra uvs by actually going through the exercise of combining three different objects with distinctly different uv names and ended up, as I expected, with the single mesh and 3 assigned uvs with all original names retained.

 

 

[Drongle McMahon]

Must be a version thing then. I'm still using 2.66a and got the opposite result. The UV map list is in the "UV Maps" section of the "Object properties" tab (triangle icon) of the "Properties" panel/editor (which I keep on the right). Here's a picture. When I combined two meshes esch with one UV map (different names), the combined mesh had only one map in the list. By "index" I mean the position it comes in the list (which is most likely the order they are in memory). So I am guessing what happens if each mesh had more than one map. I'll try it and add result.

ETA - Yes. With two objects, each with two UV maps, and all four maps with different names, joining them left just two maps with the names from the last selected mesh (ie the one with the brighter selection highlight). The first had both of the first listed maps, superimposed, and the second had both of the second listed maps. So maps with the same index were overlayed/combined.

[Dree Eames]

Thanks very much for explaining that in greater detail.  It is a version thing.  I tested it out in 2.66a which I fortunately hadn't yet deleted from my hard drive.  It appears that, as you described, with version 2.66a the last object added is the UV adopted no matter what order the objects are selected.  And the "active" (last selected) object doesn't actually seem to matter - its all about the position on the list, the top object (last added) is the UV for the combined group.

The behavior of 2.69 is completely different.  And I'm guessing there's some rational behind this, but I can't think what it might be.  It's a big inconvenience for me, however, except I generally just use the default UV name, but I might have a problem for items I bring in from modo, zbrush or PS because each UV has ALL the mesh mapped and the  joined mesh parts are represented as stacked verts on the lower left corner.  At the moment I can't think how to combine the UVs into one map so that each combined mesh part is layed out exactly as it was as a seperate object, except by changing all the uv maps to the same name before joining.

[Pamela Galli]

Thanks Dree and Drongle for figuring out this mystery. :-)  I will be careful to name all my meshes the same thing before joining -- although atm I fail to see the utility of the 2.69 behavior.

[Drongle McMahon]

I can see that causing some problems - have to make sure maps you want combined have the same names before joining (if I understand correctly). It would be nice to have the abilities (a) to move items up and down in the list and (b) to combine selected map with the one below. Maybe we should ask the developers for that?

[Dree Eames]

I think you actually meant to write that you will name the mesh UVs the same thing.  I just mention this for clarity in case it's confusing to newcomers to Blender.  You can't actually give more then one mesh item the same exact name, but more then one mesh can have a UV map with the same name.

 

[Pamela Galli]

Yes, that is what I meant to say :-)

[Dree Eames]

It might be beneficial to ask developers for that capability.  I don't delve enough into that deeper part of Blender to know if it's worth their time.  I remember you helped me with a problem created by the way blender stored mesh data and material assignments of linked objects and how it also affected the LOD meshes derived via copies of the high vertex versions.   I haven't been that actively building in SL for some months now to know if this was resolved in later versions of Blender, but I recall having to go into the .dae file and manually cut and paste things back in the same order.  I'm guessing it was due a the way Blender logged it's data that was inaccessible to the user, perhaps similiar to this case.

[Drongle McMahon]

Materials are now sorted by name during upload, and Gaia had the option to export objects in alphabetical order added to the Blender exporter. So I think the ordering problems can now be avoided without requiring manual editing of the dae file.