Mesh skin weight option turns it transparent

[P4rker Engineer]

Hello! This is going to be my second question thread. I have started blendering around last week and I am trying my best to improve. Actually I have made some cool static meshes and scripted them inworld like into a hoverboard.

 

Anyway, I seemed to be doing ok with static meshes. However, I have recently bought an avatar called "Kemono". This avatar is popular these days. Most clothing and attachments don't tend to fit on these avatars unless they are specificly made or are modifyable ( and you know how to do it). The marketplace has tons of clothing and such, however I wanted to go ahead and make myself a chest armor piece just to learn rigging.

 

The creator of  "Kemono" avatars has provided a download file of the avatar mesh dummy here : https://utilizator404.wordpress.com/downloads/

 

So I downloaded it, opened the one that is for default blender and not avastar. Then I created a very simple chest armor piece.

                     

 

When it was done, I started looking for rigging tutorials. I eventually came across this video : https://www.youtube.com/watch?v=EI0bujHVMPM

                    

After following this video, I uploaded the mesh.

                   

 Now my problem starts here, when I turn "Skin Weights" preview on, parts of the mesh go invisible. Like so:

                   

Now, what happens when the mesh is uploaded is it seems fine untill I wear it. When worn, most parts of it go transparent and you can see through it. Anyway, sorry for the long explanation but I wanted to show my problem clearly. Any help would be appreciated. Thank you! :]

 

             Here is the error in all its full size glory:

             

[Loraan Fierrens]

I'm not sure what this would have to do with turning on Skin Weights necessarily, but that last picture looks like your normals are reversed (the far faces are rendering while the nearer faces like the front are not... if you were to move the camera around to the back a little, the front face would proabably pop into view). Blender renders both sides of a polygon (well, at least in object and edit modes), but Second Life renders only the "front" side of the polygon.

Check in Blender which directions your normals are pointing. In edit mode, bring up the properties panel with the N key, under Mesh Display there are options for showing the normals. You will likely need to reduce the size of the normals because the scale is large compared to the Kemono avatar (I have mine set to 0.10). All the normal lines should be pointing so they are emerging from the front side of the polygon and pointing out (in the case of the front panel of your backpack, the normals should point from the backback more or less forwards).

If this is the problem, this sort of thing happens to me all the time. I usually find that I can correct the problem by being sure to Merge Doubles on the vertexes and then use the Normals Recalculate Outside option (CTRL-N in edit mode). If the normals won't recalculate correctly, check for internal edges (that is an edge that is completely inside the object) or edges with more than two faces. Both situations can happen depending on your building technique and both confuse the normal calculations.

I hope this helps.

[P4rker Engineer]

Thanks, I am looking into it right now. The normals seem like they are facing the right way though:

 

 

I will be trying some mof the techniques that you have mentioned and see if I can fix it. Otherwise I will just be creating another mesh and see at which point it gets bugged out so that I can understand my mistake. By the way like I said, the object is normal untill skinn weight is applied. Then it becomes inverted like that. I know... its weird. Anyway thanks :]

[Windancer Farslider]

Make sure every vertex has a non-zero weighting.

Anything that is rigged but has no weight gets removed when rendered.

Tho it still does look like a normals issue. If you have Generate Normals clicked when uploading, unclick it. Force it to use the normals you have already set.

[P4rker Engineer]

Ok... I completely trashed that armor piece and made another one. The transparency issue was gone, then there was deforming issue. I tried and tried and fixed it (probably). However I do not understand why the rigged things don't appear in positions that they are supposed to! I think I'm down... don't know what to do anymore. Peace, and thanks everyone... for your help.

 PS: Here was a test shirt thing I tried... it was not positioned correctly even though it was in blender...

[Loraan Fierrens]

I got your IM Parker, unfortunately I'm pretty busy in RL today and can't get in-world until late afternoon or early evening.

Looking at your picture, one possibility is that you need to apply scale and rotation to your model in Blender before you export (in Object mode, Object > Apply > Rotation and Scale). I'm not 100% sure what this option is doing mechanically (I think it is pushing the scale and rotation transformation on the object down to all the vertexes in some manner), but what it does operationally is to make it so that your object is considered to be at unit scale and non-rotated in its current state. The reason this is helpful is that several portions of Blender interact oddly with transformations. UV unwrapping gets all kinds of wonky if you haven't applied rotation and scale first, as an example. I don't know for sure, but rigging would probably also have a problem with it. It might also help to try Apply > Location too, for that matter, but I've never tried that or heard that it causes problems.

(Here's a little something on applying transformations): http://blender.stackexchange.com/questions/7298/why-is-it-important-to-apply-transformation

One other possiblity that comes to mind is that when you import something rigged for Kemono you have to be careful to import just the skin weights and not the joint positions or Z offset). Since the Kemono avatar already deforms the joint positions in SL, that's present in the Blender armature you rig against but you don't want it brought over again with your attachment. That said, the problem you see doesn't look like it has to do with the bone offsets, I would expect you to see pinched or distorted shoulders in that case.

[P4rker Engineer]

Ah, thanks for the reply Loraan :]. I have investigated the applies. They are indeed necessary and can help at times, so I tried making something from scratch and applied everything before fitting it to the kemono body. I have also tried some different optinos but these meshes still keep appearing mispositioned.

 

 

 

And no,I am not importing with joints or any Z offset. I only choose skin weights and play with lods settings and thats it. I don't know why I upload these after seeing it misplaced in the preview but I guess I just hope for the best. Anyway thanks again, I'll just keep trying some random things here and there. Maybe one day it will work. :]

[Loraan Fierrens]

Well, good luck and keep at it! I don't know what more to suggest (maybe someone else has some ideas). If you'd like me to take a look at sample blend file, feel free to send me the URL in an IM or something. I can't promise I'll see what is wrong, but I'm happy to be another pair of eyes.

[P4rker Engineer]

Thanks Loraan :]. I would however like to call this problem fixed. I've been trying and talking with people enough to understand that errors will occur on the road, but this time I have fixed it by using different options. Basicly, the transparency issue was fixed by recalculating normals and paying attention to them. Also I took more lessons on weight painting. Then there was the misplacement issue, which was fixed by using different armature options etc.

 

 

So the end result was this. Just a test, to make sure I get the hang of it. It is a basic armor that covers the back and front. For now other than some weighting issues I have not seen any deformations, transparency or misplacement. I will continue on my way to learn more and get better. I would like to thank you Loraan and Windancer. Without your help I couldn't probably figure things out.