My mesh models always look like the back is transparent, and I don't know how to fix them.

[Bailey Serenity]

Hello!  I made a jack-o-lantern in mesh and textured it in PS, but it does not render correctly.  The front "face" shows fine, but the back looks invisible.  This changes as I move the camera so that I can see whatever face is closest to me and not the back.

I'm currently starting a series of mesh tutorials, as I made this baby just as an experiment.  However, can anyone pinpoint something I did wrong with this specific mesh?  I also uploaded a very simple astronaut helmet and had the same issue.

My theory is that my problem has come from cutting holes in a mesh sphere, so that the inside AND outside have to be rendered.  I'm thinking that's a no-no, because the insides does not have the faces,vertices, ect.  "Both the helmet and pumpkin were made from a sphere, and I cut holes into the front (one for a face, the other for a... look out type thing).

Any help you can give would be highly appreciated.  I know I should have watched the videos first, but I really do tend to learn better by jumping in (and then finding out that I have to get out quick, quick, quick!).

Thank you.

[DanielRavenNest Noe]

You did nothing wrong.  Mesh object surfaces are "one sided", meaning they only render from one side.  For most objects it is wasted effort to render the "inside" of an object.  For items like yours that need to be seen from both sides, you need to duplicate the geometry in your 3D program, and flip the triangles (or reverse the normals, which is the same thing) on one copy.  That copy will now render from the inside, but not the outside.

For a more realistic jack-o-lantern what you really want to do is enlarge the outer copy by 5-10%, flip the inner copy, and then join the edges at the openings with some more triangles.  Depending on which 3D program you are using, there are functions like "extrude" or "shell" which can take a zero thickness shape and add thickness to it as a single step.

[Nalates Urriah]

It would be interesting to see the model. 

Daniel is right. An object in SL only renders one side. In Blender and other modeling tools it is possible to see both sides. Those tools render both sides to make working with objects easier. One can even tell 3D systems to render both sides. But, not SL. The SL importer does not import that setting... or ignores it if it does.

Daniel offers a solution. In Blender one can select a set of vertices that need to have both sides visible and extrude and scale them. However, that effectively doubles that section's vertex count.

If looking through carved eyes, one may be able to add just a few triangles inside the pumpkin to provide a backdrop for what one sees. If the top of the jack-o-lantern is off, you may need to duplicate most of the pumpkin for the insides.

 

Fun jack-o-lanterns Google finds.

[Coby Foden]

In Blender 2.59 there is a command "Solidify" which can be used to create thickness to the object. One selects "Solidify", gives thickness and then it's ready. It nicely connects the inner and outer surfaces automatically with additional surfaces as well. Then one just needs to check that all surface normals point to proper direction. Fast and easy.

[hibit Spad]

Have you checked which direction he normals are facing?  Occaisionally Blender will flip normals for no apparent reason.

 

To check nomals hit the N key and you should see a panel open up and scroll down.  There will be a check box to show normals.

 

What you will probably see (unless you have made some changes in your system)  will be some blue lines coming out of the face of the mesh into the direction that it will be seen from. 

 

To change the direction normals are facing look under the mesh menu for the normal submenu or try CTRL N  or shift CTRL N.

 

 

 

[Bailey Serenity]

Thank you so much for your replies.  I am going to read them, try again, and take pictures of my before and after models.  I really appreciate all the kindness and help. 

[Bryce Randt]

"In Blender 2.59 there is a command "Solidify" which can be used to create thickness to the object."

You are an angel. Going to see what it does to weights on rigged bits. 

[Masami Kuramoto]

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Bryce Randt wrote:

"

In Blender 2.59 there is a command "Solidify" which can be used to create thickness to the object."

You are an angel. Going to see what it does to weights on rigged bits. 

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It copies the weights so that both sides deform exactly the same way. It also copies the UV layout. It's ideal to make cloth visible from both sides, but remember to uncheck the "Fill Rim" option if the cloth is thin and does not need the additional faces around the edges.