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Odd (To Me) Behavior Of Normals

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Old Codger:
OK so I am building a SciFi thingy and I want to have a geodesic dome on a planetary surface somewhere. Anim8or will let me build a geodesic type sphere and I can easily cut half off of it. Neat and it looks pretty good.

But then I notice that the resulting mesh is not only symmetrical in "Y" but in "X" and/or "Z" as well. Very nice. I want to add "girders" at the edges of all the faces. So the lazy part of me says "We'll simply keep lopping off half of the mesh until we have a quarter dome. Then we'll put little girders at the edges of the faces and when we have the girders lined up okay, then after a couple of 'mirror' and 'join solids' operations we'll be back to a nice full dome without having had to make all those extra girder thingies." That was the plan so - purely for grins and giggles, I cut away half of a geo sphere and then cut away half of the resulting dome. Then I mirror what is left and join solids. OOPS!!! The normals on the mirrored half are obviously wrong.

What is going on?
I have attached rendered images of the dome at various stages. The file names are fairly self explanatory. The two "mir" images are pre and post "join solids" operation.

johnar:
Hey Old codger.

In object EDIT mode, drag=select the half sphere.
 Now find the INSET button on left toolbar. * (Shift-I)
 Left click on selected half sphere and drag a little to change width of 'girders' (?)
 If that's what you mean by girders.

Edit: If you're happy with that, then i have another suggestion.
 Before creating the girders, (inset tool) hit your selected half sphere using the Shell button. (shortcut 'u')

 That'll give your dome some body.
 Try using shell tool 'after' the 'inset' tool, for a different, perhaps interesting, result.

ENSONIQ5:
Old Codger, there's one more step required after joining the solids.  You'll need to select just the points that are concurrent in both halves, and Edit > Merge Points.  Depending on the size of the sphere you might need to change the merge value, since the points are concurrent going small (eg. .001) should work without dragging non-concurrent points together.  Merging the points will restore the uniformity of the mesh, otherwise even though two dome halves have been joined into one solid they will still be separate meshes.

Steve:
You can also use the clay viewing mode from the top toolbar  to help you see which way the polygons are facing.

Old Codger:
Thanks for the help, guys. ENSONIQ5 told me exactly what I needed to know. Specifically when he wrote, "even though two dome halves have been joined into one solid they will still be separate meshes." (emphasis mine, OC) I did what ENSONIQ5 suggested and VOILA (excuse my French ;) ) the normals are now correct. Never realized that I could have a single "solid" consisting of 2 meshes.

johnar, I'm going to have to play around with your suggestions a bit. Not sure I get what you're saying. What I would ultimately like to do is create a transparent SciFy type geodesic dome with visible girders (triangular cross section with a max of 6 points, 9 vertices and 5 polys per "girder. The girders will overlay the vertices of the main dome. The reason I want to work from 1 quarter of the final dome is because I did something similar MANY years ago and while I have forgotten the details (plus IIRC I was working in a GMAX-based modeler called Flight Simulator Design Studio which did things very differently but which was optimized for modelling airplanes and scenery) but I do recall how much fun it was putting the girders in place. For these girders I'll start with a triangle and extrude it to make a triangular girder. Alternatively I might try faking it by using a transparency map. One thing about being retired and (now) medically home-bound is that I have LOTS of time to experiment. When I get it somewhat ready to show, I'll post some scene renders somewhere.

I want to make this stuff usable for a buddy (who lives half a continent away) who does a web comic. My goal is to become able to make props, buildings and vehicles for him to use to compose scenes in Daz Studio. I dropped some coin upgrading my ancient Dell Optiplex 660 into a somewhat graphics capable system. The basic microP was okay but I doubled the RAM to 16GB (twice what Dell says it can use but online sources said it would work), added a 3TB HDD (in addition to the stock 1TB and dropped in a 256-bit graphics card with 4GB of VRAM which shows up at #5 for value in the top 10 most popular graphics cards (my buddy has 32GB on his system and a graphics card that needs to be liquid cooled). None of that was cheap.

Eventually I may move on to Hexagon for modelling. Maybe. Maybe not. If I can achieve usable results which look good in Daz Studio using Anim8or I might just stay with it.

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