Here's how I build the planetary interior models. No boolean operations are needed.
1. First, I make a sphere of 1 unit radius, and choose a proper resolution for it. I will need to select some even number of polygons, so I can remove easily 1/8 of the surface, so beware of the resolution of the sphere. In this example, I used a sphere made of 60 longitudinal sections X 40 parallel sections. For a real model made for Celestia, I prefer to use an higher resolution, like 120 x 80 polygons, so the sphere appears smooth at close range) :
2. Then, I select the parts I want to remove (1/8 of the surface) :
3. Erase the polygons :
4. I add an internal sphere to make the core, with the same resolution as the bigger sphere (this isn't necessary, but helps a lot to ease the bridge process described below. See step
7). Of course, all internal parts should be made to scale, knowing that the external sphere has 1 unit radius :
I made a small error in this example, when I selected the polygons before I erased them (see the glitch on top). Be carefull with the selection process.
5. I remove 7/8 of that core, with the same process as
2 and
3 above :
6. I then combine both parts into the same object (your modeler certainly have an option to do this, witout using a boolean function) :
7. I use the "bridge" tool (or "join", depending of your modeler), to joint both parts :
That way, the match should be perfect, and there wont be any hole left, after you separate the parts (for proper texturing).
8. I select the
mantle part (using a "ring select" tool), and separate it from the rest (using the "split" tool of my modeler) :
That way, the match is still perfect with the other piece and I can easily apply a proper texture on the mantle. Now, I have two separate pieces.
9. Selecting the external sphere, I separate it from the internal one ("split" tool again). So I now end with three pieces which are looking like a single piece (perfect match) :
To build the crust, I simply repeat the process described here with several spheres of proper radius, and use the "bridge" tool. After, I simply select a part (the crust, say), and separate it from the rest ("split" tool again, in my modeler), so I can apply a specific texture on it. So, I have a separate piece for the surface, the crust, the mantle and the core. All pieces are matching perfectly (no holes, no defects, and
no invisible polygons), and I can apply a different texture to each one of them.
It's easy, pretty fast, and never give holes or defects, so characteristic of the boolean operations.
Thanks a lot to ElChristou, for holding the pictures on his personal server.
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"
), and then this model would substitute the default Celestia's spheroid in the main solarsys.ssc; thing that is quite deprecable. Without counting the raise of polyhedrons... Mind that in 3ds format Mercury, for example, is just 880 kb. With the Bodyfixed directive one can avoid the text's containers, but for my personal road map, in this add-ons I wish maintain the downward compatibility.
) :
