Making the rounds, and coming to the point.

Alton Brown, of Food Network fame, has made a point repeatedly (and not without reason, I might add) that he loves multipurpose tools, and hates single-purpose ones.  And this is one of the reasons I love what Alton Brown does.  He’s a practical man.  Why expend energy and waste your resources on something that only has one obscure purpose?  I mean, if the purpose is something that you’ll find yourself doing really, really often anyway, that’s one thing, but who really needs the Popiel Inside-The-Egg-Scrambler?  That’s what I have a whisk for.  And the whisk helps me when I make pancake and waffle batter as well.

That bi-rail tool I keep bringing up as it turns out, is good at more than four-sided surfaces.  What if you have a surface that has no clear ‘corners’ to it?  What if you want more than just the outermost edge loop in a shape to be concentric upon itself?  What if you have a shape that comes to a point?  Often muscle groups will do this, and if your modeling a more detailed figure, then you really might need for that muscle group to be well-defined accurately as coming to a triangular point.  I’ll address both these situation in today’s entry.

Here’s the basic setup:  Create a Nurbs circle, duplicate it and scale it up or down to fit inside or outside of the first, your choice.  Selecting a curve point slightly offset from curve origin, detach and eliminate a small arc from the same area on both circles.  Connect the two pairs of endpoints with new EP curves, and snap a few more EP curves spanning between the two pairs at whatever points you find will be key in defining shapes later.  you should have something that looks like a broken wheel with a few spokes.  I’ve made mine so that the two circles are offset in height as well, so it looks more like a cone.

Next, let’s move to the bi-rail-3 tool, as we’ve done before, select our U and V polygon resolution (in this case, the U direction is the one that circumvents the shape while the V direction is the one that is along the radius of the circular shape), enter the tool, select the spokes, hit enter, select the rails, hit enter again, and you get your basic shape.

Note, leave history on here, if you want to use the curves to continue to smoothly shape the polygons before doing your final edits.  Just remember to leave the CV’s that touch other curves alone, or the mesh will disappear, because you’re using history, the curves that define it no longer intersect.


Now there are numerous ways to fill the gap and the hole in middle.  In my case, I used the Bridge tool in the Edit Mesh menu, and a combination of Append to Polygon tool and the Split Polygon tool in the same to create a radial edge flow in one direction, and the desired continuous one in the circumferential direction.

You may or may not have to introduce a new string of edges radiating out from the center in order for the pattern you want to work out evenly, but it likely won’t be more than one.

The result here looks remarkably like a half-dome that you could just as easily produce by taking a stock sphere and cutting it in half.  True, but again, here you can conform the final boundary that your shape will fill before you create the mesh.  Can’t emphasize that enough.  The push-pull-tweak is all but eliminated.  Stock shapes are good for making stock shapes, and little else, I’ve discovered.

Now on to the triangular shape.  We’ll define our boundary with only three curves this time.  I’ve arranged them thus:

Almost like the shape of a deltoid,  right?  What we’re going to attempt here, is to create a situation in which the polys converge to the point on the left side of the shape in the image above, and round out in the other two corners.  To control the direction, make sure the vertex where  you want the polys to converge, has its two respective curves’ direction aimed at each other (either both curves ends at the same point, or the starting point of both curves converge at this point.  (Head to head or tail to tail, never head-to-tail).

Using the Birail-1 tool, go about your business as usual, defining the curve that’s ‘away’ from the convergence point first, then selecting the two birails that form its path.

Be aware that the convergence point only appears to end in one vertex, but there are actually several there, and they should be merged before continuing.

There are any number of ways you can now conduct the flow of poly’s around this kind of object.  I ended up with this configuration with only a few adjustments:

The corner vertices I creased to emphasize the triangular shape.

Big lesson this week: Get to love versatility, and keep an eye out for things that let you achieve it.

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