OPPORTUNITY, n. A favorable occasion for grasping a disappointment.
[Ambrose Bierce - The Devil's Dictionary]
|Mesh modeling with SubSurfs
This is an introduction to one way of modeling smooth structures, using Blender's Subdivision surfaces. The aim is to create a towerlike structure with windows, creating a rounded shape though still using very few vertices. Using the techniques here described, a lot more interesting objects can be created.
Here, I'll show one way of accomplishing something that can be fairly tricky: a tower-like structure with window holes. Why is this tricky? Because Blender's booleans are, at the time of this writing (Sept 2005), not so very impressive. That means that "punching holes" in an existing mesh can create a rather messy object.
My suggestion is to make the holes while the object is still "flat" and simple, and then find ways of adding depth and roundness without complicating the mesh needlessly.
Working with SubSurfs (as in subdivision surfaces) is, if I have any say in it, the funnest way to model in Blender. Working with meshes can be tedious indeed, since you tend to need an annoying amount of vertices to make something of a bit more complex shape.
Using this fairly straightforward tool, you can make some pretty organic-looking objects with just a few vertices. By jumping in and out of SubSurfs mode, you'll see the actual construction of your object, and how it will appear when rendering.
How will it appear, you ask? Smoother, that's how.
- A basic understanding of Blender and its tools for selection and modeling. E.g. knowing the difference between Edit Mode and Object Mode.
- A version of Blender no earlier than 2.37
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I recommend a "4-up" window layout for this, like most, modeling projects. If you have no idea how to accomplish this, please check out the layout tutorial at Blender.org or download the example Blend file, which will give you a blank stage with a suitable window layout.
(This layout, btw, is my default setting. It can be yours as well. Just open the file and press CTRL+u to make Blender remember this setup.)
If the modeling buttons are not visible, make them so (with the button with a square and four yellow corners.
Now, in top view, hit SPACE and add a Mesh / Tube with 16 segments.
Deselect all vertices (a key). In front view, Box select (b key) the topmost ring of vertices and extrude, move the new vertices some grid units up (hold down CTRL key to constrain movement to grid). Extrude again, and move up.
(Another way to accomplish these segments would be to use the knife tool (k key) and slice the tube twice. Either way is fine.)
Now, we'll make some windows (from whence arrows might be rained down on an attacker, mayhap).
Select the vertices like in the picture.
Press Delete key and choose "faces". This leaves the vertices, so that the entire wall doesn't collapse, but makes holes. Now we have windows.
The tower is still paper thin, though, and would be an easy target for even the weakest of attackers. We'll give it thickness by extruding the walls outwards.
In top view, select all vertices (a key). You may have to press "a" twice, if you had some vertices selected before. Just make'em all yellow, anyway :-)
Press "e" for extrude, and choose "region".
This creates new vertices in the exactly same place as the selected ones. Press Escape key to leave them in their place before moving on to scaling the new vertices.
Switch to scaling mode by pressing "s" right away. Now press "x", to scale only along the x axis. Hold down CTRL while scaling to constrain to grid units. A 1.2 scaling might suffice nicely.
Now press "s" again and then "y" to scale along y axis. Scale as much as before.
(In the lefthand lower corner, you'll see a numeric value representing the amount you're scaling to, where 1.0 is the original size.)
We've basically moved all the new vertices outward to create depth, but not in the Z axis. See?
Now the walls have thickness. They're also pretty "polygony", though. Let's fix that.
Subsurfs create "virtual" segments between the "real" vertices. We don't have to add extra detail and can easily turn this option off to return to our old, boring, object. Select the object and click on "Subsurfs". You'll see how extra geometry seems to be added, but this is merely a calculated geometry.
The main point of SubSurfs is not only to create more segments, but to smoothen the angles between them. This is done automatically, and the effect should be obvious.
The button for this is placed roughly in the middle of the editing buttons screen. Hit it.
The "Subdiv" values let you choose a degree of subdivision, where the lefthand value affects how you see the object in the editor and the righthand value determines how it will be rendered. To avoid confusion, you may want to use the same values in both boxes, but very complex objects combined with a high subdivision preview value may slow the program down. 2 would be a good suggestion for both boxes, in this case.
To soften the edges to make them more easy on the eye, click the "Smooth" button. Also, try clicking on "Auto smooth" to make the smoothing behave a little more wisely.
By now you may start to think that this is useful indeed (hopefully), but that you now have resigned yourself to making an altogether roundish object. Not so. There are ways of making the parts of your choice sharp as a razor's edge. You're still in control, trust me.
Take the windows, for example. A bit on the rounded side, aren't they? How to make them square again without losing all the benefits of subsurfs on the rest of the object?
One way to create "edgier edges" would, of course, be to add more vertices. With less space between vertices, there is less room to make that rounded shape. You could select a row of vertices, duplicate them and move them a bit.
On the other hand, you could make use of the function "Crease subsurf". To make the effect more apparent, change the window viewing mode to "Shaded". Enter edit mode and select all the vertices that make up the window frames. Go to Mesh / Edges / Crease Subsurf (or press SHIFT + e). Now you're creasing. Move the cursor away from the object and observe the effect on the object. The idea should be pretty apparent.
Left click to confirm when you're happy. You can do the same to the base of the tower.
There. A tower, or something like it. In the best of worlds, you'll find much better uses for the principles presented here. In the worst of worlds, you're by now angry and annoyed because nothing worked as I said it would. In that case, sorry!