Wednesday, October 19, 2011

How To Make A Cube:
Episode II: Attack of the Cartesian Plane

So you want to make a pattern from a 3D Model. There are probably several methods for this, but I am going to be doing a direct and very hands on method. This way I can be sure that you’ve got it exactly how you want, without having to learn and wrestle with a new program. Things might be easier if you use something like Paperkura or a CAD program, but I don’t know how to use either. What I do know how to use is graph paper. So we’re going to use that.

First step is to get the cube into a usable .obj form. I’m not going to tell you how to do this. For one, there are many tutorials out there that cover the extraction and conversion of .mdl files from Source games.1 Two, I’ve posted a .obj of the cube on my DA. It’s not textured, so it’s really only useful for making patterns. If you want a textured version, use Google and the Internet to teach yourself how to do it.

It’s like the Matrix, only slower.

Once you’ve got a .obj file, you’re going to need a way to see the values of the vertices. I’ve used a myriad of different 3d programs over the years, but I currently use Silo.2 It’s not too expensive, for a 3d modeling program, and the trial version should give you enough functionality to gather the data we need from this model. Also, it is more intuitive than Blender.3

You can either use sheets of graph paper, or a computer program to plot your data. Since I am not proficient in a CAD program, and drawing programs like GIMP, while serviceable, take forever to plot this data in, we’re going to use graph paper. Just like I did when I made my original patterns.

When you procure your graph paper, make sure it’s marked at 1/10” or 1/5" markings. If you get normal graph paper, that is marked at 1/8" or 1/4" you are going to have to make a lot more calculations and guesses, based of the decimal values of 8ths. This isn’t all that easy, and it isn’t pretty. I know, I used 1/8" graph paper the first time around.4 Also, there are a lot of free graph paper websites out there. The one I used produced graph paper that wasn’t actually spaced correctly, so make sure to measure any Internet graph paper before actually using it.5

So now that we’ve got all of our materials, it’s time to build a cube. Or at least the patterns we’ll need to build a cube. Open up Silo6, and import your .obj cube. Now, you can either center the cube at zero, which is putting the very center of the cube at (0,0,0), or you can center to cube at (20,20,20).

Having the cube at (20,20,20) is nice, because then all your numbers will be positive. Not that it really matters, you certainly leave it at (0,0,0) if you choose. Now you need to pick which face you are going to work off of. I’d recommend orienting the cube so that z is constant, and you are moving in the x/y space. But you don’t have to do this, just make sure that you are plotting your points using the correct coordinate values.

ProTip: Click on this or any other picture for a higher-rez version that it easier to read.

So now you need to plot your points onto your graph paper. Let’s do the large face on the edge as an example. First you need to set up your graph paper. I checked the range of the points on the face that I’m working on, and picked a scaled the worked with that range, and labeled the axes according to that scale. Not all of your pieces will fit on just one normal sheet of graph paper, so you might need to tape a few together in order to have enough space to plot all your data.

Now there are going to be a lot of pictures. Just follow what they say, and in the end you will have two of the twenty pattern pieces you will need to complete this cube. So don’t fall asleep! 7

Now we need to add seam allowance. If you tried to just use this as your pattern, then how would you sew one piece to another?? Answer: Seam allowance! Now standard seam allowance for clothing is 5/8ths of an inch. However, the cube is not clothes, so I’ve done a 1/2 inch seam allowance. This just seemed like a good idea at the time. You can add whatever seam allowance you want when you make your pattern.

That wasn’t so bad! And there’s only only nineteen more to do! Unfortunately, not all patterns are on an plane that allows us to just plot the points on a piece of graph paper. Sometimes we will need to use math. For example, we’ll do the triangle on the edge of the corner.

Now just repeat that for every face. It’s worth noting that I didn’t make a pattern for the long strips that go around the base of the heart button, I just made some calculations and cut strips.8 I also made two strips, one light grey, on dark gray, based on the coloring I observed on the model.

Note the two different colored rings.

I also didn’t worry too much about making deep channels for the pink lines, that you can see from this view. I’m sorry, it would just be too difficult and complicated with a plushie of this size. Also, no one will notice.9 So I just did narrow strips. I did press the seam allowances to the outside instead of each to their own side like I normally would, so they are at least slightly depressed.

Also, the dark grey sections were not cut as one large piece. The side channels were cut separately from the large half-circles. This saved fabric, and made construction easier.10

Now I know I said that programs were harder to use than just graphing everything, however, they are easier for one thing, making circles. Especially big circles. Now you could just jerryrig up a large compass with a bit of string, and in a way that would be easier, but I also wanted to have a good pattern for the heart. Again, you could just sketch that on your circle based on what the looked like, but I am a tad obsessed with things being exactly accurate11 that I wanted to make sure that my heart was as right as possible. So you can use a program, or just draw a large circle on four pieces of paper and sketch a good-looking heart. Then you won’t have to wrestle with gimp to make it print your picture true-to-scale. 12

Now go and finish the rest of those patterns. And then take a nap. Or two or three. Patterning is hard. Once you’re rested, we can move on to constructing the cube.

1 And I don’t want to make one more that will be out of date in six month.
2 My choice of this program has nothing to do with me personally knowing the developer and having received a free copy. Not that that means it's not good. It's actually great. At least for taking data from models. Which is all I used 3d programs for these days.
3Which is so unintuitive I have to relearn the basic controls every time I use it. Sometimes I think that the Open Source movement likes to punish people for using free software by making them so unintuitive, you pay for them in time and brain cells. Which you lose when you smash your head on the desk so hard you pass out. No, I haven’t actually done that. Yet.
4 No, I don't know why. I'm allowed to do stupid thing. Don't judge me. I'm keeping *you* from doing stupid things.
5 I used it for this demo, mostly cause it ment I didn't have to go to the store and buy things. What? I'm a tad lazy. Remeber, we're not judging me cause I'm helpful.
6 Or whatever 3d program you are using. You don't have to be cool if you don't want to.
7 If you one of the two people here for the lolz, just scroll till you see a lot of text again. Talking about making stuff is really dry. And not the funny kind of dry.
8 The pattern would be a long rectangle. ProTip: Rectangles are easier to cut with a quilting ruler and a mat than a paper pattern.
9 Bet you never thought you'd hear me say that. Or read me say that? or.... read my typing... um, you know what I mean...
10 Yes, even I believe in making things easier. Besides, you can kinda see some seam-like coloration where the channels meet the curve. Just check that shot above. In fact, just commit it to memory, we're going to use it again.
11 I'm not always reasonable. Did you forget who you were dealing with?
12 It’s open-source, it knows better than you.

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