Loft Generator Demystified: Constructing Objects with the Loft Generator

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  • Duration: 07:35
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In this Video, I will use the Loft Generator to construct a model of a bottle, so you can see how we structure our splines in our scene to achieve predictable results.

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So, it's time to show you how I constructed this bottle. In this empty scene, I'm going to add a circle. Make sure that it's oriented on the XZ, and I'm going to zoom out a bit. Then, I'm going to create a loft generator and make the circle a child of the loft generator. We're going to get this flat surface. Let's make sure the loft generator's caps are set to n-gons, just so that things are nice and clean, and let's begin. Now, you can choose either to make your copies of the circle here because that's what I'm going to do, or make them over here. Just be careful to make sure that you are retaining the proper hierarchy. For example, if I CMD or CTRL drag this to make a copy, then this is fine. The only problem here is that this is the top and this is the bottom, whereas in the 3D space, this is the bottom and this is the top, which means that as long as I'm going in the correct direction , then there won't be any problem. But if I select this one and want to go downwards, so I'm going to make it copy downwards, because it gets added at the end of the hierarchy, it's going to connect to this one, whereas we want it to be above the circle. So, it's good practice, although not necessary to make sure that the way your splines are oriented here, top to bottom, that this is their spatial configuration, just so that you don't get confused trying to find out which one is which. So, let me delete these and let me delete this and go again. So, what do I want to do? Create something above. Make a copy here. So, I'm making the copy above this, so I can drag it upwards. Now, I want to make something beneath the circle. Take this, make a copy. Now, if you drag it down here, it's not going to be a sibling. So, make sure that it's on the same hierarchical level as the rest of the circles, and a child of the loft. Now, I can drag it downwards. And then of course, I can change its scale, I can move it up and down and do whatever I want. Let's go here, make a copy using my CTRL or CMD key, drag it up here, scale it down. Let's pull out a bit, make another copy, use your move tool, move it up, and let's make another copy and move it up a bit more, and there you go. We have a vase instead of a bottle. This is what happens when you're freestyling. Fantastic. So, with circles, it's pretty straightforward what we are trying to do. But what if we're not using circles and we're using different types of objects. So, let me get rid of all these, and revisit the whole thing. So, what I'm going to do now is use N sided polygons. Let's set it to XZ. So, this one has six sides. And I'm going to make it a child of the loft, and then I'm going to make a copy above it, move it above it. Fantastic. And I'm going to make this into a pentagon. Now, you can see already we're getting a few issues. Let me change the lighting, because I don't like how this looks. So, what's happening here is that we have some sort of transition from a pentagon to an hexagon, and it doesn't look that bad. But you can see how polygons are not equally distributed. We have smaller ones, bigger ones. And although you can get away with geometry like this, and it won't render that bad, you'll still get some issues. Let me select this and make sure that we can see all the angles, and you can see we get all sorts of weird artifacts. Now, let's go to the loft object. Let's go to the object tab, and what I want to do is first of all, get rid of subdivision per segment and make this as small as possible, because I'm only interested in polygons that go around. Now, how many mesh subdivisions do we need in order to create a proper transition from six sides to five sides? Here's where a bit of math can do a lot of good work. Now number one, you can always try to put it to organic form, so you'd get equidistant polygons. But in this case, it actually literally cuts corners, because it's trying so hard to create equal distances, that it doesn't retain the shapes of your objects. So, this is a no-no. The other thing you can do is go ahead and increase this to an enormous amount, and although this may look better, it will always cause problems. What if I set this to organic form? Again, you can see we get this clipping. We're not getting our proper silhouettes, the proper profiles. So, there is a way and this is the following. If you take the least common multiplier of the two numbers, so six and five, I'm going to add a link in the description text, telling you what a least common multiplier is for two numbers, but for 5 and for 6, that number is 30. It happens to be the multiple of these two numbers. If I set up my mesh up division to the least common multiplier plus one, then we get a very, very clean transition, and it's a transition that will hold even if we set this to organic form. But because the numbers are correct, it doesn't make a difference between organic form or not. So, this is what you need to do in order to create odd transitions. For example, what if this was a triangle and this is six-sided? Well six is a multiple of six, because one times six is six. And six is a multiple of three, because two times three equals six. So, if I put here, six plus one, that is seven, then we're going to have exactly the same perfect result. So, don't forget that you can use this simple mathematical expression in order to create these seamless transitions between objects. So for example, if I was going to make a triangular shaped bottle and I wanted a round neck, let's make the neck, let's go up. I don't want this to be a triangle. I need this to be a 6 sided polygon or even more, 12 sided polygon and make it smaller. Fantastic. Then, I'm going to make a copy of this and drag it up. Fantastic. Because this is set to 2, but this is set to 12, so I'm going to set this to 12 plus 1, 13, because 12 is the least common multiplier of 12 and 3. Now we get this transition. Now, because everything is correct, if I take this loft and put it under a subdivision surface, you will see that we get these really nice transitions in our shape. At any point, if you make a copy of this close to the previous one, and let's make a copy of this close to the previous one, and make it ever so slightly smaller, you can start sculpting your object to achieve exactly the shape you want. For example, this is the neck. I'm going to make a copy underneath it and drag it slightly lower. And now you can see my transition is much more square. So, as you can see by using these techniques, you can achieve a great degree of modeling freedom, while you still retain a large amount of procedurality.
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