Getting Started with Cinema 4D, Part 04: Introduction to Generator Objects - Part 1: Extrude Objects

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Instructor eyedesyn

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In this video, I’m going to show you how you can utilize what’s called Generator Objects to be able to generate custom geometry from existing geometry, or even splines.

In this video, you’ll continue building up your submarine by utilizing what’s called Generator Objects that allow you to generate custom geometry from existing geometry, or even splines, which are C4D’s equivalent of an After Effects or Photoshop Path.

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Primitives can only get you so far when building objects. Now typically, you'll need to create much more custom shapes to build whatever you need to build in 3D. In this video, I'm going to show you how you can utilize what's called Generator Objects to be able to generate custom geometry from either existing geometry or splines. Now, splines are basically Cinema 4D's equivalent of an After Effects or Photoshop Path. So let's dig in here. So let's go ahead and get familiar with these splines. Now, just like we had a menu for all of our primitive objects, we also have a menu for all the different type of spline objects we have. So these are similar to your shape masks and things like that nature inside of After Effects or Photoshop. We also have the Pen Tool which actually functions very similarly to a Pen Tool inside of Adobe products. So let's go ahead and let's build the submarine fins for our little submarine. So what you'll want to do when drawing splines is to choose a flat view. And for most splines I create, I'm going to build them in the front view and this is perfect for our case, it's because we actually want to build the fin right about here. So I'll go ahead, go and maximize my front view, just kind of zoom in here, and I'm just going to build and draw the one top fin using the Pen Tool. So let's go ahead, grab the Pen Tool here, again you're going to hover over the viewport and you're basically going to see that, okay, we've got the Pen Tool loaded up. Now what we can do to create a spline is by either clicking once and you'll see that creates a point, and if I click again, that creates a single spline segment. Now, these are actually creating linear points. Okay? Now if I go ahead and undo that, and if I click and drag instead of just clicking, you see that we'll get the Bezier handles that will then allow me to build a more rounded type of spline. Now I can just go ahead and click on any of these points to edit them. And if I wanted to close this spline, all I need to do is just hover over the first spline point that I created and see that little circle with the closing dot, and you'll see that if I click that, it will then close this spline and I can still edit this once I'm in the Spline Tool here. And this first point was actually a linear point. So if I wanted to change this first linear point to a Bezier or smooth point, all I need to do is go ahead click this point, right-click and go to Soft Tangents. And what that will do is allow me to utilize these Bezier handles. Similarly, I can click on any other point, right-click and change that to Hard Tangents and that will turn into a linear type of spline point. I no longer have those nice Bezier handles to smooth that out. I'm just going to go ahead and right-click, change this to Soft Tangents and just reposition this and basically just edit these points to form a little fin here. Okay. You'll see that I'm working on this single spline object that showed up in our Object Manager. So what I can do before I go any further and keep editing this, I can just double-click on this spline and hit the left arrow key to go all the way to the start of this word, and just name this "Fin Spline." Okay? So again, keeping things named and organized and then I can continue working on this little fin. It looks pretty finny to me. And now what we can do is generate some geometry based off of this spline. Now, to create geometry using a spline, we're going to need what is called a generator object. Now generator objects can be found in this little menu and this menu as well. If I click and hold on this menu, you're going to see a bunch of generator objects that you can tell by just the icon, you kind of get an idea of what each of these generator objects actually do. So let's go ahead, choose the Extrude Object. Now for a generator object to act upon and generate geometry based off of either a spline or another object, you need to place whatever object you want to generate geometry from underneath as a child of that generator object, or in our case, this Fin Spline underneath this Extrude. Now, if you click and drag, you're going to see that we have a couple cursor changes. Now if I bring it up just a little bit, you're going to see an arrow to the left. This actually just doesn't do anything other than move this up and down in our Object Manager. But if I hover over the extrude object and the arrow changes from pointing left to pointing down, watch what happens. This actually makes the Fin Spline a child of this Extrude object. And what you're going to notice is that this actually created and generated geometry based off of that spline. So if I click on this spline, you can see our original spline here and you can see the extruded geometry from that spline. Now, if I click on Extrude and go into the Object tab here, you're going to see just like in the Object tab of many of our primitive objects, we have a bunch of options here as well for our Extrude object. Now, the one thing that is the most important in the Extrude object is how far or how deep the extrude is and the direction in which the object is being extruded. So right now, by default, we have a movement or an extrude of 20 centimeters in the Z. Now, you can tell which centimeter option is which because it's laid out X, Y, and Z. So it's actually extruding the spline out and generating geometry that is 20 centimeters thick. Now we can go ahead and just scrub this and make this a little thinner, maybe 8 centimeters, and you can see we have a nice looking fin here. Now another option that we have in Extrude Objects are the Caps tab. Now, what this allows us to do, if I zoom in on this extrude object, is be able to round out the edges on the start and the end caps. So caps are the front and back faces of an extrude object. And this outer piece right here is the actual extrude geometry. Now, if I go ahead and change this start end caps from Cap to Fillet Cap... now, remember, Fillet is just a fancy term for rounding. If I choose Fillet Cap, you're going to see that we added a bevel to the front or the start of this extrude cap. Now, if I go ahead and go to the End Cap and change it from Cap to Fillet Cap, you're going to see the same thing on this back face of our extrude. Now you're going to see that it's just a nice chisel going on right now because we have just one subdivision between the front face and the actual extrude part of the geometry. And if I wanted to round that out, I could just subdivide this and you're going to see that this is actually smoothing everything out. Same thing with the back geometry of the end cap, if I just add a few steps there, basically, what that's doing is adding more subdivisions and more geometry to smooth out the transition from the extrude to the caps. Now if I go into my Goraud Shading (Lines) display mode, you can actually see those individual steps that we just added. Now, if I take them away, you're going to see that I'm actually adding and removing these subdivisions and therefore smoothing out that geometry. So go ahead, go back to my Goraud Shading so I can actually just see the shading in my scene without the edges. And one thing you're going to notice is that when we added those caps, those Fillet Caps, it's actually made our object thicker. Now, depending on what the radius is, is how big your actual Fillet is or your rounding is. So if I bring both of these radii down to one centimeter, you're going to see that that rounding is much smaller. Now, what I want to do is make this pretty round, so I'm just going to leave this at maybe four centimeters and maybe make this a little less thick. Okay, so maybe bring this down to six centimeters, go back into the Caps, and what we can do to not have our Fillet Caps add on to the thickness of our overall object, because you're going to notice like, toggle on and off, the extrude object by clicking this little checkbox and changing it to an X, that actually deactivates the extruding or the extrude object that acts upon that fin. So notice where the spline is. Okay. Now watch what happens when I turn on that extrude, it actually makes it thicker, it actually grows this geometry out past that initial extrude. Now, if we want to constrain this rounding or the fillets to stay within that original boundary of our spline here, so right here, we can go ahead and choose Constrain. Now watch what happens when I check this on and check this off. Basically, you can see if I, again, toggle on the extrude object on and off, you can see that all the rounding now stays constrained inside of that initial spline that I created. So looking pretty good. You're going to notice a little bit of some geometry intersecting right there. So what I can do is select my spline, and to edit the points, I'm going to make sure I'm in my point mode. Okay. So, right there, click that and just make this little Bezier handles a little bit longer. Okay. And again, you do not want to edit this in this view. Okay. So just like you don't want to just move objects all willy-nilly in your perspective view, you also don't want to edit splines in that view either because look at what happens when I just click and drag. Again, you're moving, indiscriminately, this spline, Bezier handles, in Z space and it's kind of screwing up the actual geometry here. So I'm going to undo that. I just wanted to drive home the point that if you want to edit splines, be sure you're kind of facing it head-on in a front view or a flat view, head-on view, so it's just like you're building a path in a flat space inside of After Effects or Photoshop. It's just easier to draw, easier to manage and add fine-tuning details to your splines. So now you can no longer see that little geometry overlap or polygon overlap that was occurring with our Bezier handles being too short, and now we have this nice rounding. What you're going to notice, though, is when you rotate at certain angles, we get this little seam and this seam is created because, technically, by default, the caps and the rounding and the extrude are not actually joined together. Now, if you wanted to have all of these new cap faces, the Fillet, the rounding and the actual extrude part of the geometry to create a single object and smooth all this out, we can just check on this object and you'll see that we get rid of those seams and this just looks much, much cleaner. Now, one thing you're going to notice, this extrude is not centered. Really, we're just extruding out in one direction and we have this little rounding on the front here, but this is actually dead straight on the zero of our Z depth. Okay? So what it actually did was it extruded out six centimeters in the positive Z so our object is no longer centered. For this new extrude object to be centered, we're going to actually need to divide this movement by two and place that in the Z. So I actually need to move this negative three in the Z and now you'll see that our fin is now centered to the rest of our submarine and looking really nice. So now what I can do is go and double-click on this extrude, rename this to "Fin Extrude" again, keeping things nice and organized, and there's our first fin. Now, how do we easily create another fin? Well, luckily, there is another generator object that allows us to basically flip and mirror an object symmetrically. Now, I showed you that there's actually two generator menus here, one that if you click and hold, we have the Extrude, Loft, Lathe, and Sweep, and then we have this other menu here which has a lot of other type of options. And the one option, the one generator that we want is the Symmetry object. Now when you place the Symmetry object in your scene, again, it acts like any other kind of generator object that for it to work and act upon another object, you need to make that object a child of that generator. So, basically, what I want to do is symmetrically copy the fin extrude object. So, I'm going to go ahead, click and drag and make sure that that arrow is pointing down. And you're going to see that the fin is now symmetrically copied to the left side of our submarine. Now, this is not all right. We don't want this to have little ears, we want this to look like fins. So basically, we need to flip and symmetrically copy the fin extrude in a different direction. So with the Symmetry object selected, I'm going to go into the Object tab, and you're going to see that you can choose the Mirror Plane. So basically, we're going to mirror the fin but in a different direction. So right now, by default, it's set to Z, Y. Now, if we change this to, say, X, Y, you're going to see that this still is not correct. We're not seeing our fin right down here. So let's go ahead and try the X, Z, and you'll see that that's actually the correct plane that we want to flip and mirror the fin on. Okay. So now we have our duplicated fin. Let's go ahead and double-click on the symmetry, type in "Fin." And again, we can make everything named nice and neatly. And what I can do is actually just collapse this whole setup here. So this whole fin setup, I can click on this plus to expand it or click on this to collapse it. So it's just like the little arrows that fold up and down inside of either Photoshop or After Effects. So I'll close that up, make for some more real estate in my Object Manager and voila, we have our fins. Next, I'll show you how we can use a different generator object, the Lathe object to create other elements in our scene.
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