Join EJ Hassenfratz for an in-depth discussion in this video Rubber hose character in Cinema 4D, part of Motion Graphics Weekly.
- [Narrator] Welcome to Motion Graphics Weekly where you up your mo graph knowledge one week at a time. I'm EJ Hassenfratz, let's get our learn on. Rubber hose cell rigging is a very popular form of rigging in After Effects for simplified characters that have very primitive arms and legs that are basically just thick, rounded lines. In this video I'm going to show you how you can create this simple rig inside of Cinema 4D. So let's just set up my scene here.
We have simple capsules for our arms and legs and the one thing I want to note is that on my arms and legs I have a bunch of sub divisions here. You can see that I have a height segment of about eight and this is just so when we actually bend this arm that we have enough geometry where won't have chunky edges. So, just make sure you have enough height segments here. So we have some nice smooth geometry when it bends, and now we can create the bones of our arms and legs using a spline.
So let's start with our arm. Let's just go to our top view here and just zoom in on our arm. So we'll just create a spline using the pen tool and I'll just click and make a point for the shoulder, a point for the elbow, and a point for the hand. You can see that when I made it that it's actually down on the floor. So I'll just move my spline up, so it's aligned to the middle of this arm, or this capsule, and now you can see here's my spline here, looking good.
So basically I want this spline to drive the arm. So what I'll do is first let's keep things organized and just call this the left arm spline and what we'll do to have this spline drive the arm is add a spline wrap to our capsule and what this will do is when we drag our left arm spline into our spline wrap you can see that when we move our spline it's actually wrapped our capsule along that spline and now it can move this around.
So again, when I move this elbow out you can see this chunky edge. It's not very smooth. So I'll just go into my capsule object and increase the height segments, and you'll see that I'll smooth that out. One more thing we can do is actually change these point types. Right now we have a very angular elbow. We can make it a more rounded elbow by choosing a different type of interpolation. So we can choose something like B spline, or akima, but I think I'll go with B spline for now.
So now we have a nice rounded curve for our elbow. So the next thing we want to do is apply IK to our spline, so we can actually use controllers to easily bend and move our arm. To do this I'm going to right click on our left arm spline, go to character tags, and add a IK tag. Now this uses inverse kinematics which is a very common method of animating characters in Cinema 4D or any 3D application and what we're going to do is use the point IK or the points on our spline to create a basic IK rig.
So how the point IK works is you need to define the start point of your spline and the end point of your spline. Now how spline points works is the very first point is point zero, the middle point, or the second point, is point one, and then point two. So, in our IK tag we're going to start at point zero and end at point two, and once you do that you can see that in our front view here we have this little green line that shows the relationship between the first point and our last point.
So if I move this around you can see that we have that relationship there. So to create a control to move the hand area we're going to use a goal. Now a goal controls the hand or wherever our arm is pointing. So I'll add a goal, and you can see that it just comes in as a null, so I'll just rename this left arm goal, and when I move this goal around you can see that it's actually moving the entire arm and when I move it forward it's actually bending the arm as well.
Let me just turn on my capsule again. So you can see this is working like a arm. You can see that when I move my arm up, say we want to do a wave, like we want this character to wave at us. One thing you're going to notice is that the elbow is always pointing backwards, no matter what we do. Now, we need to add another control to be able to control where our elbow is pointing. So to do the full range of our movements you actually need a control for the hand, and a control for the elbow.
So, what the control for the elbow is is called a pole vector. So let's just go ahead and add a pole vector here and here we have it right here, and let's just move it and move it back and move it down and you can see that where we position this pole vector is actually changing where our elbow is pointing. So if we move this pole vector down, move this arm goal, you can see that now we can actually wave because we have our pole vector pointed down, controlling where our elbow is pointing, and our arm goal.
So using poles and goals is a way to animate both arms and legs. So let's go ahead and create more visible controls for our splines. So right now the display is set to dot. Let's change this to a circle, and we'll just increase the radius here, and now we can just go ahead and easily control and grab our pole and our goal by just clicking on these dots here, and we can actually color code these as well by going into our basic tab here, going to use color, changing this to on, and then we can choose a color here.
So maybe some teal, and we can also say make this the icon color in our object manager too. Now you see we just change that color to blue. You can do the same thing for the spline pole. Go to on for the use color, and maybe we'll make this a little pink, and again, use the icon color. So now we have color coded poles, color coded goals. So I'll go ahead and do the same kind of set up for my leg.
All right, so now that we have our leg, pole, spline, and goal all set up as well we can go ahead and group these things together and organize our object manager a little bit here. So let's go ahead and drag our leg spline, leg pole and goal and drag it underneath our left leg group. Then we'll do the same thing and grab our spline, pole, and goal for our left arm, and drag them underneath our left arm group. Now you'll notice that we only have one arm and one leg, so we can easily create our right arm and leg by using a mirror command.
So what we're going to do is select both of the groups that we need to mirror. We're going to go to character mirror tool, and we can actually use this naming function to replace everything that has an L and replace it with R. So just so it doesn't replace the, like the L in goal, or the L in pole, I'm going to say match the case. So it needs to be a capital L, and I'm also going to put a space after it because I have a space after this L.
So if we didn't put that space it would actually replace the L in leg. So the same thing with the R. I'll replace this with an R and a space. So now all we should need to do is go to tool and mirror and you'll see that we now have mirrored our legs, and all we have to do is just move our spline wrap over just a little bit there, and that should fix our leg issue, and now to animate this character, all we need to do is animate the leg pole and goals to get this guy moving and grooving.
Now, one thing you can do is actually remove the leg goals from the entire group. So you can see that I have my whole blueberry group here and if I move my leg goals out from underneath that group I can actually move everything and those feet can stay planted because the goals are not moving with the rest of the object. So this guy's getting down in our view port here and again, now all you have to do is just key frame all of these little elements, the legs, goals, poles, and the actual body, and we can get an animated character.
So using point IK with spline wraps is a really easy way to rig up a character in the popular rubber hose style. Be sure to check out my website, eyedesyn.com, to see how you can quickly animate a walk cycle using this rubber hose technique. Don't want to wait until next week to learn something new? No problem. Here are other ways to feed your creative brain to keep you busy in the mean time. You can check out my other courses in the library, visit my website eyedesyn.com for more tutorials, subscribe to my YouTube channel to be alerted when I post a new video, join my Facebook page for daily mo graph inspiration, and keep up to date on all my latest mo graph creations on Instagram.
Thanks for watching, and I'll see you here again next week.
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