Join EJ Hassenfratz for an in-depth discussion in this video Adding springs to enable interaction between splines and the screen model, part of Mograph Techniques: Spline Dynamics with CINEMA 4D.
While using constraints connects the splines from the screen to the corner hinges. We still need something to connect the dynamic screen itself to those hinges. In this chapter, I'll show you how this can be done using spring objects. So we have our spline dynamic cables, and we have our screen with dynamics applied. And if we hit Play you can see that our spine dynamics is working fine but we have our screen falling all the way to the floor. So we need something that's going to keep this dynamic relationship and actually hold up this screen.
And springs are going to be the perfect thing for this. So let's create one. Let's go to Dynamics > Spring. And you can see in the spring objects, we can define two objects to create a spring like effect between them. So these objects are going to be one of these hinges in the screen itself. So let's go ahead and start off with the upper right hinge. So let's go ahead and click and drag and bring this upper right hinge into object A. You can see that we have this spring representation, in the view port. And if you render, it actually doesn't show up in the render, it's just visible in the view port to help you out.
So our second object's going to be this screen. Let's actually just click and drag and bring our whole entire screen object in there. You can see that our spring is now connected from the upper right hinge. To the actual center of the screen, and that's because our attachment points are from the center of mass of both of these objects. Or just the center of these objects. So let's go ahead and hit Play and see what we have. So you can see, this isn't the effect that we're trying to get, but you can see that the spring object is creating this springy, bouncing-like effect.
Hanging from this upper right hinge. But because the center of mass is the center of the screen, it's not behaving correctly. We actually need this spring point to be the upper right part of the screen, not the center. So we're going to move that to the corner, by changing the attachment points from each of the hinge and the screen from Center to Offset. So, let's actually go to our front view. Let's just zoom in. So, we can actually offset on the X, Y and Z axises.
The point at which the spring object is created. So, let's move this line. Down to where our spline dynamics constraint is which is right about there. So let's just scrub through here. Try to get this as close as possible. So that's looking pretty good. We're going to do the same thing to the attachment point on our screen object. We're going to change to Offset as well and move that Spring line to connect to this upper right corner of the screen.
So we're going to get it to where this little yellow dot is. Let's adjust the offset values here, the X and the Y. Let's zoom in here. I think we've got that looking Close enough, it's looking good now lets go back to our perspective view lets hit Play. So now it's looking a lot better, we have our screen hanging and dangling off of this hinge.
You can see that our spline or our cable. Has a lot of slack to it. So the effect of this screen hanging from this cable, isn't really getting sold very well. We need this to actually be a pretty taught cable, and this just has way too much slack. So to fix this we're going to go into our Spring options, and you can see we have a rest length. And, it's actually set to 100 right now. So, what the rest length is, is the actual length of the spring when at rest.
So, the default value of 100 isn't working right now. So, we can fix this, and change it to the actual length between these two objects by hitting set rest length. So, you can see that that changes from the default 100 centimeters. To about 119 or 120 centimeters. So let's hit Play and see what that did. So hitting set res length now takes into account the actual distance from each of those points that we define with these offsets. And now we have our cable pretty taut and we're selling the effect of this cable Dangling this screen from this hinge, using the cable.
So let's go ahead and set up the spring on the upper left side. So let's just rename this to Upper Right Spring. Let's create another spring. Rename this upper left spring. So let's go ahead and define our objects. So it's going to be the upper left hinge here and connect that to our screen. And again, we're going to change the attachment points from Center of Mass to Offset, on each of the upper left hinge and the screen.
We're going to go back to our front view, so we get a better view. Let's just change the offset of these, this hinge, closer to where that yellow dot is. It's looking good. And then change it change the offset of our screen. Zoom and make sure that's close to that yellow dot there. That looks good. And we'll zoom out and let's go to our perspective view again.
And again we have to set that rest length because the 100 centimeters value wasn't working. And so by hitting the Set Rest Length, that's now changed to the actual distance between those two points that we set in the offsets and let's hit Play. So, now we have our screen hanging from these cables that are connected to the hinges. And everything's reacting like they would in real life if you actually had a sign dangling from some cables.
So, using springs You can create these dynamic relationships between objects. Along with spline dynamics, you can create the effect of objects hanging by a cable.
- Adding cable splines and spline dynamic tags
- Using constraint tags
- Adding sweeps tags
- Using Spring objects to add tension and interaction
- Creating dynamic camera moves
- Adding depth of field and motion blur in After Effects