Pinning Vertices

In this guide, you will learn how to pin vertices to their world position or to another object.

Building the Scene

To get started, we will only need a very simple scene consisting of a square plane with

  • Length = 100 cm
  • Width = 100 cm
  • Length Segs = 40
  • Width Segs = 40

Then, go ahead and add a Dynamo modifier to the plane and your scene should look like the image below

Initial scene
The scene before simulation

Pinning to World Space

Pin panel

Now, enter pinning mode by pressing Pins in the Sub objects rollup. Select two vertices at the corners of the plane and press Set. The pinned vertices should now be highlighted in yellow, as shown in the image below.

Pinned verts
The plane with its corners pinned

By default Dynamo has a ground collider activated. For this example we will need to disable it. Go to the DynamoSolver object or scroll down to the solver section in the DynamoModifier (they mirror each other) and uncheck Ground collider.

Pinned verts
The ground collider is disabled on the DynamoSolver object.

Press Bake in the simulation rollup to run the simulation. The plane should fall but the two corners you pinned should stay in place.

Sim panel

Animation with pins, frame 10 Animation with pins, frame 100
The simulation at frame 10 The simulation at frame 100

Pinning to an Object

Another alternative is to pin the vertices to the surface of an object. Let's look at how that is done.

First, create a box with

  • Length = 100 cm
  • Width = 400 cm
  • Height = 50 cm
  • Width Segs = 40

and place it so that it touches the edge of the plane, as shown in the image below.

Initial scene
The scene with a box

Also, add a bend modifier to the box, set the axis to X and add a keyframe of -300 for the Angle at frame 100. The box will curl up and now we want to pin the plane to the box so that it sticks to it during the simulation.

Select the plane and go into Pins mode. Enable Pin to object in the Sub Objects rollup and select the box as the pinning object by pressing the button labeled None and then clicking the box.

Pin panel

Press Bake and the two vertices should now be pinned to the surface of the box, as seen below.

Animation with pins to box, frame 40 Animation with pins to box, frame 100
The simulation at frame 40 The simulation at frame 100

Pinning Strength

In the pinning settings, there is a Strength setting that determines how strong the bond to the surface is. In some contexts it is usefull to have a strength value lower than 1. Pins are often used to make keep clothes from falling off a moving character and in these cases a low pinning strength can be a good compromise between having a realistic simulation and keeping the clothes in place.

Conclusion

You have seen how to pin vertices either in world space or to the surface of an object. The latter is useful when simulating clothes, for instance to make sure that a pair of trousers do not slip off the body of an avatar.