Making simple collision objects

When using Maya make sure to keep in mind that the main menu bar and other areas of the interface might change based on which "mode" you're in. You can find most of these options in the tab shelf of the standard layout but you can also select "Dynamics" from the dropdown and change the main menu accordingly.

Setting up a scene

Let's run through the process of adding simple collision objects within Autodesk Maya.

  1. Select the object (or multiple objects) which will be moved by the physics solver.
  2. Within the "Dynamics" tab click the "Active Rigid Body" icon.
  3. Select the object (or multiple objects) which will not move but which will interact with active rigid bodies.
  4. Click the "Passive Rigid Body" icon.
  5. Select all the objects you want to be affected by gravity.
  6. While still within the Dynamics tab, click the Gravity button (make sure it's the gravity that has "create a gravity field" for the tool tip).

Setting up a basic scene is as simple as that. You'll find that Maya does have some quirks heh "some" that appear however when you try to either add new objects to an existing system or add new objects to an existing field.

Adding new objects

If you make a new object an Active Rigid Body but it does not interact with other objects in the scene. Select one object that IS within your physics system and then select the new object (you don't have to hold shift). Maya chooses which solver system it is working in based on the solver system of the last object you had selected.

If you wish to add another object to a gravity field then don't just click the "gravity field" button again with the object selected. This will make a second gravity field. It won't change the actual way the scene works very much but it might make it harder to work with because then if you want to change an aspect of the field you'll have to do so for each gravity field object.

Instead click the existing gravity field (it's easiest to do this from the outliner), shift-click the new object, and then select "add to field" either from the menu or from the dynamics shelf button.

Collision Meshes

To make the collision mesh invisible.

Go to the object attributes and look for the basic poly object attribute. Typically this is the first one in the attribute tab list.

Within this tab, within the "Display" section, check "template" to have the object display only in a wireframe mode that allows you to see your visible mesh. While in this mode the collision mesh will not render either.

To use the constraint method to keep the visible mesh position matching the collision mesh position.

  1. Select the collision mesh.
  2. Select the visible mesh.
  3. While in the animation menu mode go "Constrain > Parent" to constrain the visible mesh to the position of the collision mesh.

Cloth

Cloth objects in Maya are fairly easy to set up. You may want to make sure you're using the default layout. Most all cloth actions are found within the "nCloth" tab of the tools shelf as seen below.

Basic Cloth Setup

To set up a simple cloth / collider scene...

  1. Select the object that is to act like cloth.
  2. Select "Given a selected mesh, create nCloth". This is typically the first icon (Red Arrow).
  3. Select any objects you wish the cloth to interact with.
  4. From the same shelf tab select "Make the selected meshes collide with nCloth". (Green Arrow)
  5. For cloth, unlike rigid and soft body dynamics, you do not have to apply a gravity field for the cloth to fall.

You may think that you need a gravity field as with active and passive rigid body setups but you actually don't. The cloth object has a default gravity applied upon creation.

On top of that boned meshes will interact with cloth just fine so you don't have to apply any special settings for them to work.

Cloth Constraints

If we don't want loose cloth, and want to create constraints for attaching part of it to specific points, then we can apply transform contstraints.

  1. Select the cloth object.
  2. Go into the normal vertex component mode and select the vertices you do NOT want to move.
  3. From the "nCloth" tab of the default shelf select the "Create a transform constraint for selected nucleus object points". (Blue Arrow)

Once done the selected vertices will be permanently highlighted in dark blue even when the object is not selected to let you know which ones are not part of the physics animation. Ideally you'd probably make this points align with a parent object that can move the cloth object around. For instance a simple cloth square can be made the child of a thin cylinder to make a flag pole and the points where the cloth touches the pole can be constrained to keep the cloth from floating away from the pole.

Alternately we can bind them to a surface via point constraints rather than as a child.

Cloth constraints (point constraints)

If you have a surface that either deforms or a setup that is not suitable for a cloth object as a child it may be easier to just use the point constraint options. It's fairly simple.

  1. Select the cloth object.
  2. Go to the vertex sub-object mode and select the verices you wish to constrain to an object surface.
  3. Shift-click to select the object to constrain the points to.
  4. Click the "Select dynamic objects..." button from the nCloth toolbar (the red arrow).

The points should now stay attached to that object. If the object should move it will take the cloth object with it, even without a parent / child relationship.