Constraint Solver
Bottom of the Page

Create panel (Helpers) reactor CSolver

Animation menu reactor Create Object Constraint Solver

reactor toolbar (Create Constraint Solver)

The Constraint Solver acts as a container for the cooperative constraints in a particular Rigid Body Collection, and performs all the calculations necessary for the constraints to work together.

For a cooperative constraint to be simulated in a scene, it must be included in a valid Constraint Solver and any of the rigid bodies it contains should be in the Rigid Body Collection associated with the solver. For a Constraint Solver to be valid it should be associated with a valid Rigid Body Collection. When not selected, an invalid Constraint Solver is red in the viewport.

You can disable an entire Constraint Solver, thus disabling all of its constraints. You can also set a deactivation threshold for all the constraints in the solver, which lets you specify when you would like all the relevant rigid bodies to be deactivated.


To create a Constraint Solver:

To assign a Rigid Body Collection to the solver:

  1. On the Properties rollout click the RB Collection button.

    This enters a pick mode in which you can choose only a Rigid Body Collection.

  2. In one of the viewports, click the collection to assign to the Constraint Solver. The collection should contain the rigid bodies for the constraints in the solver.

To add constraints to a solver:

  1. Create a Constraint Solver and some cooperative constraints to add to the solver.
  2. Add constraints to the solver using either (or both) of these methods:
    • On the Constraint Solver Properties rollout, click the Pick button, and then in the viewport click a constraint helper to add.
    • On the Properties rollout, click the Add button, and then use the dialog to specify one or more constraints to add.


Properties rollout

RB Collection button

Displays the name of the Rigid Body Collection assigned to the solver, if any. To assign a Rigid Body Collection to the solver, click this button and then selecting a collection in any viewport.


Click this button to cause the constraints in the Constraints list to momentarily display in the viewports as if selected.


Lists the names of the constraints currently in the solver.


Lets you add a constraint to the solver. Click this button, then in the viewport move the cursor over the constraint you would like to add to the solver. If the object can be used as a constraint, the cursor changes from an arrow to a cross and you can select the object to add it to the solver.


Lets you add one or more constraints from the scene to the solver. Click the button to open up the Select New Constraints To Add dialog. Make a selection in the provided list, and then add the constraints to the solver by pressing the Select button.


Lets you remove constraints from the solver. Highlight the constraints to remove from the solver in the Constraints list and then click this button.

Deactivation Threshold

Lets you specify a special deactivation threshold for all the rigid bodies constrained by the solver's constraints. Objects in a Constraint Solver are activated and deactivated together; this parameter specifies how aggressive the deactivation is. A value of 0.0 disables deactivation. For more information about deactivation, see Havok 1 World / Havok 3 World Rollout.


When on, disables all the constraints in this solver.

Reset Default Values

Sets Deactivation Threshold and Disabled to their respective default values.