# Constraint COMP

## Summary

A Constraint COMP is used to restrict the movement of bodies within an Actor COMP. Currently this can be done in a few ways: point to point, hinge or slider. Constraints can either be applied on a single body or between two bodies. Constraints can be used to create connectivity between bodies, or to create bodies that can move but need to have that movement restricted in some way. Some examples of constraints in the real world: a train, a door, an arm.

If a point to point constraint is applied to a single body, then that body will be restricted to 3 degrees of freedom (DOF). It will still have all 3 degrees of freedom for rotation (ie. All 3 axes), but the 3 degrees of freedom for translation will all be constrained. If a point to point constraint is applied between two bodies, then they will both be similarly constrained to 3 DOF. However, they will be able to move (translate) along all 3 axes but they will do it connected to each other at their pivot points. By using this constraint method, a chain of bodies can be created. For instance, point to point constraints can be used to simulate train cars connected to each other.

If a hinge constraint is applied to a single body, then that body will be restricted to 1 DOF. It will only be able to rotate around 1 axis, and that axis is defined using the Axis parameter on the Constraint COMP. Much like the point to point constraint, the hinge also as a pivot point around which it will rotate. If a hinge constraint is applied between two bodies, then they will both be able to move with 3 DOF but they will do it connected to each other at their pivot points. However, they will still only be able to rotate around their respective axis. The simplest example of a hinge constraint is a door.

If a slider constraint is applied to a single body, then that body's translation/rotation will be constrained to just that axis. In other words, the body can only move along that axis (either direction) and can only rotate along that axis (either direction).

## Parameters - Constraint Page

Active active - Toggle the constraint on/off in the simulation.

Type type - - The type of constraint to create: point to point, hinge, or slider.

• Point To Point p2p -
• Hinge hinge -
• Slider slider -

Body to Body bodytobody - Toggle body to body mode on/off. Body to body mode creates a constraint between two bodies (Actor 1 Bodies and Actor 2 Bodies). When toggled off it will create constrain bodies individually. If Actor 1 Bodies and Actor 2 Bodies contain the same number of referenced bodies, then this mode will create a constraint between each respective pair. For instance, if Actor 1 Bodies contains the string "0 1 2", and Actor 2 Bodies contains the string "3 4 5" then this will create 3 constraints: 0->3, 1->4, 2->5. It is a 1 to 1 relationship between these two parameters. However, if Actor 1 Bodies has more bodies than Actor 2 Bodies, then the remaining "unmatched" bodies of Actor 1 Bodies will instead be individually constrained. For instance, if Actor 1 Bodies contains the string "0 1 2" and Actor 2 Bodies contains the string "3 4", then two constraints will be created between bodies: 0->3, 1->4. Body 2 will be constrained individually. If Actor 2 Bodies contains more bodies than Actor 1 Bodies, then any unmatched bodies in Actor 2 Bodies will simply be disregarded (no constraint created for them).

Collisions between Bodies collisions - Turns on/off collisions between the body to body constraints.

Display Constraint dispcom - Turns on/off the display of the constraint guide in the viewer.

Actor COMP actor1 - A reference to an Actor COMP. This specifies the Actor COMP of which you want to constrain some bodies.

Actor Bodies bodies1 - A list (regular expression) of the IDs of the bodies in actor1 to constrain. If an Actor COMP contains N bodies, then body IDs will go from 0 to N-1 for that Actor COMP. The number of bodies can be verified using the Bullet Solver CHOP.

Pivot pivot1 - - The pivot point for the constraint.

• X pivot1x -
• Y pivot1y -
• Z pivot1z -

Hinge Axis axis1 - - The axis around which to create the hinge. Each value is typically a number between 0 and 1. For example, to spin around the Z axis set to 0, 0, 1.

• X axis1x -
• Y axis1y -
• Z axis1z -

Slider Rotation sliderrot1 - - The rotation of the slider constraint axis. By default the slider constraint is applied on the X axis.

• X sliderrot1x -
• Y sliderrot1y -
• Z sliderrot1z -

Actor COMP actor2 - A reference to an Actor COMP. This specifies the Actor COMP of which you want to constrain some bodies. This Actor COMP is only used when body to body mode is toggled on.

Actor Bodies bodies2 - A list (regular expression) of the IDs of the bodies in actor2 to constrain. If an Actor COMP contains N bodies, then body IDs will go from 0 to N-1 for that Actor COMP. The number of bodies can be verified using the Bullet Solver CHOP.

Pivot pivot2 - - The pivot point for the constraint.

• X pivot2x -
• Y pivot2y -
• Z pivot2z -

Hinge Axis axis2 - - The axis around which to create the hinge. Each value is typically a number between 0 and 1. For example, to spin around the Z axis set to 0, 0, 1.

• X axis2x -
• Y axis2y -
• Z axis2z -

Slider Rotation sliderrot2 - - The rotation of the slider constraint axis. By default the slider constraint is applied on the X axis.

• X sliderrot2x -
• Y sliderrot2y -
• Z sliderrot2z -

## Parameters - Limits Page

Enable Limits enablelimits - Enables limits on the constraint. Without constraints, the bodies will be able to rotate a full 360 degrees, or translate any distance.

Lower Linear Limit lowerlinlim - The lower limit for translation of the body along the constraint. Only used with slider constraints.

Upper Linear Limit upperlinlim - The upper limit for translation of the body along the constraint. Only used with slider constraints.

Lower Angular Limit loweranglim - The lower limit for rotation of the body around its axis. Used with slider constraints or hinge constraints.

Upper Angular Limit upperanglim - The upper limit for rotation of the body around its axis. Used with slider constraints or hinge constraints.

## Parameters - Extensions Page

Extension Object 1 extension1 - A number of class instances that can be attached to the component.

Extension Name 1 extname1 - Optional name to search by, instead of the instance class name.

Promote Extension 1 promoteextension1 - Controls whether or not the extensions are visible directly at the component level, or must be accessed through the .ext member. Example: n.Somefunction vs n.ext.Somefunction

Extension Object 2 extension2 - A number of class instances that can be attached to the component.

Extension Name 2 extname2 - Optional name to search by, instead of the instance class name.

Promote Extension 2 promoteextension2 - Controls whether or not the extensions are visible directly at the component level, or must be accessed through the .ext member. Example: n.Somefunction vs n.ext.Somefunction

Extension Object 3 extension3 - A number of class instances that can be attached to the component.

Extension Name 3 extname3 - Optional name to search by, instead of the instance class name.

Promote Extension 3 promoteextension3 - Controls whether or not the extensions are visible directly at the component level, or must be accessed through the .ext member. Example: n.Somefunction vs n.ext.Somefunction

Extension Object 4 extension4 - A number of class instances that can be attached to the component.

Extension Name 4 extname4 - Optional name to search by, instead of the instance class name.

Promote Extension 4 promoteextension4 - Controls whether or not the extensions are visible directly at the component level, or must be accessed through the .ext member. Example: n.Somefunction vs n.ext.Somefunction

Re-Init Extensions reinitextensions - Recompile all extension objects. Normally extension objects are compiled only when they are referenced and their definitions have changed.

## Parameters - Common Page

The Common parameter page sets the component's node viewer, clone relationships, Parent Shortcut, and Global OP Shortcut.

Parent Shortcut parentshortcut - Specifies a name you can use anywhere inside the component as the path to that component. See Parent Shortcut.

Global OP Shortcut opshortcut - Specifies a name you can use anywhere at all as the path to that component. See Global OP Shortcut.

Internal OP Shortcut iopshortcut - Specifies a name you can use anywhere inside the component as a path to "Internal OP" below. See Internal Operators.

Internal OP iop - The path to the Internal OP inside this component. See Internal Operators.

Node View nodeview - - Determines what is displayed in the node viewer, also known as the Node Viewer. Some options will not be available depending on the Component type (Object Component, Panel Component, Misc.)

• Default Viewer default - Displays the default viewer for the component type, a 3D Viewer for Object COMPS and a Control Panel Viewer for Panel COMPs.
• Operator Viewer opviewer - Displays the node viewer from any operator specified in the Operator Viewer parameter below.

Operator Viewer opviewer - Select which operator's node viewer to use when the Node View parameter above is set to Operator Viewer.

Keep in Memory keepmemory -

Enable Cloning enablecloning - Control if the OP should be actively cloned. The Pulse button can be used to instantaneously clone the contents.

Enable Cloning Pulse enablecloningpulse -

Clone Master clone - Path to a component used as the Master Clone.

Load on Demand loadondemand - Loads the component into memory only when required. Good to use for components that are not always used in the project.

External .tox externaltox - Path to a .tox file on disk which will source the component's contents upon start of a .toe. This allows for components to contain networks that can be updated independently. If the .tox file can not be found, whatever the .toe file was saved with will be loaded.

Reload .tox on Start reloadtoxonstart - When on (default), the external .tox file will be loaded when the .toe starts and the contents of the COMP will match that of the external .tox. This can be turned off to avoid loading from the referenced external .tox on startup if desired (the contents of the COMP are instead loaded from the .toe file). Useful if you wish to have a COMP reference an external .tox but not always load from it unless you specifically push the Re-Init Network parameter button.

Reload Custom Parameters reloadcustom - When this checkbox is enabled, the values of the component's Custom Parameters are reloaded when the .tox is reloaded.

Reload Built-In Parameters reloadbuiltin - When this checkbox is enabled, the values of the component's built-in parameters are reloaded when the .tox is reloaded.

Save Backup of External savebackup - When this checkbox is enabled, a backup copy of the component specified by the External .tox parameter is saved in the .toe file. This backup copy will be used if the External .tox can not be found. This may happen if the .tox was renamed, deleted, or the .toe file is running on another computer that is missing component media.

Sub-Component to Load subcompname - When loading from an External .tox file, this option allows you to reach into the .tox and pull out a COMP and make that the top-level COMP, ignoring everything else in the file (except for the contents of that COMP). For example if a .tox file named project1.tox contains project1/geo1, putting geo1 as the Sub-Component to Load, will result in geo1 being loaded in place of the current COMP. If this parameter is blank, it just loads the .tox file normally using the top level COMP in the file.

Re-Init Network reinitnet - This button will re-load from the external .tox file (if present), followed by re-initializing itself from its master, if it's a clone. If pulsed in a Python script, any old OP references to this node will be invalid and should be reacquired.   TouchDesigner Build:

Experimental:Actor • Actor • Ambient Light • Animation • Base • Blend • Bone • Bullet Solver • Button • Experimental:Button • Camera Blend • Camera • Component • Constraint • Container • Experimental:Container • Experimental:Engine • Environment Light • FBX • Field • Experimental:Field • Force • Experimental:Force • Geometry • Experimental:Geometry • Handle • Impulse Force • Light • List • Experimental:List • Null • Nvidia Flex Solver • Nvidia Flow Emitter • Experimental:Nvidia Flow Emitter • OP Viewer • Parameter • Replicator • Select • Shared Mem In • Shared Mem Out • Slider • Table • Time • USD • Widget • Window

An Operator Family that contains its own Network inside. There are twelve 3D Object Component and eight 2D Panel Component types. See also Network Path.

Each SOP has a list of Points. Each point has an XYZ 3D position value plus other optional attributes. Each polygon Primitive is defined by a vertex list, which is list of point numbers.

An Operator Family which operate on Channels (a series of numbers) which are used for animation, audio, mathematics, simulation, logic, UI construction, and many other applications.

Any component can be extended with its own Python classes which contain python functions and data.

The component types that are used to render 3D scenes: Geometry Component contain the 3D shapes to render, plus Camera, Light, Ambient Light, Null, Bone, Handle and other component types.

A Parent Shortcut is a parameter on a component that contains a name that you can use anywhere inside the component to refer to that component using the syntax parent.Name, for example parent.Effect.width to obtain panel width.

A name for a component that is accessible from any node in a project, which can be declared in a component's Global Operator Shortcut parameter.

There are four types of shortcuts: Application Shortcuts that are built-in to TouchDesigner's authoring interface, Panel Shortcuts that you create for any custom built panels, Parent Shortcuts for accessing a component from within that component, and Global OP Shortcuts that access a unique component from anywhere in TouchDesigner.

Any of the procedural data operators. OPs do all the work in TouchDesigner. They "cook" and output data to other OPs, which ultimately result in new images, data and audio being generated. See Node.

An Operator Family that contains its own Network inside. There are twelve 3D Object Component and eight 2D Panel Component types. See also Network Path.

The viewer of a node can be (1) the interior of a node (the Node Viewer), (2) a floating window (RMB->View... on node), or (3) a Pane that graphically shows the results of an operator.

A custom interactive control panel built within TouchDesigner. Panels are created using Panel Components whose look is created entirely with TOPs.

To pulse a parameter is to send it a signal from a CHOP or python or a mouse click that causes a new action to occur immediately. A pulse via python is via the .pulse() function on a pulse-type parameter, such as Reset in a Speed CHOP. A pulse from a CHOP is typically a 0 to 1 to 0 signal in a channel.

Cloning can make multiple components match the contents of a master component. A Component whose Clone parameter is set will be forced to contain the same nodes, wiring and parameters as its master component. Cloning does not create new components as does the Replicator COMP.

The location of an operator within the TouchDesigner environment, for example, /geo1/torus1, a node called torus1 in a component called geo1. The path / is called Root. To refer instead to a filesystem folder, directory, disk file or http: address, see Folder.

TouchDesigner Component file, the file type used to save a Component from TouchDesigner.

TOuch Environment file, the file type used by TouchDesigner to save your project.

Every component contains a network of operators that create and modify data. The operators are connected by wires that define where data is routed after the operator cooks its inputs and generates an output.