constraint

Creates a constraint between a target and a constrained node.

This modifier supports common constraint types such as orient, aim, point, parent, and scale. It handles multiple targets and offers fine control over offsets, blending, and skipped channels.

Usage

A constraint modifier defines a specific constraint setup that can be applied to a single node or broadcasted across multiple nodes.

1. Target Setup (Single or Batch): Determine the type of constraint you need. You can apply it to a single DAG node (using node), or provide a list of nodes (using nodes). If a list is provided, the exact same constraint setup (same targets, weights, and offsets) is reproduced identically on every node in the list.
2. Channel Validation & Blending: Before applying the constraint, the framework automatically evaluates the state of the target node's channels based on the constraint type:
   • Free Channels: If the channels are clear, the connection is made directly.
   • Connected Channels: If connections already exist, the modifier automatically creates a blend between the new constraint and the old connections. It adds a blend_*** attribute (e.g., blend_translate, blend_orient) to the constrained node.
   • Forced Blending: You can force the creation of a blend attribute even if no prior connections exist by setting blend: on. This is very useful for creating manual switches on the constrained node.

Limitation

The modifier will abort and refuse to apply the command if a blend setup already exists on the targeted channels.

Coming Soon

A dedicated tool is on the roadmap! It will automatically convert constraints applied manually in your viewport into YAML modifier notes.

Parameters

Core Parameters

Parameter	Type	Default	Description
type	str		Type of constraint. Must be one of: orient, aim, point, parent, scale.
node	node		Node being constrained.
nodes	list[node]		List of nodes being constrained (if applying the exact same setup to multiple objects).
target	node		Main constraint driver.
targets	list[node]		Additional constraint drivers. If both target and targets are provided, they are combined.

Behavior & Offsets

Parameter	Type	Default	Description
weights	list[float]	1.0	Weights per target.
maintain_offset	bool	off	Maintains the current offset between the target and the node.
blend	bool	off	Forces the addition of blend_translate / blend_orient attributes to the constrained node (if they don't already exist).
skip	str		Channels to skip during connection. Use axes like x, y, z, or xy.
skip_translate	str		Same as skip, but strictly applies to translate channels (useful for parent constraints).
skip_rotate	str		Same as skip, but strictly applies to rotate channels.

Aim Specific Parameters (type: aim)

Parameter	Type	Default	Description
aim	str | vector	x	Main aim axis of the constrained node.
up	str | vector	y	Local up axis of the constrained node.
up_vector	str | vector	null	World or object space up vector for the constraint. If up_object is set, this behaves as the object rotation up vector. If not, it is treated as a world space vector (vector mode).
up_object	node		Reference object for the up vector. If up_vector is not set, this node is used as the target up object (object up mode). If up_vector is set, it's used in object rotation up mode.
flip	bool	off	Inverts the aim and up axes if the mod is executed in a mirrored branch.

Vector formatting

Whenever a parameter expects a vector, you can provide it as:

• Named axes: x, y, z, -x, -y, -z
• 3D array format: [0, 1, 0]

Output

The generated constraint node follows this naming convention: <id>::mod.constraint.<type>.<index>

Its target weights will be automatically exposed on plugs: @w0, @w1, @w2, etc.

Examples

Demo Scene

You can explore a practical example of aim constraints. Download the mod_lookat_rig.ma demo scene from our Google Drive folder.

Basic Aim Constraint

Creates an aim constraint maintaining offset, aiming down the Y axis with X as the up vector.

constraint:
  type: aim
  node: <tpl>::infs.0
  target: <target>::node
  maintain_offset: on
  aim: y
  up: x

Multi-Node Point Constraint

Applies the exact same point constraint to a list of multiple nodes simultaneously.

constraint:
  type: point
  nodes:
    - <tpl-a>::infs.0
    - <tpl-b>::infs.0
    - <tpl-c>::infs.0
  target: <target>::main_ctrl