Tuesday, September 15, 2015

What Is a Pin Constraint in Maya ?

By Laura Gittins

A scene created in Maya consists of several objects, called "bodies," that interact with each other. To do so, you must "constrain" or connect them. A pin constraint is a type of constraint that connects two bodies to each other while still allowing each one to maintain a full range of motion at the end of the pin.

Bodies and Constraints

·         A body is an object that moves. Maya has two types of bodies: soft and rigid. A soft body can change shape while a rigid one does not. Rigid bodies further break down to passive and active rigid bodies, where a passive body can influence an active one, but not vice versa. You use constraints to connect one or more rigid bodies so you can influence how the the body acts and behaves.

Pin Constraint

·         A pin constraint is a specific type of constraint that connects two bodies together, for example a rope hanging from a ceiling, or body parts such as an arm connected to a shoulder. Other bodies in your scene can still interact with these bodies, but the pin constraint will ensure that they do not separate from each other. You cannot constrain one body to a point in space using a pin constraint.


·         To create a pin constraint, click on the two bodies that you want to bind together. The first becomes "Body 1" and the second "Body 2" in the constraint's "relative to" attribute. Click on "Soft/Rigid Bodies," then "Create Pin Constraint." This will add the pin constraint to your scene and open its properties in the options window. Here, you can edit several properties including X, Y and Z values for its position, scale and fulcrum, turn visibility on or off, or even change the type of constraint if needed.

Default Position

·         When you create a pin constraint, the constraint initially connects to the center of the body's mass. For example, if you constrained an arm to a shoulder, the initial connection point would be the center of the arm, which obviously would not look right. Using the move tool, you can click and drag the connection point for the constraint to another section of the body, such as the end of the arm.


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