(constraint)=
# Constraint
As its name suggests, **Constraints** are used to limit the value of a property or influence it with another one. It is often used to create sophisticated animation.

## Adding a Constraint
Adding a constraint is very similar to [adding a modifier](modifier:add). Select an object, and switch to `Constraints` tab in the properties area. <kbd>Left Mouse Click</kbd> on `Add Object Constraint` brings up the dropdown menu and you can choose the constraint you want to add. The order of constraints matters and they are applied from top to bottom, just like modifiers.
```{figure} ../../assets/modeling/constr_add.png

```

## Basic Constraints

::::{tab-set}
:::{tab-item} Copy...
**Copy Location/Rotation/Scale/Transforms** links an object's movement/deformation to a target object. Set the `Target` by typing its name, choosing it in the dropdown menu, or using the eyedropper tool. You can also change on which axes the constraint takes effect using `Axis X/Y/Z`, and the options are not mutually exclusive.


```{figure} ../../assets/modeling/constr_copy.gif
:width: 100%
```

:::

:::{tab-item} Limit...
**Limit Location/Rotation/Scale/Distance** put restrictions on an object's movement/deformation. `Limit Location/Rotation/Scale` are quite self-explanatory, and `Limit Distance` limits the object's distance to the target like a leash.
```{figure} ../../assets/modeling/constr_copy_w_limit.gif
:width: 100%
```

:::

:::{tab-item} Track To
The **Track To** constraint makes an object always facing the target by rotating it. Adjust `Track Axis` and `Up` for the desired effect. If you find the object rotates too fast at certain positions, try the `Damped Track` constraint instead.
```{figure} ../../assets/modeling/track_to.gif
:width: 100%
```

:::

:::{tab-item} Follow Path
The **Follow Path** constraint makes an object move along a curve. Adjust `Forward Axis` and `Up Axis` to align the object, and turn on `Curve Radius` and `Follow Curve` if you want the curve's normal, tilt, and radius to affect the object. `Animate Path` gives the target curve a basic animation if it doesn't have one already.
```{figure} ../../assets/modeling/follow_path.gif
:width: 100%
```

:::

::::