movis.attribute#

The Attribute class is used for animating properties of either Layer or Effect. The value of a property at a given time can be obtained using the attribute(time). The dimensionality of the returned np.ndarray varies depending on the value_type specified at initialization.

>>> from movis.attribute import Attribute, AttributeType
>>> attr1 = Attribute(1.0, AttributeType.SCALAR)
>>> attr1(0.0)
array([1.])
>>> attr2 = Attribute([0.0, 1.0], AttributeType.VECTOR2D)
>>> attr2(0.0)
array([0., 1.])

Note

Even if a scalar is specified, the ndim of the returned np.ndarray will be 1.

`movis.attribute.Attribute`	Attribute class for animating the specified property.
`movis.attribute.AttributesMixin`	A mix-in class with a collection of methods for implementing layers or effects using attributes.
`movis.attribute.AttributeType`	A type used to determine the type and dimension of an attribute.

Initialization#

At the time of initialization, no animation is applied to the Attribute. In other words, the value returned by attr(time) is constant, irrespective of the time.

To replace such a constant value, you can either use attr.init_value = new_value or call attr.set(new_value). In either case, the type of new_value will be appropriately converted and used as the initial value.

There are two ways to apply animation:

Use the enable_motion() method to attach a Motion instance.
Use the add_function() method to attach a user-defined function.

The more convenient way for users is to use the enable_motion(). You only need to specify the keyframes and their associated values, along with the easing method.

enable_motion()#

The implementation of enable_motion() creates an instance of the Motion class, sets it as the animation, and returns that instance.

>>> from movis.attribute import Attribute, AttributeType
>>> attr = Attribute(0.0, AttributeType.SCALAR)
>>> attr.enable_motion().extend(
...     keyframes=[0.0, 1.0], values=[0.0, 1.0], easing=["linear"])
>>> attr(0.0)
array([0.])
>>> attr(0.5)
array([0.5])

Note

If a Motion instance already exists, enable_motion() will return the existing instance without creating a new one.

For details on the Motion class, refer to the corresponding API documentation. Typically, you add keyframes using the append() or extend() methods.

add_function()#

The add_function() method allows you to define more complex animations using a user-defined function. In this case, the provided function must take both the value before function application and the time as arguments, and return a new value. This can be useful for adding some variability to existing animations, such as a wiggle effect.

>>> from movis.attribute import Attribute, AttributeType
>>> import numpy as np
>>> attr = Attribute(0.0, AttributeType.SCALAR)
>>> attr.add_function(lambda x, t: x + 0.1 * np.sin(t))
>>> attr(0.0)
array([0.])
>>> attr(0.5)
array([0.04794255])