# Transitions

Transitions can be used as part of the with statement, as well as in other parts of Ren'Py, to apply effects to changes in the scene (or sometimes to turn a displayable into another). Ren'Py comes with a small number of pre-defined transitions, which can be given directly to the with statement. For example:

    show bg washington
    with dissolve

## Pre-Defined Transitions

dissolve

  Takes 0.5 seconds to dissolve from the old to the new screen. An instance of the `Dissolve()` transition class.

fade

  Takes 0.5 seconds to fade to black, and then 0.5 seconds to fade to the new screen. An instance of the `Fade()` transition class.

pixellate

  Pixellates the old scene for .5 seconds, and the new scene for another .5 seconds. An instance of the `Pixellate()` transition class.

move

  Takes 0.5 seconds to the move images that have changed location to their new locations. An instance of the `MoveTransition()` transition class.

  Move transitions, and similar transitions like ease, can only be applied to a single layer or all layers at once, using the with statement. It will not work in other contexts such as ATL, `ComposeTransition()`, or other ways of applying transitions.

moveinright

  Also: moveinleft, moveintop, moveinbottom

  These move entering images onto the screen from the appropriate side, taking 0.5 seconds to do so.

moveoutright

  Also: moveoutleft, moveouttop, moveoutbottom

  These move leaving images off the screen via the appropriate side, taking 0.5 seconds to do so.

ease

  Also: easeinright, easeinleft, easeintop, easeinbottom, easeoutright, easeoutleft, easeouttop, easeoutbottom

  These are similar to the move- family of transitions, except that they use a cosine-based curve to slow down the start and end of the transition.

zoomin

  This zooms in entering images, taking 0.5 seconds to do so.

zoomout

  This zooms out leaving images, taking 0.5 seconds to do so.

zoominout

  This zooms in entering images and zooms out leaving images, taking 0.5 seconds to do so.

vpunch

  When invoked, this transition shakes the screen vertically for a quarter second. Imitating and customizing this transition and `hpunch` is best done using ATL Transitions.

hpunch

  When invoked, this transition shakes the screen horizontally for a quarter second.

blinds

  Transitions the screen in a vertical blinds effect lasting 1 second. An instance of the `ImageDissolve()` transition class.

squares

  Transitions the screen in a squares effect lasting 1 second.

wipeleft

  Also: wiperight, wipeup, wipedown

  Wipes the scene in the given direction. Instances of the `CropMove()` transition class.

slideleft

  Also: slideright, slideup, slidedown

  Slides the new scene in the given direction. Instances of the `CropMove()` transition class.

slideawayleft

  Also: slideawayright, slideawayup, slideawaydown

  Slides the old scene in the given direction. Instances of the `CropMove()` transition class.

pushright

  Also: pushleft, pushup, pushdown

  These use the new scene to slide the old scene out the named side. Instances of the `PushMove()` transition class.

irisin

  Also: irisout

  Use a rectangular iris to display the new screen, or hide the old screen. Instances of the `CropMove()` transition class.

## Transition Classes

Transition classes are functions that can be called to create new transitions. These functions are parameterized, allowing entire families of transitions to be created. Unlike what the term may imply, they are usually not classes in the Python sense and should not be treated as such.

Calling transition classes can be done as part of the with statement. For example:

    # A very long dissolve.
    with Dissolve(10.0)

If the same transition class is used repeatedly, the define statement can be used to assign the transition to a variable:

    define dissolve1 = Dissolve(1.0)

    label start:
        show bg washington
        with dissolve1

The time_warp argument taken by many transition classes can be given built-in warpers found in the `_warper` module, see warpers.

## Transition Families

Transition families are functions that define a large family of related transitions.

## Dict Transitions

In many places where Ren'Py takes a transition, it's possible to instead specify a dictionary that maps layer names to this transition. When this is the case, Ren'Py applies each transition to the appropriate layer.

When a dict is used, the pause that usually occurs when a transition takes place does not occur. Instead, the statement taking the dictionary returns immediately, and the transitions are scheduled to occur at the start of the next interaction.

This can be used with the master layer to cause transitions to occur while dialogue is being shown on the screen. For example:

    define dis = { "master" : Dissolve(1.0) }

    label start:
        show eileen happy
        with dis

        e "Hello, world."

The dissolve will take place while the text is displayed on the screen.

Dict layer transitions can't be used every place a transition can be used, only in places where applying transitions to a layer is possible. It can be used with the With Statement and `with` cause of the scene, show, and hide statements. It can also be used with `renpy.with_statement()` and `renpy.transition()`, the `Show()` and `Hide()` actions, and various config variables that take transitions. Dict layer transitions will not work inside things that don't work with layers, such as ATL - Animation and Transformation Language, `ComposeTransition()` and `MultipleTransition()`.

This can interact poorly with statements that cause a transition to occur themselves, like the transitions caused by `window auto`. That can often be solved with a second dict transition that applies to a different layer. For example, if you are seeing weird blinking when the dialogue window shows and hides, consider changing `options.rpy` to have:

    define config.window_show_transition = { "screens" : Dissolve(.25) }
    define config.window_hide_transition = { "screens" : Dissolve(.25) }

This works because the dialogue window exists entirely on the screens layer.

## ATL Transitions

See also: ATL - Animation and Transformation Language

It's possible to use an ATL transform to define a transition. These transitions need to accept the old_widget and new_widget arguments, which will receive displayables representing the screens that are transitioned from and to, respectively.

An ATL transition must set itself the `delay` property to the number of seconds the transition lasts for. It may use the `events` property to prevent the old displayable from receiving events.

    transform spin(duration=1.0, *, new_widget=None, old_widget=None):

        # Set how long this transform will take to complete.
        delay duration

        # Center it.
        xcenter .5
        ycenter .5

        # Spin the old displayable.
        old_widget
        events False
        rotate 0.
        easeout (duration / 2) rotate 360.0

        # Spin the new displayable.
        new_widget
        events True
        easein (duration / 2) rotate 720.0

## Python Transitions

A Python callable may be used as a transition. For that, it must take two keyword arguments described below, and return a displayable that performs the transition effect - usually by delegating that to another transition. The two keyword arguments are old_widget, which represents the old screen, and new_widget, which represents the new screen.

The displayable returned by the callable should have a `delay` attribute, set to the number of seconds that the transition should run for.

For example:

    init python:
        def dissolve_or_pixellate(old_widget=None, new_widget=None):
            if persistent.want_pixellate:
                return pixellate(old_widget=old_widget, new_widget=new_widget)
            else:
                return dissolve(old_widget=old_widget, new_widget=new_widget)

Accordingly, all kinds of transitions can be called and passed these two keyword arguments, resulting in a displayable animating the transition between the two passed displayables.

## Automatic Transitions after Scene, Show, and Hide

Ren'Py can automatically show a transition after a series of scene, show, and hide statements. This transition can be enabled by setting the `_scene_show_hide_transition` variable to the transition to be used.

The transition will occur after one or more scene, show, and hide statements, provided the statement are not followed by a with statement, or a transition caused by Dialogue Window Management, like the various `window` statements. It's also disabled when in a menu context.

For example:

    define _scene_show_hide_transition = Dissolve(0.25)

    label start:
        scene bg washington
        show eileen happy

        "The transition won't show here, because the dialogue window transitioned in."

        show lucy mad at right

        "The transition will happen here."

        hide lucy mad
        show eileen vhappy

        "And it will happen here, as well."