Creates a new instance. The base class' implementation just draws the unmodified input texture.
Indicates if the last filter pass is always drawn directly to the back buffer.
Per default, the filter tries to automatically render in a smart way: objects that are currently moving are rendered to the back buffer, objects that are static are rendered into a texture first, which allows the filter to be drawn directly from the render cache in the next frame (in case the object remains static).
However, this fails when filters are added to an object that does not support the render cache, or to a container with such a child (e.g. a Sprite3D object or a masked display object). In such a case, enable this property for maximum performance.
@default false
The anti-aliasing level. This is only used for rendering the target object into a texture, not for the filter passes. 0 - none, 4 - maximum. @default 0
Indicates if the filter is cached (via the cache
method).
Indicates if the filter requires all passes to be processed with the exact same resolution.
Some filters must use the same resolution for input and output; e.g. the blur filter
is very sensitive to changes of pixel / texel sizes. When the filter is used as part
of a filter chain, or if its last pass is drawn directly to the back buffer, such a
filter produces artifacts. In that case, the filter author must set this property
to true
.
@default false
Padding can extend the size of the filter texture in all directions. That's useful when the filter "grows" the bounds of the object in any direction.
The resolution of the filter texture. "1" means stage resolution, "0.5" half the stage resolution. A lower resolution saves memory and execution time, but results in a lower output quality. Values greater than 1 are allowed; such values might make sense for a cached filter when it is scaled up. @default 1
The format of the filter texture. @default BGRA
The smoothing mode of the filter texture. @default bilinear
Caches the filter output into a texture.
An uncached filter is rendered every frame (except if it can be rendered from the
global render cache, which happens if the target object does not change its appearance
or location relative to the stage). A cached filter is only rendered once; the output
stays unchanged until you call cache
again or change the filter settings.
Beware: you cannot cache filters on 3D objects; if the object the filter is attached to is a Sprite3D or has a Sprite3D as (grand-) parent, the request will be silently ignored. However, you can cache a 2D object that has 3D children!
Clears the cached output of the filter. After calling this method, the filter will be processed once per frame again.
Dispatches an event to all objects that have registered listeners for its type. If an event with enabled 'bubble' property is dispatched to a display object, it will travel up along the line of parents, until it either hits the root object or someone stops its propagation manually.
Dispatches an event with the given parameters to all objects that have registered listeners for the given type. The method uses an internal pool of event objects to avoid allocations.
Disposes all resources that have been created by the filter.
If called with one argument, figures out if there are any listeners registered for the given event type. If called with two arguments, also determines if a specific listener is registered.
Does the actual filter processing. This method will be called with up to four input
textures and must return a new texture (acquired from the helper
) that
contains the filtered output. To to do this, it configures the FilterEffect
(provided via createEffect
) and calls its render
method.
In a standard filter, only input0
will contain a texture; that's the
object the filter was applied to, rendered into an appropriately sized texture.
However, filters may also accept multiple textures; that's useful when you need to
combine the output of several filters into one. For example, the DropShadowFilter
uses a BlurFilter to create the shadow and then feeds both input and shadow texture
into a CompositeFilter.
Never create or dispose any textures manually within this method; instead, get new textures from the provided helper object, and pass them to the helper when you do not need them any longer. Ownership of both input textures and returned texture lies at the caller; only temporary textures should be put into the helper.
Removes all event listeners with a certain type, or all of them if type is null. Be careful when removing all event listeners: you never know who else was listening.
Renders the filtered target object. Most users will never have to call this manually; it's executed automatically in the rendering process of the filtered display object.
Generated using TypeDoc
The FragmentFilter class is the base class for all filter effects in Starling. All filters must extend this class. You can attach them to any display object through the
filter
property.A fragment filter works in the following way:
process
method.FilterEffect
subclass that processes the input via fragment and vertex shaders to achieve a certain effect.alwaysDrawToBackBuffer
property.All of this is set up by the basic FragmentFilter class. Concrete subclasses just need to override the protected method
createEffect
and (optionally)process
. Multi-pass filters must also overridenumPasses
.Typically, any properties on the filter are just forwarded to an effect instance, which is then used automatically by
process
to render the filter pass. For a simple example on how to write a single-pass filter, look at the implementation of theColorMatrixFilter
; for a composite filter (i.e. a filter that combines several others), look at theGlowFilter
.Beware that a filter instance may only be used on one object at a time!
Animated filters
The
process
method of a filter is only called when it's necessary, i.e. when the filter properties or the target display object changes. This means that you cannot rely on the method to be called on a regular basis, as needed when creating an animated filter class. Instead, you can do so by listening for anENTER_FRAME
-event. It is dispatched on the filter once every frame, as long as the filter is assigned to a display object that is connected to the stage.Caching
Per default, whenever the target display object is changed in any way (i.e. the render cache fails), the filter is reprocessed. However, you can manually cache the filter output via the method of the same name: this will let the filter redraw the current output texture, even if the target object changes later on. That's especially useful if you add a filter to an object that changes only rarely, e.g. a TextField or an Image. Keep in mind, though, that you have to call
cache()
again in order for any changes to show up.@see starling.rendering.FilterEffect