PackagePBLabs.Rendering2D
Interfacepublic interface IDrawManager2D
ImplementorsBaseSceneComponent

Interface for rendering 2D scenes. Objects can be drawn in Flash using BitmapDatas or DisplayObjects. A rendering component might be implemented using either method (for instance, an isometric tilemap might composite everything into a BitmapData while a simpler 2d sprite system might use the DisplayObject hierarchy). However, you may want to introduce a rendering effect that requires the opposite approach. This API provides a simple way for all these rendering techniques to co-exist. It provides hooks for both DisplayObjects and BitmapData to be drawn. During rendering, each visible IDrawable2D has its OnDraw method called. The IDrawable2D can then inspect the state of the IDrawManager2D and call DrawDisplayObject and/or DrawBitmapData one or more times to render itself. In the case of complex sets of objects - like a tile map or particle system - we assume that they will be grouped into a single IDrawable2D and drawn efficiently in an object-specific way by that object before being submitted to the IDrawManager2D. This manager is more of a compositer than a high performance rendering API. It additionally provides methods to transform from world space to screen space and back. It supports isometric perspectives by allowing an altitude to be specified when transforming from world to screen space. In an ortho perspective, the altitude is ignored. You will notice that there is not a way to register normal scene objects with the manager. It is assumed that the manager will use a spatial database to determine what needs to be drawn. There is a way to note "always drawn" items. This functionality exists to support things that should always have the opportunity to draw, for instance a physics debug visualization or a background layer. We briefly describe the four rendering possibilities and how to deal with them: The scene is drawn into DisplayObjects and the IDrawable2D submits a DisplayObject. In this case, add it to the end of the display hierarchy. The scene is drawn into DisplayObjects and the IDrawable2D submits a BitmapData. In this case, make a Sprite and draw the BitmapData into its graphics object. Add the sprite normally. The scene is drawn into a BitmapData and the IDrawable2D submits a DisplayObject. All DisplayObjects implement IBitmapDrawable, so draw the DisplayObject into the BitmapData using BitmapData.draw(). The scene is drawn into a BitmapData and the IDrawable2D submits a BitmapData. All BitmapDatas implement IBitmapDrawable, so draw the BitmapData into the BitmapData using BitmapData.draw().


Public Properties
 PropertyDefined by
  LastDrawnItem : IDrawable2D
[read-only] During drawing, set to the last drawn item or null if there is none (if this is the first rendered object or first interstitial call).
IDrawManager2D
  NextDrawnItem : IDrawable2D
[read-only] During drawing, set to the item that will be drawn next, or null if we are at the end of the draw list.
IDrawManager2D
Public Methods
 MethodDefined by
  
AddAlwaysDrawnItem(item:IDrawable2D):void
Add an item that will always receive an opportunity to render.
IDrawManager2D
  
AddInterstitialDrawer(item:IDrawable2D):void
Some renderers need to draw in between everything else in order to sort right, and it isn't possible to manually add IDrawable2Ds at every location.
IDrawManager2D
  
CopyPixels(bitmapData:BitmapData, offset:Point):void
IDrawManager2D
  
DrawBitmapData(bd:BitmapData, m:Matrix):void
Called from IDrawable2D.OnDraw to render a BitmapData to the screen.
IDrawManager2D
  
DrawDisplayObject(object:DisplayObject):void
Called from IDrawable2D.OnDraw to render a DisplayObject to the screen.
IDrawManager2D
  
GetBackBuffer():BitmapData
Get the current results of rendering as a BitmapData.
IDrawManager2D
  
RemoveAlwaysDrawnItem(item:IDrawable2D):void
Remove an item added by AddAlwaysDrawnItem.
IDrawManager2D
  
RemoveInterstitialDrawer(item:IDrawable2D):void
Remove an interstitial drawer previously registered with AddInterstitialDrawer.
IDrawManager2D
  
TransformScreenToWorld(p:Point):Point
Transform a screen position in pixels into a worldspace coordinate.
IDrawManager2D
  
TransformWorldToScreen(p:Point, altitude:Number = 0):Point
Transform a world position to screen space in pixels.
IDrawManager2D
Property detail
LastDrawnItemproperty
LastDrawnItem:IDrawable2D  [read-only]

During drawing, set to the last drawn item or null if there is none (if this is the first rendered object or first interstitial call).

Implementation
    public function get LastDrawnItem():IDrawable2D
NextDrawnItemproperty 
NextDrawnItem:IDrawable2D  [read-only]

During drawing, set to the item that will be drawn next, or null if we are at the end of the draw list.

Implementation
    public function get NextDrawnItem():IDrawable2D
Method detail
AddAlwaysDrawnItem()method
public function AddAlwaysDrawnItem(item:IDrawable2D):void

Add an item that will always receive an opportunity to render.

Parameters
item:IDrawable2D
AddInterstitialDrawer()method 
public function AddInterstitialDrawer(item:IDrawable2D):void

Some renderers need to draw in between everything else in order to sort right, and it isn't possible to manually add IDrawable2Ds at every location. For instance, a particle system in an isometric perspective has to have an opportunity to draw before and after every object in the scene in order to sort correctly. It would be a huge headache to manually place IDrawable2Ds at every particle location. This registered an "interstitial" drawer with a scene, which is a IDrawable2D which gets called back between every object, as well as at the beginning and ending of rendering. It can use the LastDrawnItem and NextDrawnItem properties to determine what to draw at each call.

Parameters
item:IDrawable2D
CopyPixels()method 
public function CopyPixels(bitmapData:BitmapData, offset:Point):voidParameters
bitmapData:BitmapData
 
offset:Point
DrawBitmapData()method 
public function DrawBitmapData(bd:BitmapData, m:Matrix):void

Called from IDrawable2D.OnDraw to render a BitmapData to the screen. The BitmapData is placed via the passed matrix. May be called multiple times.

Parameters
bd:BitmapData
 
m:Matrix
DrawDisplayObject()method 
public function DrawDisplayObject(object:DisplayObject):void

Called from IDrawable2D.OnDraw to render a DisplayObject to the screen. Uses the transform on the DisplayObject for rendering. May be called multiple times.

Parameters
object:DisplayObject
GetBackBuffer()method 
public function GetBackBuffer():BitmapData

Get the current results of rendering as a BitmapData. Useful for post processing effects (like glow/blur/motion trails).

Returns
BitmapData
RemoveAlwaysDrawnItem()method 
public function RemoveAlwaysDrawnItem(item:IDrawable2D):void

Remove an item added by AddAlwaysDrawnItem.

Parameters
item:IDrawable2D
RemoveInterstitialDrawer()method 
public function RemoveInterstitialDrawer(item:IDrawable2D):void

Remove an interstitial drawer previously registered with AddInterstitialDrawer.

Parameters
item:IDrawable2D

See also

AddInterstitialDrawer
TransformScreenToWorld()method 
public function TransformScreenToWorld(p:Point):Point

Transform a screen position in pixels into a worldspace coordinate. We currently only support isometric or orthographic projections, so cannot reconstruct a Z coordinate. Results can be assumed to have an altitude of zero.

Parameters
p:Point

Returns
Point
TransformWorldToScreen()method 
public function TransformWorldToScreen(p:Point, altitude:Number = 0):Point

Transform a world position to screen space in pixels. Altitude can be passed, but is only meaning in non-orthographic projections. The results from this can be passed directly into the x/y properties on a DisplayObject.

Parameters
p:Point
 
altitude:Number (default = 0)

Returns
Point