How Do I Blur a Scene in SpriteKit?
To add to this by using @Bendegúz's answer and code from http://www.bytearray.org/?p=5360
I was able to get this to work in my current game project that's being done in IOS 8 Swift. Done a bit differently by returning an SKSpriteNode instead of a UIImage. Also note that my unwrapped currentScene.view! call is to a weak GameScene reference but should work with self.view.frame based on where you are calling these methods. My pause screen is called in a separate HUD class hence why this is the case.
I would imagine this could be done more elegantly, maybe more like @jemmons's answer. Just wanted to possibly help out anyone else trying to do this in SpriteKit projects written in all or some Swift code.
func getBluredScreenshot() -> SKSpriteNode{
create the graphics context
UIGraphicsBeginImageContextWithOptions(CGSize(width: currentScene.view!.frame.size.width, height: currentScene.view!.frame.size.height), true, 1)
currentScene.view!.drawViewHierarchyInRect(currentScene.view!.frame, afterScreenUpdates: true)
// retrieve graphics context
let context = UIGraphicsGetCurrentContext()
// query image from it
let image = UIGraphicsGetImageFromCurrentImageContext()
// create Core Image context
let ciContext = CIContext(options: nil)
// create a CIImage, think of a CIImage as image data for processing, nothing is displayed or can be displayed at this point
let coreImage = CIImage(image: image)
// pick the filter we want
let filter = CIFilter(name: "CIGaussianBlur")
// pass our image as input
filter.setValue(coreImage, forKey: kCIInputImageKey)
//edit the amount of blur
filter.setValue(3, forKey: kCIInputRadiusKey)
//retrieve the processed image
let filteredImageData = filter.valueForKey(kCIOutputImageKey) as CIImage
// return a Quartz image from the Core Image context
let filteredImageRef = ciContext.createCGImage(filteredImageData, fromRect: filteredImageData.extent())
// final UIImage
let filteredImage = UIImage(CGImage: filteredImageRef)
// create a texture, pass the UIImage
let texture = SKTexture(image: filteredImage!)
// wrap it inside a sprite node
let sprite = SKSpriteNode(texture:texture)
// make image the position in the center
sprite.position = CGPointMake(CGRectGetMidX(currentScene.frame), CGRectGetMidY(currentScene.frame))
var scale:CGFloat = UIScreen.mainScreen().scale
sprite.size.width *= scale
sprite.size.height *= scale
return sprite
}
func loadPauseBGScreen(){
let duration = 1.0
let pauseBG:SKSpriteNode = self.getBluredScreenshot()
//pauseBG.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
pauseBG.alpha = 0
pauseBG.zPosition = self.zPosition + 1
pauseBG.runAction(SKAction.fadeAlphaTo(1, duration: duration))
self.addChild(pauseBG)
}
What you're looking for is an SKEffectNode
. It applies a CoreImage filter to itself (and thus all subnodes). Just make it the root view of your scene, give it one of CoreImage's blur filters, and you're set.
For example, I set up an SKScene
with an SKEffectNode
as it's first child node and a property, root
that holds a weak reference to it:
-(void)createLayers{
SKEffectNode *node = [SKEffectNode node];
[node setShouldEnableEffects:NO];
CIFilter *blur = [CIFilter filterWithName:@"CIGaussianBlur" keysAndValues:@"inputRadius", @1.0f, nil];
[node setFilter:blur];
[self setRoot:node];
}
And here's the method I use to (animate!) the blur of my scene:
-(void)blurWithCompletion:(void (^)())handler{
CGFloat duration = 0.5f;
[[self root] setShouldRasterize:YES];
[[self root] setShouldEnableEffects:YES];
[[self root] runAction:[SKAction customActionWithDuration:duration actionBlock:^(SKNode *node, CGFloat elapsedTime){
NSNumber *radius = [NSNumber numberWithFloat:(elapsedTime/duration) * 10.0];
[[(SKEffectNode *)node filter] setValue:radius forKey:@"inputRadius"];
}] completion:handler];
}
Note that, like you, I'm using this as a pause screen, so I rasterize the scene. If you want your scene to animate while blurred, you should probably setShouldResterize:
to NO
.
And if you're not interested in animating the transition to the blur, you could always just set the filter to an initial radius of 10.0f
or so and do a simple setShouldEnableEffects:YES
when you want to switch it on.
See also: SKEffectNode class reference
UPDATE:
See Markus's comment below. He points out that SKScene
is, in fact, a subclass of SKEffectNode
, so you really ought to be able to call all of this on the scene itself rather than arbitrarily inserting an effect node in your node tree.