SpriteKit中的水效果使用模糊和阈值

Question

I am trying to make a water effect using SpriteKit similar to the answer in this link. Water physics

How can I add a blur effect and some sort of "threshold" filter to get that look?

I got the blur to work like this, but am not sure how to add a "threshold" filter.

override func didMoveToView(view: SKView) {

    let effectNode = SKEffectNode()

    let circleOne = SKSpriteNode(imageNamed: "circle1")
    circleOne.position = CGPointMake(CGRectGetMidX(self.frame) - 20, CGRectGetMidY(self.frame))

    let circleTwo = SKSpriteNode(imageNamed: "circle1")
    circleTwo.position = CGPointMake(CGRectGetMidX(self.frame) + 40, CGRectGetMidY(self.frame))

    effectNode.filter = blur()

    effectNode.addChild(circleOne)
    effectNode.addChild(circleTwo)

    addChild(effectNode)
}

func blur() -> CIFilter {
    let filter = CIFilter(name: "CIGaussianBlur")
    filter!.setDefaults()
    filter!.setValue(NSNumber(float: 10.0), forKey: "inputRadius")
    return filter!
}

Thank you for your help!

Answer 1

So I found this Threshold filter that seems to work pretty well.

void main() {
lowp vec4 color = texture2D(u_texture,v_tex_coord);

if(color.w > 0.1) {
    color = vec4(251.0/255.0, 246.0/255.0, 0.0/255.0, 1.0);
} else {
    color = vec4(0.0, 0.0, 0.0, 0.0);
}

gl_FragColor = color; }

The frame rate is fairly terrible when I reach about 30-50 sprites colliding with each other unfortunately.

In order to help out a little, I got rid of the blur and just made the actual sprite images blurred, but it didn't help too much.

I did some reading about SpriteKit's Box2d implementation, and unfortunately it seems to not be very efficient, so I might be stuck with it.

If anyone has a better solution, I'd love to hear your thoughts!

Here's what its looking like so far.