Use a CAGradientLayer in SpriteKit?

Question

I created a CAGradientLayer, which works really fine. But my problem is, that I want to use it in SpriteKit as a background...

Is there a possibility to realize it ? Maybe by putting it in a SKSpriteNode ?

Thanks in advance

EDIT:

Unfortunately theres an error message:

May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextClipToRect: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextTranslateCTM: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextScaleCTM: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextDrawLinearGradient: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. May 28 19:08:19 amirs-mbp Gradient[2845] : CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

Refer this https://stackoverflow.com/questions/18894493/making-a-skscenes-background-transparent-not-working-is-this-a-bug/24494346#24494346 — Suresh, Oct 05 '16 at 14:42

score 2 · Answer 1 · answered Apr 05 '15 at 06:35

2

I think you'll have much better luck with this:

https://github.com/braindrizzlestudio/BDGradientNode

answered Apr 05 '15 at 06:35

Ian McKay

76
7

gabuh · Answer 2 · 2014-05-28T17:37:14.123

1

First convert the layer to UIImage*:

- (UIImage *)imageFromLayer:(CALayer *)layer
{

    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
        UIGraphicsBeginImageContextWithOptions([layer frame].size, NO, [UIScreen mainScreen].scale);
    else
        UIGraphicsBeginImageContext([layer frame].size);

    [layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return outputImage;
}

And then init a SKSpriteNode with it:

SKSpriteNode* node = [SKSpriteNode spriteNodeWithColor:[UIColor colorWithPatternImage:image] 
                                   size:yourLayer.bounds.size]

edited May 28 '14 at 17:37

answered May 28 '14 at 16:46

gabuh

1,166
8
15

Thanks for your quick response :) Unfortunately it doesn't work... I've got an error message, which I posted above as EDIT – appcodix May 28 '14 at 17:14
It must be that you are creating the context in the wrong place. you'll need to locate your drawing code within the -drawRect: method of a UIView (or –drawInContext: of a CALayer). That's because the currentcontext is nil until it's required. – gabuh May 28 '14 at 17:57
Forget my last comment... it's weird because UIGraphicsGetCurrentContext() should not be nil between UIGraphicsBeginImageContext and UIGraphicsEndImageContext... Maybe the cause is the interaction with SpriteKit. – gabuh May 28 '14 at 18:03

score 0 · Answer 3 · answered Jan 29 '15 at 20:43

This function works for me for creating a SpriteNode from CAGradientLayer. Please note it is a function of GameScene, so that is the 'self.frame' context that it is referring to get the right size of the gradient.

func layerToSKSpriteNode(layer : CALayer) -> SKSpriteNode
{
    var view = UIView()
    layer.frame = self.frame
    view.layer.addSublayer(layer)

    UIGraphicsBeginImageContext(self.frame.size)
    view.layer.renderInContext(UIGraphicsGetCurrentContext())
    var bgImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return SKSpriteNode(texture: SKTexture(image: bgImage))
}

Use a CAGradientLayer in SpriteKit?

3 Answers3