Horizontally mirror a SKSpriteNode texture

Question

I'm developing an iOS7 game with the new API called Sprite Kit. I'd like to horizontally rotated a SKSpriteNode image/texture. I've tried it by first mirroring the image, then creating a SKTexture and finally applying it to the SKSpriteNode but it doesn't work. Is there some way to do this? Or I should have to different images?

Answer 1

You can use this code to flip among x-axis:

spriteNode.xScale = spriteNode.xScale * -1;

but be careful you can lose some of physicsbody's property, I highly suggest u to use xScale in this way:

spriteNodeBody = [SKNode node];
spriteNodeBody.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:spriteNode.size];
spriteNodeBody.physicsBody.categoryBitMask = CNPhysicsCategoryPlayer;
spriteNodeBody.physicsBody.collisionBitMask = CNPhysicsCategoryBall;

[spriteNodeBody addChild:spriteNode];
[self addChild:spriteNodeBody];

And now you can safely use:

    spriteNode.xScale = spriteNode.xScale * -1;

Answer 2

If you're just trying to flip the sprite along an axis, you can do something like this:

sprite.xScale = -1.0;

Answer 3

I use this for my rightHanded or leftHanded sprites:

with some help from here Horizontal Flip of a frame in Objective-C

BOOL leftHanded = YES;

SKSpriteNode *sprite;

if (leftHanded) {  //my textures point east, so I flip vertically
    SKTexture *texture = [SKTexture textureWithImageNamed:@"figure-step0"];
    CIFilter *filter = [CIFilter filterWithName:@"CIAffineTransform"];
    [filter setValue:[CIImage imageWithCGImage:[texture CGImage]] forKey:kCIInputImageKey];

#ifdef IOS_BLOCK  //set these up with defines
    CGAffineTransform flipTransform = CGAffineTransformMakeScale(1.0f, -1.0f); // vert
    [filter setValue:[NSValue valueWithBytes:&flipTransform
                                objCType:@encode(CGAffineTransform)]
                                forKey:@"inputTransform"];
#else //OSX_BLOCK
    NSAffineTransform* flipTransform = [NSAffineTransform transform];
    [flipTransform scaleXBy:1.0f yBy: -1.0f]; // vert
    [filter setValue:flipTransform forKey:@"inputTransform"];
#endif
    sprite = [SKSpriteNode spriteNodeWithTexture:
                     [texture textureByApplyingCIFilter:filter]];
} else {
    sprite = [SKSpriteNode spriteNodeWithImageNamed:@"figure-step0"];
}

You can do the same for animation frames likewise. Works for iOS or OS X.

Answer 4

This is my solution written in Swift 2.x, usually I prefeer to use landscape mode for my games, so I write this extension:

extension SKTexture {
    class func flipImage(name:String,flipHoriz:Bool,flipVert:Bool)->SKTexture {
        if !flipHoriz && !flipVert {
            return SKTexture.init(imageNamed: name)
        }
        let image = UIImage(named:name)

        UIGraphicsBeginImageContext(image!.size)
        let context = UIGraphicsGetCurrentContext()

        if !flipHoriz && flipVert {
            // Do nothing, X is flipped normally in a Core Graphics Context 
            // but in landscape is inverted so this is Y
        } else
        if flipHoriz && !flipVert{
            // fix X axis but is inverted so fix Y axis
            CGContextTranslateCTM(context, 0, image!.size.height)
            CGContextScaleCTM(context, 1.0, -1.0)
            // flip Y but is inverted so flip X here
            CGContextTranslateCTM(context, image!.size.width, 0)
            CGContextScaleCTM(context, -1.0, 1.0)
        } else
        if flipHoriz && flipVert {
            // flip Y but is inverted so flip X here
            CGContextTranslateCTM(context, image!.size.width, 0)
            CGContextScaleCTM(context, -1.0, 1.0)
        }

        CGContextDrawImage(context, CGRectMake(0.0, 0.0, image!.size.width, image!.size.height), image!.CGImage)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext();
        return SKTexture(image: newImage)
    }
}

Usage:

let spriteTxt = SKTexture.flipImage(imageName, flipHoriz: true, flipVert: false)

P.S.: If you want the same function but to portrait mode please refeer to this answer