SpriteKit : sprite positioning

Question

I've found lately a tutorial on how to build a game like "flappy bird" using SpriteKit. Instead of implementing the tap-mechanism, I've used the device accelerometer to move the bird, right and left. My problem, now, is with generating pipes. The method used in the tutorial creates pipes on the x axe and not the y axe, which I want to do.

-(void)createPipes
{
   SKTexture* _pipeTexture1 = [SKTexture textureWithImageNamed:@"Pipe1"];
   _pipeTexture1.filteringMode = SKTextureFilteringNearest;
   SKTexture* _pipeTexture2 = [SKTexture textureWithImageNamed:@"Pipe2"];
   _pipeTexture2.filteringMode = SKTextureFilteringNearest;

   SKNode* pipePair = [SKNode node];
   pipePair.position = CGPointMake( self.frame.size.width + _pipeTexture1.size.width * 2,   0 );
   pipePair.zPosition = -10;

   CGFloat y = arc4random() % (NSInteger)( self.frame.size.height / 3 );

   SKSpriteNode* pipe1 = [SKSpriteNode spriteNodeWithTexture:_pipeTexture1];
   [pipe1 setScale:2];
   pipe1.position = CGPointMake( self.frame.size.width/2 -100, self.frame.size.height+250 );
   pipe1.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:pipe1.size];
   pipe1.physicsBody.dynamic = NO;
   [pipePair addChild:pipe1];

   SKSpriteNode* pipe2 = [SKSpriteNode spriteNodeWithTexture:_pipeTexture2];
   [pipe2 setScale:2];
   pipe2.position = CGPointMake( self.frame.size.width/2 +100, self.frame.size.height+250 );
   pipe2.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:pipe2.size];
   pipe2.physicsBody.dynamic = NO;
   [pipePair addChild:pipe2];

   SKAction* movePipes = [SKAction repeatActionForever:[SKAction moveByX:0 y:-2 duration:0.02]];
   [pipePair runAction:movePipes];

   [self addChild:pipePair];
 }

My idea is to generate pipes that fall from the "sky" and the bird has to move between the pipes to keep living. I hope that the description of my problem was very clear :) Thanks

Clarification : Pipes do fall from the "sky" but the problem lies with their positioning on the screen. When I run the project, there's no gap between the right pipe or the left one. I only see a giant pipe falling, filling, vertically, a good proportion of the screen.

score 0 · Answer 1 · answered Feb 23 '14 at 13:17

0

Thanks for linking the tutorial!

If you want the pipes to fall, then just let them fall! The pipes have physics bodies attached so they should fall down from the sky depending on their vertical position. There's no need to use the SKAction for moving the pipes then. However, you need to change their dynamic flag to YES so that gravitational force is applied. See Xcode reference:

A Boolean value that indicates whether the physics body is moved by the physics simulation. The default value is YES. If the value is NO, then the physics body ignores all forces and impulses applied to it. This property is ignored on edge-based bodies; they are automatically static.

answered Feb 23 '14 at 13:17

digitalbreed

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Actually the pipes do fall horizontally but the problem is with their positioning on the screen. WHen they fall, I can't see the end of the pipe for the right one or the beginning of the left one. – Sahbi Belgacem Feb 23 '14 at 15:48
Maybe I'm not quite getting what you're intending to do (share a screenshot maybe?!), but I want to share one idea nonetheless: Remember that the two pipes are children of parent `_pipePair` and relatively positioned to the parent. The parent is still positioned at the right edge of the screen, like in the tutorial and you ADD additional pixel space on top of that. Maybe you need to update that to suit your needs. – digitalbreed Feb 23 '14 at 16:59
Yes exactly I need to change the position of the sprites to suit my need. I'm trying since yesterday to find the right values for the pipes. See my screenshot [link] (https://www.dropbox.com/s/pnfukiwugtnme45/Screenshot%202014.02.23%2019.27.22.png) – Sahbi Belgacem Feb 23 '14 at 18:30
I tried to write an answer as text but eventually I guess a picture says more than a thousand words. Take a look here to see how I would arrange the nodes. http://i58.tinypic.com/jkg3mv.png Note that the text "(-1 = nothing, 1 = full width)" actually should be "(-1 = nothing, 0 = full width)" – digitalbreed Feb 23 '14 at 20:15
...and I didn't expect this image service to change my picture from PNG to JPG. I give up. Contact me directly if necessary. – digitalbreed Feb 23 '14 at 20:17
At least now, I can see the end of the right pipe. Thank you man for your help. I really appreciate it. :) – Sahbi Belgacem Feb 23 '14 at 20:36
btw, how can I contact you directly..?? I didn't find any contact info on your profile..! – Sahbi Belgacem Feb 23 '14 at 20:55
I have a contact form on my page and you can leave a comment on the blog post. – digitalbreed Feb 25 '14 at 16:32

score 0 · Accepted Answer · answered Feb 24 '14 at 18:48

I have finally found a solution. By changing the values of pipes position as follow, I've managed to make them appear properly on the screen.

SKSpriteNode* pipe1 = [SKSpriteNode spriteNodeWithTexture:_pipe1];
pipe1.position = CGPointMake( (-0.39*pipe1.size.width), 0 );
SKSpriteNode* pipe2 = [SKSpriteNode spriteNodeWithTexture:_pipe2];
pipe2.position = CGPointMake(self.frame.size.width  *1.8, 0 );

The result ==> picture

The big challenge now is find a way to make the position of the pipes somehow random. :)

SpriteKit : sprite positioning

2 Answers2