I have a node and I've fixed the position of that node. Then I added a sprite as a child of that node (which I've added earlier). After that I try to rotate the node by some angle.
As a result sprite is also rotating and its center point is position of node. Now my question is, how can I get the position of sprite?
Sprite position is the same - "Center of node".
I don't understand what exact position do you want to evaluate. And I hope follow methods will help you:
Each CCNode (and all sublcasses CCSprite, CCLayer etc) have follow helpers that very useful for evaluation coords between nodes:
- (CGPoint)convertToNodeSpace:(CGPoint)worldPoint;
- (CGPoint)convertToWorldSpace:(CGPoint)nodePoint;
- (CGPoint)convertToNodeSpaceAR:(CGPoint)worldPoint;
- (CGPoint)convertToWorldSpaceAR:(CGPoint)nodePoint;
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I have created a SCNNode object on a SCNPlane object. Both objects are added to the scene view root node, like below:
scView.scene.rootNode.addChildNode(ballNode)
scView.scene.rootNode.addChildNode(planeNode)
Now, my issue is that the ball node is moving out of the plane node boundary.
When I tried to add ballNode as planeNode's child then, the ball node is not getting added to a plane as expected. It behaves very strangely.
Basically, I need to restrict the movement of ballNode within planeNode area. How can I do it?
Great question!
When adding a child node to another node, there are no constraints being implicitly applied to the child, aside from existing within the infinite coordinate space of the parent node.
While changing the transform (eg position) of the parent node will directly apply to all child nodes, each child node can still freely transform within the parent nodes local coordinate space.
It'd be a good idea to read the SCNNode docs if you haven't already, as it covers the foundational aspects.
To do what you want, when moving the ball in your gameloop, you will need to manually check whether or not that ball is outside the boundary you are trying to enforce, and change its position accordingly.
Depending on your desired outcome, you may want to also check out SCNPhysicsBody as a way to construct your scene with implied physical boundaries.
I'm trying to add nodes to my scene view, but all of the nodes have a zero position, but different placements.
Each node has a position (0,0,0) but, on the scene view, this node has a different placement. Also, I can`t find the distance between nodes because each node has a position (0, 0, 0). Please explain to me what is wrong with my nodes.
If you want to fetch the real position of a node try this:
node.presentation.worldPosition
This should always return you the effective position of the node as seen on screen.
The problem was in 3d object, the original position of the 3d was not centered. I upload each 3c object to Blender and change original position to (0,0,0)
Hello dear developers...
One of my function gets a starting point and an ending point. Both are 'CGPoint's. I want to create a a sprite node at the starting point and then, I want to stretch that node to the ending point. How can I do that? Attention I don't want to change it's position, I want to resize it until X-Axis touches the ending point. Thanks in advance...
Hi im pretty new to programming and I have encountered a small issue. I am creating a simple game which has a score label. However, the score label is covered whenever a downward scrolling obstacle passes. I would like for the score label to not be covered by the obstacles.Is there a way i can change the sprite hierarchy in spritekit? Thanks
I would recommend creating a node for the static stuff that should be fixed on screen (like a game HUD). Then you set this node's zPosition to be higher then the game play node (where all game objects are placed and manipulated).
This makes it also easier implementing a camera or moving the game play node if needed without the score label or any other fixed hud element moving as well.
So you will have something like this :
SKNode *hudNode = [SKNode node];
hudNode.zPosition = 1000;
[hudNode addChild:scoreLabel];
SKNode *gamePlayNode = [SKNode node];
gamePlayNode.zPosition = 0; // Not mandatory as it defaults to 0 but I put this here for clarification
[self addChild:hudNode]; // self is your scene instance
[self addChild:gamePlayNode];
You can change the zPosition property of your label node, by making it 100 it will be above all other nodes (default value is 0.0):
labelNode.zPosition = 100;
Nodes are drawn in the order they are added to the scene (or parent node). You can change the order in which nodes are drawn by setting their zPosition property.
From Apple's documentation...
...The z position is the node’s height relative to its parent node, much as a node’s position
property represents its x and y position relative to parent’s
position. So you use the z position to place a node above or below the
parent’s position.
When you take z positions into account, here is how the node tree is
rendered:
Each node’s global z position is calculated.
Nodes are drawn in order from smallest z value to largest z value.
If two nodes share the same z value, ancestors are rendered first, and siblings are rendered in child order.
You can also use zPosition to optimize rendering performance...
...it might be better if Sprite Kit could gather all of the nodes that share the same texture and drawing mode and and draw them with a single drawing pass. To enable these sorts of optimizations, you set the view’s ignoresSiblingOrder property to YES.
so I have a ball (sprite subclass) that can be dragged around the screen and updates it body to tell the world its position.
The problem is, when I apply a force to the ball while the ball is being touched (thus being controlled by a finger), I have two pieces of code fighting against each other to update the sprite's visual position.
The world stepper is trying to follow through the physics and update the ball's position. The touch methods however are also trying to update the ball's body and graphic position. Ideally, when touched I would like to kill off any physics affecting the ball.
So what exactly should I be trying to do to consolidate this? This is also creating issues for collisions and filtering. Any help appreciated. Thanks
Do you want the ball to have an accurate physics simulation? If not, you could always use the SetTransform method of the b2body class like this.
CGPoint ballLocation = ;//use the touched location for this
b2Vec2 vecBallLocation = b2Vec2(ballLocation.x / 32, ballLocation.y / 32);//calculate this on your own
b2Body * ballBody = ;//replace this variable with your ball's b2Body;
ballBody->SetTransform(vecBallLocation, ballBody->GetAngle());
Do not set the ball sprite's position manually. Leave this up to the physics simulation. Your code will get really messy over time if you have to keep track of what sprites you set the position of manually and which ones use the physics simulation to update their positions. This way is also much easier.
When the physics object is being dragged, set its velocity and angular velocity to 0,0 before running the physics step simulation. You may also want to temporarily get the physics object's position, then step, then set the body's position back, then apply whatever touch dragging offset you got from moving the finger to the body.