My game is based on two screens (A & B) side by side, but the device screen can only display one of them at a time.
A is for example at position (0, 0) and B is at (320, 0)
I tried two solutions to switch from A to B:
First, I place the whole scene into one node, the MainNode. To switch
from A to B, simply set MainNode position to (0, -320).
Other solution, more elegant IMHO (but not for LearnCoco2D who uses the Coco2D library), is to move the scene anchorPoint to (0, -1)
Now, if I want to go from A to B with an animation, these two solutions must be adapted:
By using a SKAction
[Main runAction:[SKAction moveToY:-320 duration:0.1]];
By animating anchorPoint in the update method
if(anchorY > -1) anchorY -= 0.1;
These two solutions works (despite a linear SKAction::timingMode does not render a linear translation properly), but I wonder which is the best in term of optimization, and elegance. Documentation is welcomed ;)
EDIT:
Apparently, my question is not clear (maybe due to my english level).
In few words, my question is: What exactly are the best practices for scrolling a scene?
I am surprised (0, -1) doesn't throw a huge exception. According to the docs you get a range from 0 to 1. This could cause issues in the future. See the docs here
Changing your position sounds like a more elegant way of handling it. however changing it to negative -320 in a span of 1/10th of a second is rather quick and could explain why it looks funny. Also if you aren't making sure you are only calling that once it will look really odd. I would make sure that it is only getting called once and maybe using a bool to toggle if it should be moved instead of checking a position.
If you are going back and forth a lot from one screen to another this might be an ok solution. However if you are looking to scale this to a much larger map where you are going to transition several times to new screens I would recommend a different approach all together. Like creating a new node off screen when you need it and transition a parent node then pop the old node off.
I hope that helps.
Edit
Now that the question is "what exactly are the best practices for scrolling a scene".
I would recommend what LearnCoco2D mentioned in the comment and what I eluded to in my original answer.
Add a sub node to your scene that will handle positioning (lets call it mapNode)
Add any sprites that represent the scene to the mapNode
Move just the MapNode position on update
In the past I have built my Scenes in a similar fashion and have handled the scene position based on the player position in the update loop. I was able to keep the player in the center of the screen as he walked around the map. Might be getting off subject, but that is what I found the best practice for handling scrolling a scene from my experience. The project I am working on can be viewed here
I hope that answers your question.
Related
In my game, the size of the level can be larger than the screen of the phone and the camera will follow the player around the level, so there can be a decent amount of content(such as SKEmitterNodes) in the scene that is not visible at any given time. I've been reading through some of the SpriteKit documentation and found this quote in the SMEmitterNode section:
"Consider removing a particle emitter from the scene when it is not
visible onscreen. Add it just before it becomes visible."
Is this something that can be done in my type of game design? I don't want the nodes to be completely removed since they will eventually be put on the screen, but is there a good way for me to add/remove the EmitterNodes (or other SpriteNodes) that are a certain distance from the screen/is this a good idea to do? I'm looking to improve my frame-rate and don't want costly nodes like SMEmitterNodes working while they're not even being displayed, but will adding/removing them as the player moves around reduce the performance?
Here is the idea I currently have: create a rectangle that extends a certain distance around the screen and detect when a node comes into that rectangle, and if it's not already added to the scene, go ahead and add it. Thank you for any suggestions.
SKNodes really aren't a problem because when they are off screen they are not being rendered anyway, just evaluated. So the main thing to worry about with SKNodes are any physics bodies attached to them,
SKEmitterNodes however require some processing power, and that is why apple is recommending not having them emit if they are not on screen. I would just subclass my SKScene class, and do a checks only on SKEmitterNodes whether or not they are in frame, and emit based on that.
So, I would throw all your SKEmitterNodes into a container like an array, and have a loop function to have the node do a CGRectIntersectsRect check based on your camera location and viewable screen size. and if they intersect, add it to the scene, if not remove it from the scene. The array will keep a strong reference so you do not have to worry about it deiniting on you
I am making a game using cocos2d and SpriteBuilder. There is a hero sprite and coins, that should be collected by him. That's a horizontal scrolling game, so every time hero touches a coin, this coin changes it's x-coordinate 2000px to the right and new y-coordinate is generated at random. Using update method I move it to the visible area as a "new" coin. But when hero flyies by and doesn't collect it ,coin must change coordinates only when it's already off the screen, so I tried this solution:
-(void)update:(CCTime)delta{
_coin.position=ccp(_coin.position.x - delta * scrollSpeed, _coinY);
if (CGRectIntersectsRect(_hero.boundingBox,_coin.boundingBox)) {
_coinY=arc4random() % 801 + 100;
_coin.position=ccp(_coin.position.x + 2000.f,_coinY);
}
else if(_hero.position.x >= _coin.position.x + 150){
_coinY=arc4random() % 801 + 100;
_coin.position=ccp(_coin.position.x + 2000.f,_coinY);
}
It works,but after that I found a small bug(I am not sure, whether it's related to this code) : sometimes, when hero touches coin, hero is like pushed away to the left. I have no idea why.
How to fix it?
Is that way, that I am using for coin ,right?
I see 2 issues with your approach:
1. Hero bounces of the coin.
To fix this you need to make your coin a sensor. This way you will still be notified about collisions, but the hero will simply pass through the coin without actually hitting it.
I'm not sure if you can set this in SpriteBuilder, but probably you can enumerate all coins after loading the scene and set sensor property to YES:
coin.physicsBody.sensor = YES;
Things like this is one of the reasons I believe you first need to learn pure Cocos2D and only then use tools making your life easier such as SpriteBuilder. Which is a great tool, but in some cases you still need know what happens behind the scenes.
2. You're mixing physics with things like CGRectIntersectsRect
If you're using physics engine you need to detect collisions via collision delegate and not by checking CGRectIntersectsRect in update:.
It is hard to explain how to do this in a few sentences, so here is a nice tutorial that shows how to detect collisions in Cocos2D v3 and of course there is a chapter about this in my book.
By the way you shouldn't use update:at all when manipulating physics nodes, use fixedUpdate: instead.
I hope this will help you to solve your issue.
I'm trying to do a menu like the one that "Contre Jour" game has, with 3 elements spinning in a circle when user drags left and right. I'm using CALayers with CATransforms to position them in a 3d spinning wheel (no problem so far).
I need a way (maybe with NSTimers?) to calculate in-between values, because CoreAnimation just interpolates values, but if you NSLog them, it's just gonna show the start and the end, or just the end. I need all the in-between values, I need to snap the wheel movement when I release the finger (touches ends)in one position (there are 3 elements, each one shoud be at 120 degrees.
My guess and am quite sure I'm correct is that they are using a game engine such as Unity3D or Cocos2D or any other of the many to manage their sprites, animations, textures, physics and basically everything. Trying to replicate it outside of game engine will most likely result in crummy performance and a lot of hair pulling. I would suggest looking into a dedicated game engine and give it a shot there.
I am not sure I understand exactly what Contre Jour does with the spinners, anyway, I think that a reasonable approach for your case is using a UIPanGestureRecognizers to update the status of your spinning wheels according to the panning.
Now, it is not clear what you do to animate the spinning wheel (if you could provide some code, this would help understanding exactly what you are trying to do), but the idea would be this: instead of specifying an animation ending point far away from the starting point (and letting Core Animation do all the handling for you, even when the dragging has stopped), you would only modify the status of the spinning wheel in small increments.
If your only issue is stopping the animation when the dragging stops, you could try calling removeAnimationForKey on your layer to halt a specific animation.
Look into CADisplayLink. This works very much like an NSTimer, except its refresh rate is tied to that of the display, so your animations will be smoother than if you were to use timers. This will allow you to calculate all the in-between values and update your control.
I'm not clear what you are asking, but I do have one insight for you: To get the in-between values of an in-flight animation, query the layer's presentationLayer property. the property that's being animated will have a value that's a close approximation of it's on-screen appearance at the moment you fetch the value.
I've been suffering from an issue regarding the implementation of orienting characters in a game I'm implementing using Ogre3D and Bullet physics.
What I have: A Direction Vector that the character is moving in, along with its current orientation.
What I need: To set the orientation of the character to face the way it is moving.
I have a snippet of code that sort of does what I want:
btTransform src = body->getCenterOfMassTransform();
btVector3 up = BtOgre::Convert::toBullet(Ogre::Vector3::UNIT_X);
btVector3 normDirection = mDirection.normalized();
btScalar angle = acos(up.dot(normDirection));
btVector3 axis = up.cross(normDirection);
src.setRotation(btQuaternion(axis, angle));
body->setCenterOfMassTransform(src);
Where 'body' is the rigidbody I'm trying to orient.
This snippet has a couple of problems however:
1) When changing direction, it tends to 'jitter' i.e. it rapidly faces one way, then the opposite for a second or so before correcting itself to the orientation it is supposed to be at.
2) Most times that the code is run I get an assertion error from Bullet's btQuaternion on
assert(d != btScalar(0.0));
Can anyone help?
Thanks!
I think you shouldn't use functions like 'acos' for such things, as it may cause some inconsistencies in border-cases as the 180 vs 0 rotation mentioned above. You can also get high numerical error for such data.
The second thing is that - in general - you should avoid setting explicit position and rotation in physics engines, but rather apply forces and torques to make your body moving as you want. Your current approach may work perfectly now, but when you add another object and force you character to occupy the same space, your simulation will explode. And at this stage it's very hard to fix it, so it's better to do it right from start :) .
I know that finding correct force/torque can be tricky but it's the best way to make your simulation consistent.
I feel stupid asking this question, but I can not find a clear answer anywhere (or much of an answer at all) so I feel I must ask. Is there anyone out there who can explain clearly how the parallaxRatio of CCParallaxNode works?
I have checked the source of CCParallaxNode and it does not explain it at all. I have searched the internet and stackOverflow extensively. I have tried to do good old trial and error. I'm still confused.
[parallaxLayer addChild:backgroundEffect_subtleRed z:100 parallaxRatio:ccp(0.5, 0.5) positionOffset:backgroundEffect_subtleRed.position];
In this piece of code I am trying to add a particle emitter to a parallaxLayer and have it move somewhat like you would expect an object on a parallax layer to move. Unfortunately I do not see the particles at all. I have had this problem anytime I try to add anything to a parallaxNode when I want it to move. I have been using CCParallaxNode to create static UI layers, but have not been able to use them for what they were built to do.
In summary:
parallaxRatio takes a CGPoint. What do the floats in the CGPoint apply to? Are they ratios of x and y in relation to the window? Are they (parallaxLayerMovementInRelationTo, parentNode)? A working piece of example code would be very helpful.
Thank you.
To quote from a cocos2d book I own:
[paraNode addChild:para1 z:1 parallaxRatio:CGPointMake(0.5f, 0) positionOffset:topOffset];
[paraNode addChild:para2 z:2 parallaxRatio:CGPointMake(1, 0) positionOffset:topOffset];
[paraNode addChild:para3 z:4 parallaxRatio:CGPointMake(2, 0) positionOffset:midOffset];
[paraNode addChild:para4 z:3 parallaxRatio:CGPointMake(3, 0) positionOffset:downOffset];
"The CCParallaxNode is created like any other node, but its children are added using a special initializer. With it you specify the parallax ratio, which is a CGPoint used as a multiplier for any movement of the CCParallaxNode In this case, para1 would move at half the speed, para2 at the normal speed, para3 at double the speed of the CCParallaxNode, and so on"
So basically, its the ratio that the individual layers are moved in the relation to the movement of the whole CCParallaxNode.