I'm new to iOS programming and I made a little game.
I have some sprites in the background of my scene which I want to move slowly from left to right.
Right now I'm doing this in the MainScene:
[self performSelectorInBackground:#selector(doBackgroundAnimation:) withObject:sprite];
and the method in which the animation takes place looks like this:
-(void)doBackgroundAnimation:(CCNode *)sprite {
while (//sprite is still in the scene) {
//move sprite a little bit right
}
}
This solution is not really what I was looking for, since the time it takes to run through the while-loop varies from device to device.
Is there a way to make sure that the animation takes an exact amount of time e.g. 5 seconds?
Something like:
performSelectorInBackground:#selector(doBackgroundAnimation:) withObject:turtle inTime:5.0
Thank you for your help!
It's been a while since I did game stuff but you have to adjust the distance you move the sprite according to the time since the last update of the screen. So you have a var called speed that you * by the time since the last refresh and then move the sprite that distance.
There are methods in sprite kit that deal with this. There are lots of tutorials on YouTube that cover this.
Related
I'm building a Mega Man clone for a school project and I just finished the code to make my character jump and it works perfectly. But I need it to display the actual jump sprite of Mega Man. This is the whole code in Game1:
http://pastebin.com/py7Y7mtD
The AnimatedSprites jt helps you decide the direcrtion and display the sprite. Doesn't matter right now if it's efficient. It's just for starts. When I'll get to more complex stuff I'll work on it.
MegamanJump has the jump sprite(5 or 6 sprites displayed from left to right)
MegamanJump_Flip is the same thing but to the left(again, forget about efficiency).
Basically you want to switch out the current drawable sprite with the sprite you want to draw depending on moving direction or moving direction + jump.
Since you already have a running update method, all you have to do is write another method that does this for you, a state variable to track what is happening and the actual states it can have, preferrably in an enum for clarity.
Essentially
private void swapSprite() {
if(state == CharacterState.LEFT) {
sprite = leftDrawable;
}
//etc other single ifs
if(state == CharacterState.LEFTJUMPING) {
sprite = leftJumpDrawable;
}
}
Change the states on button press combinations, call this method after checking for movement.
I hope this helped!
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.
Background
I'm making an iOS app for kids where you can use your finger to drag balls around on a screen.
I'm using Chipmunk 7.0.0 for the physics simulation.
I've adapted the Chipmunk demo code to implement the dragging functionality.
I'm using 2 ms fixed time step. (It's not like my app has anything better to do...)
Issue
I've recently added code to play a sound whenever the balls collide with each other or with a wall, which I'm doing inside a postSolve callback:
static void postSolve(cpArbiter *arb, cpSpace *space, cpDataPointer userData)
{
GameLayer *layer = (__bridge GameLayer *)userData;
[layer collisionHandler:arb];
}
-(void) collisionHandler:(cpArbiter*)arb
{
if(cpArbiterIsFirstContact(arb)) {
[[SimpleAudioEngine sharedEngine] playEffect:kCollisionEffectFilename];
}
}
Here's the problem... When I drag a ball into a wall, it generates a very large number of collisions, even when filtering on cpArbiterIsFirstContact, and it sounds terrible. It appears that the ball is bouncing off the wall, being driven back into wall by the constraint, rinse, and repeat. I'd like to play the collision sound only once or twice in this scenario.
Things I've tried that don't seem to work...
Filtering using cpArbiterTotalKE, cpArbiterTotalImpulse, or relative velocity: Impulse, kinetic energy, and relative velocity are all in the range of typical collisions.
Using a separate callback: The ball really is bouncing off the wall multiple times.
Reducing the step size: The physics engine actually takes longer to converge.
Rate limiting the sound effects: Better, but the ball still makes noise even after it looks like it's stationary.
Question
Is there a way to filter collisions for trapped bodies?
A simple and effective solution is to avoid playing the sound in quick succession.
When the ball contacts with the wall, check if the ball's "last contact" timer is lower than the current time. If so, play the sound and set the ball's "last contact" time to the current time plus x, where x is the timeout duration the sound shouldn't play again (ie 0.5 seconds).
In cocos2d-iphone you can add up an update method's deltaTime to keep track of time. There are also a number of ways to get system time, for example [NSDate date].timeIntervalSince1970 gives you the current number of seconds since 1970. I know, seems ridiculous, but if you get that number again sometime later, and subtract the previous number of seconds you get the difference in seconds, that's all that counts.
So you are using a constraint to drag the ball around, and the ball is elastic correct? Have you tried tweaking the constraint parameters at all? If the constraint has a lower maxForce, the chance for oscillations would drop significantly.
Another thing that can help is to increase the space's collision slop (how much shapes are allowed to overlap). The default value is 0.1 (in whatever scale you are using), but increasing it to a pixel or so can help this sort of thing significantly without being very visible.
I try create game use parallax scroll, I put sprites in the screen and after it the same sprites again, when first sprite go out of the screen I move it to the end of the sprite that in the screen. one of my sprites is a sun, I want show him once in minute. what is the better way to implement the parallax scrolling with the sun? when the sun go out of the screen place him before the screen with distance or use timer or something?
I would advise to use a timer. It's not too much of a hassle, so I would not say this is premature optimization. You will avoid the (really low) overhead of having a sprite moving outside the screen when there is no need to do so.
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.