got a CClayer with many b2bodies and fixtures etc.
all b2_body objects are allowsleeping set to true. but they never sleeps.
notes:
all b2_body ‘s :setAwake are TRUE at initial creation.
all b2_body ‘s :setActive are TRUE at initial creation.
all fixture.friction is 0.001 or 0. no difference
got a custom simple Contact Listener class...
when I check the velocity via
b2Vec2 velocity = b->GetLinearVelocity();
velocity.Length();
is zero. but somehow b->IsAwake() is always YES.
it seems some of bodies are jiggling back and forth infititely with a very little bit velocities.
yes they are stacked.
what may be the reason ?or is there a method to fix this problemma ?
should I stop linear velocities of contact bodies in my custom contactClass ?or...
thank you.
Related
I have a table basically in every row i have get function that makes a backend request with store service. But somehow when there is one row it works expect, but when there is multiple rows it always try to recalculate get function which makes sending infinite request to backend. I am using glimmer component
I cannot use model relation on ember side at this point, there is deep chain on backend side. Thats why i am making backend request.
get <function_name>() {
return this.store.query('<desired_model_name>', { <dependent1_id>: <dependent1_id_from_args>, <dependent2_id>: <dependent2_id_from_args> });
}
I fixed this problem with using constructor. But do you have any idea why this get function re-calculate all the time? Dependent_ids are constant.
Weird thing is when results are [] empty array it does not re calculate every time. Even the query results are same it still try to recalculate every time and making infinite request to backend.
But do you have any idea why this get function re-calculate all the time?
When something like this happens, it's because you're reading #tracked data that is changed later (maybe when the query finishes).
because getters are re-ran every access, you'll want to throw #cached on top of it,
// cached is available in ember-source 4.1+
// or as early as 3.13 via polyfill:
// https://github.com/ember-polyfills/ember-cached-decorator-polyfill
import { cached } from '#glimmer/tracking';
// ...
#cached
get <function_name>() {
return this.store.query(/* ... */);
}
this ensures a stable object reference on the getter that the body of the getter only re-evaluates if tracked data accessed within the getter is changed.
Weird thing is when results are [] empty array it does not re calculate every time. Even the query results are same it still try to recalculate every time and making infinite request to backend.
Given this observation, it's possible that when query finishes, that it's changing tracked data that it, itself is consuming during initial render -- in which case, you'd still have an infinite loop, even with #cached (because tracked-data is changing that was accessed during render).
To get around that is fairly hard in a getter.
Using a constructor is an ok solution for getting your initial data, but it means you opt out of reactive updates with your query (if you need those, like if the query changes or anything).
If you're using ember-source 3.25+ and you're wanting something a little easier to work with, maybe ember-data-resourecs suits your needs
the above code would be:
import { query } from 'ember-data-resources';
// ...
// in the class body
data = query(this, 'model name', () => ({ query stuff }));
docs here
This builds off some primitives from ember-resources which implement the Resource pattern, which will be making a strong appearance in the next edition of Ember.
I am simply trying to deactivate a constraint in textViewDidBeginEditing and the deactivate in textViewDidEndEditing.
My NSLayoutConstraint is an outlet. The deactivation in textViewDidBeginEditing works, but then the reactivation on textViewDidEndEditing finds nil for the constraint.
I have tried this with both the .isActive instance value as well as the NSLayoutConstraint.activate/deactivate functions.
The Answer
I played around with Vasil Hristov's answer and that didn't work because he simply suggested 0 and 1000. From Documentation:
Priorities may not change from nonrequired to required, or from required to nonrequired. An exception will be thrown if a priority of NSLayoutPriorityRequired in OS X or UILayoutPriorityRequired in iOS is changed to a lower priority, or if a lower priority is changed to a required priority after the constraints is added to a view. Changing from one optional priority to another optional priority is allowed even after the constraint is installed on a view.
So, I had to change my priority in IB first to be something else (I chose 750 - High) and then just switched it to 250 when it wasn't needed, and created a second constraint conflicting with the first that had a 500 priority(do something else) at all times, which got me the behavior I wanted.
According to the above documentation, since High is not required, I should have been able to switch to 0, but that was still resulting in crashes so I must be reading that wrong. Hence, why I did the second constraint thing.
You can try to change the priority of constraint.
For example:
constraint.priority = 0; // it's turn off
constraint.priority = 1000; // it's turn on
I am trying to think through how to implement a countdown on a stamina level. For example, maximum 100% and over time it decreases. I don't need to know how to display it but the technology behind it to get it working and where to look.
This countdown would keep on going down when the application is closed.
I was looking at NSUserDefaults as a means to do this. Is this correct?
Similar to the top bar as shown below:
You can save latest refueled stamina value in NSUserDefaults or in iCloud and calculate current value using something like this:
timePassedInSeconds = currentTime - latestMaxValueSaveTime;
newStamina = latestMaxValue - (timePassedInSeconds * decreasePerSecond);
This way each time the player refuels stamina (e.g. buys some food for animal) you reset stamina to 100% (or add some percentage depending on food type) and save this value into latestMaxValue and save the time it was refueled into latestMaxValueSaveTime (you can store both in NSUserDefaults)
And you calculate newStamina in update: of the scene or in onEnter: method of the scene if it needs to be calculated once.
This way it will decrease even when the app is closed.
However, if you want to avoid players resetting stamina by changing device time you should get time from the server (preferably in UTC, to avoid issues with timezones and daylight saving).
Having 2 computed properties based on the same dependency only one computed property runs. The docs says that it is cached what about a situation when I'd like to have the following:
foo: (->
console.log 'foo'
).property('dependency')
bar: (->
console.log 'bar'
).property('dependency')
Now the bar isn't called and I have to resort to observer. Can I make it work?
Edit
The question is about computed properties but it wasn't reflected in the example code - instead of property I used observes. It is now changed. Sorry for confusion.
Edit#2
I modified the great example by #MilkyWayJoe so that it now looks like my solution. Unfortunately (or fortunately) it works, but my solution didn't. Here's the gist what I was after:
With the help of a slider I could set a balance value to be transferred to another credit card provider. Let's say that the value is transferValue. Whenever it changed I had to calculate the annual interest to which the transfer fee was added.
So for example let's say that in my current credit card I have $1000 and the annual interest rate is 19%. It's way too much so I look for another, cheaper solution. It turns out that Bank X offers Balance Transfer Credit Card Y which interest rate is 10% + 3.5% transfer fee.
OK. So I set $1000 on the slider and here goes the magic. I want to calculate interest rate and transfer fee whenever the value changes.
In the modified example it works: http://jsfiddle.net/gqSMU/2/
but failed to do so in my first solution. It was kind of this one:
cardInterest: (->
apr = #get 'purchaseRate'
amount = #get 'transferValue'
#get('calculatedTransferFee') + #calculateInterest apr, amount
).property('transferValue', 'calculatedTransferFee')
As you can see it accesses calculatedTransferFee. The problem was that the value wasn't recalculated. I'm not sure it is worth of mentioning but in the first solution only cardInterest was requested by Handlebars template.
And this is my current solution with observer:
calculatedTransferFee: 0
transferValueDidChange: (->
if #get('isCurrentCardChosen')
transferFee = parseFloat #get('balanceTransferRate') / 100
transferValue = #get 'transferValue'
calculatedTransferFee = if isNaN(transferFee) then 0 else transferFee * transferValue
#set 'calculatedTransferFee', calculatedTransferFee
).observes('transferValue')
It isn't a nice solution, is it? That's why I thought it may be a better solution than to resort to an observer.
I hope that now it is clearer. I'd be grateful for any further feedback!
Not quite sure if I understand what you're trying to achieve since you're talking about property but your code is using observes (I realize this is a conceptual sample code, just not sure where you're going).
Usually, property will be a "reactive accessor" to a value, and 99.9% of the time you want it to be cached (it is by default, unless you say .property('whatever').volatile()), while observe will fire a function when whatever property it is watching changes. If you just want to have two properties firing for the same dependency you could:
App.SomeModel = Em.Object.extend({
someDependency: true,
foo: function() {
// all that's in here will fire only once when 'dependency' changes, and store
// the returning value in cache, and every time something reads this property,
// it will retrieve the cached value.
// A way to test this, is to run the following from your View:
// "alert(this.controller.get('content.foo'));"
// It will alert the string but will not log "whatever bro" again.
console.log('whatever bro');
return "this.foo %# a dependency".fmt(this.get('someDependency') ? "has" : "doesn't have");
}.property('someDependency'),
bar: function() {
// same as above
console.log('whatever dude');
return "this.bar %# a dependency".fmt(this.get('someDependency') ? "has" : "doesn't have");
}.property('someDependency'),
nope: function() {
// same as above, except this is volatile
// and will fire the console.log every time
console.log('y\'all need science');
return "this.nope %# a dependency".fmt(this.get('someDependency') ? "has" : "doesn't have");
}.property('someDependency').volatile()
});
(see fiddle)
If you need it to be logged everytime (perhaps for debugging or whatever reason), you could use volatile or observes.
If I'm tripping and this's not what you want, perhaps you could rephrase your question or refresh the sample code to something closer to your real-life scenario to clarify what's being asked.
I have a sequence that I am trying to repeat, and change the delay time with each occurance of the repeat... Something like:
__block CCDelayTime *delayTime = [CCDelayTime actionWithDuration:myDelay];
[CCRepeat actionWithAction:[CCSequence actions:
[CCCallFunc actionWithTarget:self selector:#selector(doSomething)],
delayTime,
[CCCallBlock actionWithBlock:^{
delayTime.duration = delayTime.duration / 2
}....
I am getting no where real fast.. Depsite the fact that the instance of CCDelayTime's duration_ ivar is in fact properly getting set to half of its previous value, when stepping through the code, it appears that as soon as control reaches one of the base class' (CCActionInterval) methods such as step or update:, the duration_ ivar is back to the original value (what myDelay was set to).
I spent quite a bit of time going through the cocos code trying to figure out why this is happening but eventually decided to give up and see if anyone here can help me. Perhaps there is a better way to do what I am trying to do in the first place?
what you do here is: call a function, wait for some time (delay), run a block that changes the waiting time of the action that already ran.
What you need to use is CCSpeed, add the delay action to it, and keep a reference to CCSpeed so that you can modify the speed from outside the sequence.