I am currently trying to simulate a solar system in unreal engine using blueprints. In order to calculate the force with which the actor (eg moon) should move, I need to know the mass of the parent actor (eg earth).
I am having issues trying to achieve this though, since I am quite new to Unreal. When I run my script, I am getting an error:
Blueprint Runtime Error: "Accessed None trying to read Class from property CallFunc_GetObjectClass_ReturnValue"
with a reference to Set ParentMass
which has to do with the following BP setup:
I am pretty sure this is happening because I am trying to retreive the mass of the parent but im doing it the wrong way.
Could anyone help me with retreiving the 'mass' value of the parent object?
Thanks!
What you're looking for is just the object reference to the parent planet, not it's class.
In your moon blueprint, make a variable called ParentPlanet of type BP_Earth object reference (or whatever the name of your earth BP is).
Click the eyeball beside the new variable to make it instance editable
Back in the main viewport, click on your moon in the world outliner. You should now see an option in the details panel to select the parent planet.
In BP_Moon, on begin play you can now get the parent reference, get it's mesh component, and use the node GetMass to find the mass of the mesh.
Related
I have 2 different types components. They both only use and contain an HTML5-canvas element, but need to show different types of data on a chart:
Component A (Only ever 1 of these)
Component B (0 to 4 of these)
Both components need the dateTime of the first data-entry from the two data-sets, but the dateTime of the last entry comes from their own respective data-sets.
Component A needs its first entry date from Component B.
Currently I do it like this:
Component B has the method that finds the date-limits from its own dataset. Using an Observer-pattern & Subjects, I broadcasts the returned dates through a service and into Component A.
The problem with this though, is that coupling suddenly becomes pretty tight. I can't initialize component A first, because it needs B to do its calculation first. Both components ideally should initialize and show/share their data simultaneously, and continue to do so. (E.g. If a user scrolls in one chart it should scroll all other components too, and so on.)
This is why I wanted an extra layer added on top of these components. A controller if you will.
I can't figure out what's best though:
A shared service that can take external data as input?
A container component? (Transclusion)
Another component, Component C, that A & B are children of?
As I'm still new to Angular 2, it's hard to tell which approach is best for future maintenance/development?
I'm being drawn towards creating another normal component as a parent, and have this component send and receive data to/from its children (A & B) as necessary.
I'm also uncertain as to what's "best practice" and if you can just use a component like an empty 'logic shell'. I've tried reading here and there, and I've found a lot, but I can't seem to get an exact answer to my question. It'll take time before I can comprehend all this knowledge and answer it myself, so I'm hoping someone could give me a helping nudge, thanks.
PS: I should add that my angular application will be a child-component in larger application, and will get its data from some other parent comp.
Why don't you put your logic into services?
You can also set up service hierarchies by injecting sub-services into a parent service.
If your logic is not UI / interaction related, you should put it into reusable services. If your logic is UI related, you could set up a parent component acting as a mediator between A and B (acting on their respective input/output parameters)
Whatever you do, it is a good idea to keep concerns separate.
Both A and B should not need to care about other components needing their output. Angular has Input/Output parameters for that.
Don't put some generic datetime calculation stuff into components. Make it reusable through services.
Keep coupling loose by introducing interfaces and injections.
Update:
Services should only use injectable constructor parameters, so you should pass your input using methods (or setters, but that is less expressive).
To pass arbitrary JSON objects, you could utilize any parameters. However if your json follows a certain structure, you could define an interface.
public doStuff(input: any): any { }
or
interface IMyDataContract {
dateField: string;
}
public doStuff(input: IMyDataContract): any { }
I'm new to om.next (and to clojurescript), and I have the following question. I can only get the root component to be invoked with the reconciler (i.e. have its query method invoked); every other component seems to need to be invoked with props and with om/factory. I think I'm missing something.
I am attempting to create a todo list app (100 points for originality!), with a filter to show completed/incomplete/all items. If my TodoList component is the root component, I can invoke it with query: [:todos] with no problem. I'd like to have a different root component, and also have a Filter component that goes through the reconciler.
Possible options I can see:
have multiple om/add-root! calls (this prevents us from having nested components that use the reconciler, and is not the pattern that I see in tutorials)
wrap everything in a global component and pass state down through props. But the examples make read a multimethod, which doesn't jive with this approach.
Is this possible? Thank you!
If you haven't already please take a look at Components, Identity & Normalization · omcljs/om Wiki · GitHub. This tutorial shows how to organize a multi-component application under a single root - and it should also make clear how read, mutate, Ident, IQuery, etc. are being used by each individual component to coordinate interaction with the one-and-only app state via the reconciler. The app-state is basically the application's database - using nested data structures inside a single Map.
React applications typically only have a single root component - if there are multiple roots they are typically organized by routes, i.e. one root per route (see also Top-level React Components — Medium).
Also: Om/Next: The Reconciler — Medium
The concept behind Om Next (and others such as reframe) is that there is one source of truth - your app state. With Om Next the UI of your application is made up of one (upside down) component tree. During rendering your app state is loaded into your Root component by Om Next interpreting its static query. This app state is received as 'props'. It is your job to pick these props apart and hand 'sub props' down the rest of the tree. You do this in the render method of each of your components.
So your second option is the way to go. reads are related to keywords that are in your static component queries. If you make sure that your state is in default db format, then in fact every read can be implemented the same way, making use of db->tree. Having a global component and making every read a multimethod are unrelated concepts, and thus not incompatible. In fact having both is quite idiomatic.
There are ToDo application examples already that you may wish to look at for reference: here and here.
One thing to note is that your Root component query will use joins to include the other components, so your query [:todos] does not look right to me. Something like [{:todos (om/get-query TodoList)}] would be better :-)
I'm creating a simple game to learn Flash programming. To have a clean model/view separation, I want to create a Player class which simply holds data relevant to the user. I'm also creating a StatusView class which extends MovieClip and which coresponds to a movie clip symbol which I've created in my Flash project. Basically the StatusView will display the data of my Player class onscreen.
I'm used to doing this sort of thing using listeners, so I've found the EventDispatcher class and added one as a member of my Player class. I'd like to have my StatusView movie clip add an event listener to my Player class so that it can receive messages whenever I change the data in my Player class.
The problem is, there doesn't seem to be anywhere for me to put my Player class so that the StatusView can find it (to add the listener). Everything in the project is created directly by one of the movie clips, and the runtime seems to create these movie clips in an arbitrary order. For example, say I create a MovieClip symbol called GameView and I create the instance of the Player there, and GameView is the parent of StatusView. When StatusView is constructed, I'd like to be able to access the Player from it's parent, but at that point GameView hasn't had it's constructor code run yet. This is true even if I wait for the ADDED_TO_STAGE event.
I could put the game model code in a singleton, but this seems like a hack to me. Is there a best practices way in Flash that lets me create and access my game model independent of all the MovieClip symbol stuff?
If you want to pass the reference of the Model to the constructor of the View, but are not calling the constructor yourself (because you do not create the object via code) you are out of luck here.
You could instead simply define a method on your View to pass a reference of the Model object:
public function setModel(value:Model):void
usage:
view.setModel(player);
There's no "law" that you have to pass the Model to the constructor of the View.
You can also create a set function for convenience:
public function set model(value:Model):void
usage:
view.model = player;
I feel like I have to disagree on the Singleton. The purpose of a Singleton is to guarantee that there's only one instance of it in existence. That's it.
It is not there to pass reference around easily (because the method to get the single instance is static). This is (IMO) a bad practice.
You could make anythign static in order to pass it around "easily". But this would make a mess and nobody does that.
But suddenly, just because the singleton pattern uses a static method, a lot of people think it's a clever way to get to the reference. I beg to differ.
First of all, you could implement Player class as singleton if you need just one instance. I don't think that that looks like a hack (for example, in PureMVC framework each model is a singleton).
At second, you can create instances of Player class in some general class (manager) and send them to views.
P.S. Also, I want to note that you can extend your Player class from EventDisptacher without creating specific field "eventDispatcher" in Player class. I don't know what way is better, but this one is simpler, imho.
I've made a resource dictionayry for a user control and create a class that derived from ResourceDictionary that managed different eventsetters and handlers for controls contained in the resource dictionary. So far so good, everything is working fine. My problem is to access members contained in my ResourceDictionary class from the user control. How to access a property in ResouceDictionary object from the user control?
Thanks a lot!
Ben
I finally find a way to handle it. I create a variable of my resourcedictionary type that handle also his events. After, I set the resource dictionary to the control by code with my variable. So now, I can handle events declared in my resource dictionary.
If someone need to see codes needed to get the job done, let me know.
I'm working on a portfolio suggestion application in Flash, which consists of two views: ask user for 3 to 4 points of information, and display recommendations based on that information.
The first view is going swimmingly, as all I need are the graphics to be created. However, I'm having trouble understanding how a AS3 variable can be seen across keyframes when it was declared and initialized on the first frame.
The only multi-view app I've done is a Restaurant Guide flash app that was described in Adobe Flash CS5 Classroom in a Book. In that example, the only AS function on four of the views
was a stop() function.
If I were to do the same in this app, and declare the variables as global in the first frame, will they be accessible throughout?
CLARIFICATION
Two comments have said that my question is unclear, so I hope this makes my question more understandable. I want to know how, if I gather all the user information on Frame 1 and then switch to a view on Frame 15, to access those variables on Frame 1.
This isn't really the way you're supposed to work in AS3. Each view should be an object in your library with an associated class. Your document should also have a class associated with it, and it is here that you would hold your common data. The document class would instantiate each view as it is required and pass in the relevant variables.
That said, if you want to work the old way you shouldn't have trouble declaring a variable on frame 1 like this:
var myVar:String = "Hello!";
and then accessing it on frame 15 of the same timeline like this:
trace(myVar);
If that's what you're doing and it's not working then you'll need to update your question with some code examples.