I am developing an XNA project, where there are two DrawableGameComponents A and B, with the following constraints:
Either A is visible, or B is visible. So only one of their "Draw" methods has to be called.
Both A and B need to be enabled - always. So the "Update" method of each has to be called under all circumstances.
Currently both A and B are executed in the same thread. However, the "Update" methods of them are very CPU-Intensive. Since both GameComponents do not need to talk to each other, and both GameComponents do not need to share any data, it is easily possible to parallelize them.
What I would like to know is how to do that in XNA. The "Update" and "Draw" methods are called by the XNA Framework, so I do not know where to put the Threads. Is there a standard way of doing this?
Usually this is done through game state managment, where the Game1 class (default class) is used to call the Update() and/or Draw() of other classes (game components)
Take a look at the xnadevelopment game state managment tutorial, their they describe how to call diffrent updates and draws of different classes, and hopefully u'll see that multi-threading can be implemented in the Game1 class (default auto-created XNA class)
p.s. if you dont mind doing a lot of reading take a look at this article on XNA multi threading, its accompanied by some diagrams that explain how it works very well.
You haven't specified if you need both Update's to run simultaneously so I'm going off the assumption that one component is the only that needs to be drawn.
Using DrawableGameComponents they are automatically synced with your Game object, but, if you store a reference to each component instead of instantiating them without a stored reference, such as:
componentOne = new FirstComponenet(this);
Components.Add(componentOne);
componentTwo = new SecondComponent(this);
Components.Add(componentTwo);
// Immediately disable componetTwo
componentTwo.Enabled = false; // Prevents Update from firing
componentTwo.Visible = false; // Prevents Draw from firing (for Drawable components only)
Then you can let XNA manage the Update/Draw loops as per normal. componentOne and componentTwo being class level variables, you can manage when each are active.
Again, this is based on the assumption that you don't need one to update at the same time the other does.
Related
I want to understand some best practices regarding using MVVM and multithreading. Let us assume I have a ViewModel and it has an observableCollection. Also, let us assume I pass this collection to another service class which does some calculation and then udpates my collection.
After a point I realize that I want to make this a multithreaded call. When I make the call to the service class using threads or tasks what results is a cross thread operation. The reason is quite obvious because the service class updates the collection whcih in turn will update the UI on the background thread.
In such scenarios what is the best practice? Should we always write our service class in such a way that it first clones the input and then updates that cloned copy? Or should the view model always assuem that the service calls might be multithreaded and send a cloned copy?
What would be the recommended way to solve this?
Thanks
Jithu
A solution that might solve the cross-thread exception is by implementing the OnPropertyChanged in the base class of all ViewModels to switch to the correct thread/synchronization context so all properties in the View that are bound to the changing property will have their handlers called on the correct thread. See: Avoid calling BeginInvoke() from ViewModel objects in multi-threaded c# MVVM application
If/when you create copies you are postponing the synchronization and, in many cases, making it harder than need be.
A web service will always return new objects, how you, or a framework, updates the model using these object is up to you. A lot would depend on the amount of checks and updates coming in. There is no recommended way, see whatever fits the applications requirements.
I am new to JavaFX and i have been recently googling around for a while to understand this.
I am planning to rewrite an existing screen-manager framework in my project which is in Swing.
I am interested to understand what is the alternative to JComponent in FX ?
Is it Stage or window or Control or Parent, i am not able to conclude. Neither i am sure if there is such an alternative any.
Why do i need the alternative for JComponent ?
Well, in the screen-manager framework that i have in place, we always return the type for any individual swing component (say a panel) as JComponent. So i am eager to know the alternative in FX, if we have one.
Thanks in advance for any help.
Somewhat loosely, the equivalent to JComponent is Node
I say loosely, because they are different things and it isn't a 100% equivalence relation, but I guess you can think of them as roughly representing similar things. Nodes represent more stuff than JComponents because they can represent shapes, media views, etc.
JComponent is:
The base class for all Swing components except top-level containers. To use a component that inherits from JComponent, you must place the component in a containment hierarchy whose root is a top-level Swing container. Top-level Swing containers -- such as JFrame, JDialog, and JApplet -- are specialized components that provide a place for other Swing components to paint themselves.
And Node is:
Base class for scene graph nodes. A scene graph is a set of tree data structures where every item has zero or one parent, and each item is either a "leaf" with zero sub-items or a "branch" with zero or more sub-items.
Note that a Scene is contained within a Window (or Stage), so somewhat analogous to a JComponent, a window is not a Node (but pretty much everything else that JavaFX displays is).
See the Working with the Scene Graph tutorial from Oracle for more information on what Nodes are and how they are used.
Im currently working on an exercise, for which I want to create a technical design documentation.
Therefore, I need to evaluate possible solutions to a bunch of problems coming with my fictional project.
Here's a quick glance at the exercise:
The game's art & core game design are split up very harshly - basically, the core system, game mechanics and design are created to be very abstract, in order to allow them to work with a very wide variety of art settings. Also, one of the restrictions is to re-use as many assets, levels & designs as possible.
Now to my question:
I want the level designers to create levels using "template" objects (object which have all the technical features that are required, ie slots for attachments, correct scale, textures etc) and later replace these objects with set of assets I receive from my outsourcer.
Since I dont want to manually replace all objects whenever I get a new set of assets, this is what I wanted to do:
Each template object gets a descriptive label, and each asset delivered by the outsourcer needs to have the exact same label name as its corresponding template-counterpart stored in it as well (for example as a custom attribute, a channel, or simply in its name).
I now want to replace all templates with the related asset using a script.
This would be done for each set of assets. I would also keep several deployments of my engine, one per set, but initially, they'd all start out with the templates that need to be replaced (since there will need to be some modifications for each setting, both visually and from a game design perspective, keeping all assets in one trunk/project didn't make any sense to me).
To make this easier i'd use a "database" of some sorts (probably a simple dictionary which the engine script could query and which would be filled out beforehand by another script upon delivery of new assets?).
My question is: is this possible? If yes, how difficult would this be from a programmers perspective? I have only limited knowledge in this field, so I'd love to hear what you lads & ladies think about this.
Also (very important) - do you know of a better way to achieve this "replacability" of assets? Or simply have an easier way to achieve what I want to do? I appreciate any feedback! Thank you!
quick edit: This would not only be applied to 3d Objects; textures would also need to be replaced, obviously
I think you are looking for Prefabs.
Basically prefabs implements a sort of prototype pattern.
Instead of putting into scene's hierarchy directly a GameObject you can make it a prefab and put into the scene a GameObject that is an instance of that prefab.
When a GameObject into the scene is linked to a prefab, and the prefab will be modified, the linked object will be modified too.
If you have several instances of the same prefab, all istances will be updated as well.
The only strong limitation to this feature is that, since now, nested prefabs aren't supported.
I want the level designers to create levels using "template" objects
(object which have all the technical features that are required, ie
slots for attachments, correct scale, textures etc) and later replace
these objects with set of assets I receive from my outsourcer.
This is the tipical use case. You have a placeholder into the scene (es. a Cube) that will be subistitued by a model when the artists will provide it.
If you instantiate 100 cubes into the scene, when you need to substitute them, you would do it manually for all objects.
If instead you have created a prefab (lets call it ModelPrefab) and the cubes into the scene are instances of that prefab, when you'll have the new 3d model you can simply update the prefab and all linked instances will be updated too.
My question is: is this possible? If yes, how difficult would this be
from a programmers perspective?
If you can work without nested prefabs you have to do nothing, it's already implemented. If you need to implement nested prefabs, it might not be so straightforward.
quick edit: This would not only be applied to 3d Objects; textures
would also need to be replaced, obviously
I made the example above using the models, but you can make a prefab from each GameObject that is actually a collection of Components (have a look at Component Based Object Management if you are interested).
EDIT
Yes, it is possible to update prefabs throught script the required functions are in the UnityEditor namespace, so they mast be used through an editor extension.
You can found all you need in PrefabUtility class.
I have an application that I am working on, and I'm basically self-teaching GUI programming. I asked a fairly involved question over on programmers.stackexchange. This question is about the mechanics of an idea I had not tried.
I have three widgets: a TreeView, a TextField, and a DrawingArea. Each of the three widgets interacts very intimately with events on one necessarily triggering actions on the other. Those three widgets largely do not interact with the rest of the application except (so far) by reading an MVar containing the global application state.
Currently I can think of no case in which the larger application should ever interact directly with any of those three widgets. Further, that identical pattern would be replicated to review other data that has the same form. So, it seems to me that it would make sense to actually bind these three widgets together into a larger composite widget that can interact with GTK's normal event queue. So, for instance
type MyDataViewWidget = (TreeView, TextField, DrawingArea)
data DataUpdatedSignal a = DataUpdatedSignal a
data RedrawEvent a = RedrawEvent a
So, the widget would use DataUpdatedEvent to indicate to the rest of the application that something inside MyDataViewWidget changed, and RedrawEvent would tell the widget that it needs to redraw or re-read the source data.
(technically, I have not thought through semantically what the various actions in the composite widget would do... whether the widgets would just have a read-only copy of the application data and need to receive new read-only copies with the RedrawEvent or perhaps the widgets would have the MVar itself and be allowed to change the data in the MVar, etc... I'm just interested at the moment in how to actually do this)
Are there any examples of doing something like this? Basically, what instances do I need to implement to create the new widget and the two signals? I'd prefer to stick to Haskell, but I could drop to C in order to build up the new widget.
Unfortunately, there is currently no pure-Haskell way to (correctly) implement the Widget type class. You'll need to implement your widget in C, then import it via the FFI. There are numerous examples of this -- basically all of gtk+/gtk2hs is a collection of hundreds of examples of doing this.
I've been starting to get into game development; I've done some tutorials and read lots of articles but one thing I'm not sure about is what is the best way to manage large numbers of temporary objects, e.g. bullets.
Should each entity manage its own bullets, should I have a global bullet manager or should I create each bullet as a new full-blown individual object (that seems pretty inefficient though)?
Also, when using a component pattern what should I do about properties that seems generic, e.g. position, velocity, etc..?
Some stuff I've read seem to think that everything should be in some kind of component while others seem to think that generic properties that will be commonly accessed by a variety of components should be a member of the entity class itself.
Forgive me, these are probably simple but I want to make sure I'm thinking in the right direction.
Thank you very much!
Creating each bullet as a "fully blown object" shouldn't be too inefficient - have a look at the Object pool pattern, which outlines a way to speed up these object creations.
As for your question re: components and generic properties, it depends on how strictly you wish to follow the component architecture. If you want to be really strict with the component architecture, every property should be in a component and different components should talk to each other. Otherwise, for efficiency reasons, share some properties in the main object. For more information, have a look at this page on the component behavioural pattern.
The original Quake uses a fixed-size pool for entities (which are also sometimes called edicts). Anything whose existence persists between frames is an entity. This includes "shaped physical" things like the world and doors, rectangular physical things like monsters, players, and nails, movetype-transparent things like weapons, invisible but touchable rectangular things like trigger fields, and entirely-nonphysical things like delay events.
I think the limit in Quake is something like 700 edicts; the game will crash if the limit is exceeded. I think edicts are simply stored in an array, since every property which exists for any edict exists for all of them.