Let’s make a multiplayer game (part 8)

In the previous article we implemented smoothing of player movements on both the client and server side. In this article we will implement the functionality required to allow the player to fire shots.

As per the previous articles the first class to implement is the Shot class. This class will represent a bullet flying across the screen and inherits from the Sprite base class. The Shot class has two additional properties as shown below.

public long FiredById get; private set;

public bool FiredByPlayer get; private set;

The FiredById property is used to store the Id of the entity that fired the shot.

The FiredByPlayer property is used to indicate whether the player fired the shot. When we implement enemies this property will be false when an enemy ship fires at the player.

Shots are managed by the ShotManager class, meaning that the ShotManager is responsible for drawing all the shots and updating the movement of the shots. Shots are removed from the ShotManager when they move out of the screen bounds.

public Shot FireShot(Vector2 position, Vector2 velocity, long firedById, bool playerFired)

    Shot shot = this.FireShot(
        Interlocked.Increment(ref shotIdCounter), position, velocity * this.shotSpeed, firedById, playerFired);
    this.OnShotFired(shot);
    return shot;

The FireShot method is used to fire a shot and takes as input parameter the position from where the shot is fired and the velocity (direction and speed) of the shot. Additional meta data includes the Id of the entity that fired the shot and whether the firing entity is a player. The FireShot method raises an event that is handled by the Game class to notify the client or server (depending who is firing the shot) when a shot is fired.

Sending Messages

As per the previous articles we send messages by handling the events raised by the Manager type classes. In this case we handle the ShotFired event as follows.

this.soundManager = new SoundManager(randomNumberGenerator);
this.shotManager = new ShotManager(this.resolutionManager, this.soundManager);
this.shotManager.ShotFired += (sender, e) => this.networkManager.SendMessage(new ShotFiredMessage(e.Shot));

The ShotFired event is handled for both the client and the server.

The ShotFiredMessage is similar to the message classes defined previously.

public class ShotFiredMessage : IGameMessage

    #region Constructors and Destructors

    public ShotFiredMessage(NetIncomingMessage im)
    
        this.Decode(im);
    

    public ShotFiredMessage(Shot shot)
    
        this.Id = shot.Id;
        this.Position = shot.SimulationState.Position;
        this.Velocity = shot.SimulationState.Velocity;
        this.FiredByPlayer = shot.FiredByPlayer;
        this.MessageTime = NetTime.Now;
        this.FiredById = shot.FiredById;
    

    #endregion

    #region Public Properties

    public long FiredById get; set;

    public bool FiredByPlayer get; set;

    public long Id get; set;

    public double MessageTime get; set;

    public GameMessageTypes MessageType
    
        get
        
            return GameMessageTypes.ShotFired;
        
    

    public Vector2 Position get; set;

    public Vector2 Velocity get; set;

    #endregion

    #region Public Methods and Operators

    public void Decode(NetIncomingMessage im)
    
        this.Id = im.ReadInt64();
        this.MessageTime = im.ReadDouble();
        this.Position = im.ReadVector2();
        this.Velocity = im.ReadVector2();
        this.FiredByPlayer = im.ReadBoolean();
        this.FiredById = im.ReadInt64();
    

    public void Encode(NetOutgoingMessage om)
    
        om.Write(this.Id);
        om.Write(this.MessageTime);
        om.Write(this.Position);
        om.Write(this.Velocity);
        om.Write(this.FiredByPlayer);
        om.Write(this.FiredById);
    

    #endregion

The above ShotFiredMessage is very similar to the other GameMessages we have defined thus far. In this case we have made provision for the FiredById and FiredByPlayer properties.

Receiving Messages

The ShotFiredMessage is handled using the same pattern as the previous message types. The ProcessNetworkMessages method in the game code is updated as follows:

case NetIncomingMessageType.Data:
    var gameMessageType = (GameMessageTypes)im.ReadByte();
    switch (gameMessageType)
    
        case GameMessageTypes.UpdateAsteroidState:
            this.HandleUpdateAsteroidStateMessage(im);
            break;
        case GameMessageTypes.UpdatePlayerState:
            this.HandleUpdatePlayerStateMessage(im);
            break;
        case GameMessageTypes.ShotFired:
            this.HandleShotFiredMessage(im);
            break;
    

    break;

With the HandleShotFired method implemented as follows:

private void HandleShotFiredMessage(NetIncomingMessage im)

    var message = new ShotFiredMessage(im);

    var timeDelay = (float)(NetTime.Now – im.SenderConnection.GetLocalTime(message.MessageTime));

    Vector2 adjustedPosition = message.Position + (message.Velocity * timeDelay);

    this.shotManager.FireShot(
        message.Id, adjustedPosition, message.Velocity, message.FiredById, message.FiredByPlayer);

As before, we decode the game message into our ShotFiredMessage class. We calculate the time delay and update the position of the Shot taking into account any latency. We then call the FireShot message on the ShotManager class to add the shot to the collection of shots to be managed.

Note: We are using the non event raising override of the FireShot method. This pattern is repeated in all the manager implementations. On each manager we have a version of the method that will raise the “create” or “update” event and a version that will add the object instance but not raise any events. The latter version is used when processing game network messages to update the local state in our manager classes.

By adding a few lines of code to the PlayerManager class we now have the player ship firing bullets on both the client and server.

if (this.inputManager.IsKeyDown(Keys.Space))

    this.FireShot();

private void FireShot()

    if (this.shotTimer.Stopwatch(200))
    
        this.shotManager.FireShot(
            this.localPlayer.SimulationState.Position + this.gunOffset, new Vector2(0, -1), this.localPlayer.Id, true);
    

The Update method will check if the Spacebar is pressed and call the FireShot method. We have limited the shots to be fired to fire every 200ms. Shots are fired from the SimulatedState position taking into account a GunOffset to set the initial position of the shot.

The video below shows an example of shots being fired by the client player instance and how the shots are displayed on the server-side.

Firing shots (200ms delay)
find the cost of your paper

Sep 13, Grand Remembrances

Today is Grandparents Day in the United States. Being a Grand is a special honor. I feel very blessed that my wife and I have two grandchildren. We were able to visit them today. Yes, we are still being cautious with the coronavirus, but we also find it very difficult to not see them when they live so close. So today we did drop by to visit Jacob (age 10) and Sophia (age 7) along with their parents. We brought donuts and caught up with them. Our grandchildren are still pretty young and this is a precious time in their lives – and ours!

I wish I had known my grandparents better. We never lived in the same place. Dad was a career Air Force pilot, so we moved around a lot. But we did get to see them once in a while when they would visit us, or we them.

A Plague of Giants

There are five known magical ‘kennings’ or types: air, water, fire, earth, and plants. Each nation specializes in of these kennings, and the magic influences the society. There’s a big pitfall with this diversity of ability and locale–not everyone gets along.

Enter the Hathrim giants, or ‘lavaborn’ whose kenning is fire. Where they live the trees that fuel their fire are long gone, but the giants are definitely not welcome anywhere else. They’re big, they’re violent, and they’re ruthless. When a volcano erupts and they are forced to evacuate, they take the opportunity to relocate. They don’t care that it’s in a place where they aren’t wanted.

I first read Kevin Hearne’s Iron Druid books and loved them (also the quirky The Tales of Pell), so was curious about this new venture, starting with A PLAGUE OF GIANTS. Think Avatar: The Last Airbender meets Jim Butcher’s Codex Alera series. Elemental magic, a variety of races, different lands. And it’s all thrown at you from page one.

But this story is told a little differently. It starts at the end of the war, after a difficult victory, and a bard with earth kenning uses his magic to re-tell the story of the war to a city of refugees. And it’s this movement back and forth in time and between key players in this war that we get a singularly grand view of the war as a whole. Hearne uses this method to great effect.

There are so many interesting characters in this book that I can’t cover them all here. Often in books like this such a large cast of ‘main’ character can make the storytelling suffer, especially since they don’t have a lot of interaction with each other for the first 3/4 of the book–but it doesn’t suffer, thankfully. And the characterization is good enough, despite these short bursts, that by the end we understand these people and care about what happens to them.

If there were a main character it would be Dervan, a historian who is assigned to record (also spy on?) the bard’s stories. He finds himself caught up in machinations he feels unfit to survive. Fintan is the bard from another country, who at first is rather mysterious and his true personality is hidden by the stories he tells; it takes a while to understand him. Gorin Mogen is the leader of the Hathrim giants who decide to find a new land to settle. He’s hard to like, but as far as villains go, you understand his motivations and he can be even a little convincing. There’s Abhi, the son of hunters, who decides hunting isn’t the life for him–and unexpectedly finds himself on a quest for the sixth kenning. And Gondel Vedd, a scholar of linguistics who finds himself tasked with finding a way to communicate with a race of giants never seen before (definitely not Hathrim) and stumbles onto a mystery no one could have guessed: there may be a seventh kenning.

There are other characters, but what makes them all interesting is that they’re regular people (well, maybe not Gorin Mogen or the viceroy–he’s a piece of work) who become heroes in their own little ways, whether it’s the teenage girl who isn’t afraid to share vital information, to the scholars who suddenly find how crucial their minds are to the survival of a nation, to the humble public servants who find bravery when they need it most. This is a story of loss, love, redemption, courage, unity, and overcoming despair to not give up. All very human experiences by simple people who do extraordinary things.

Hearne’s worldbuilding is engaging. He doesn’t bottle feed you, at first it feels like drinking from a hydrant, but then you settle in and pick up things along the way. Then he shows you stuff with a punch to the gut. This is no fluffy world with simple magic without price. All the magic has a price, and more often than not it leads you straight to death’s door. For most people just the seeking of the magic will kill you. I particularly enjoyed the scenes with Ahbi and his discovery of the sixth kenning and everything associated with it. But giants? I mean, really? It isn’t bad enough fighting people who can control fire that you have to add that they’re twice the size of normal people? For Hearne if it’s war, the stakes are pretty high, and it gets ugly.

The benefit of the storytelling style is that the book, despite its length, moves along steadily (Hearne is no novice, here). The bits of story lead you along without annoying cliffhangers (mostly), and I never got bored with the switch between characters. It was easy to move between them, and they were recognizable enough that I got lost or confused. The end of the novel felt a little abrupt, but I guess that has more to do with I was ready for the story to continue, despite the exiting climax.

If you’re looking for epic fantasy with fun storytelling and clever worldbuilding, check out A PLAGUE OF GIANTS.

The post A Plague of Giants appeared first on Elitist Book Reviews.

The Artwork Of Gary Choo

Gary Choo is a concept artist/illustrator based in Singapore. I’ve know Gary for a good many years ( 17, actually ), working together in animation studios in Singapore like Silicon Illusions and Lucasfilm. Gary currently runs an art team at Mighty Bear Games, but when time allows he also draws covers for Marvel comics, and they’re amazing –

The Art Of Gary Choo
The Art Of Gary Choo
The Art Of Gary Choo
The Art Of Gary Choo
The Art Of Gary Choo

To see more of Gary’s work or to engage him for freelance work, head down to his ArtStation.

The post The Art Of Gary Choo appeared first on Halcyon Realms – Art Book Reviews – Anime, Manga, Film, Photography.

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