Month completed. I am content

Lets continue with the coop stuff! I want to finish it and then continue with my personal dungeon project. Lets look into the claude chat first, where I asked if synchronizer and spawner are maybe not the best methods.

Enet vs Godots High-Level Multiplayer Stack

ENet

The actual protocol handling packets, reliability and ordering

Godots High-Level implementation

MultiplayerSynchronizer - syncs node properties across the network
MutliplayerSpawner - spawns nodes over the network

ENet is battle tested, most of the critique is about the High-Level implentation and it’s lack of control like missing client-side prediction and lag compensation. Another issue are security concerns, as the high-level API can be bypassed. Server-side verification can help, but godot does not force you to implement these.

Example for an insecure way:

@onready var synchronizer = $MultiplayerSynchronizer
# Client sends this, server just accepts it blindly
var player_health = 100
var gold = 999

Players can change these values locally an it just replicates to every other client.

Secure way:

# On the server
@rpc_unreliable(call_local)
func take_damage(amount: int):
    if not is_multiplayer_authority():
        return  # Only server runs this
    
    health -= amount
    if health < 0:
        die()
    # Sync broadcasts the new health

The server has to never trust client-sent values and needs to validate them. Start with using is_multiplayer_authority() and build own validation logic on top of it.

I guess this wont be an issue for coop games, but if leaderboards are involved, this needs to be tackled, as this is a pvp mechanic. Same for global progression.

In the tutorial we used ENet already, but just to allow godot to use it as a transport layer. Without these we would:

Need to manually create sockets
Handle lost packets (like in TCP)
Handle packet ordering
Handle disconnecting and connecting
… Basically you would need to implement the whole network protocol. Seems interesting but lets get going with the fun stuff (the gameloop and the project) first.

Weapon Rotation & Player Flipping

When flipping just setting the Flip H propertie seems like the correct apporach. But if the node is not centered it could be off center. Also Animations can have a problem with it later.

So what is an interesting solution?

To invert the x axis scale.

Animated Background (shader)

Add an image to an sprite2d and enable region

Which extends the sprite, but does not tile it:

To fix this, change the texture repeat property from Inherit to Enabled.

Which then shows:

Now lets add movement with a shader! Create a new ShaderMaterial

Create a new shader

After saving the file, click on the newly created shader:

This should open the gdshader file:

Simple shader to move the background at a constant speed.

shader_type canvas_item;

void fragment() {
	// Called for every pixel the material is visible on.
	vec4 color = texture(TEXTURE, UV + vec2(.14 * TIME, .06 * TIME)); // 4 procent to x, 2 to y
	//vec4 color = vec4(1.0); // shorthand for 4 values that are 1 for all RGBA values like vec4(1.0, 1.0, 1.0, 1.0)
	COLOR = color;
}

Also, to load this background you need to create an autoload. YES, scenes can also be autoloaded.

Create a scene out of this branch, add it in autoloads, reposition it inside the scene and this should work.

Credit: Firebelley Games (Coop Tutorial, check it out!)