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Optimization using Servers

Engines like Godot provide increased ease of use thanks to their high level constructs and features. Most of them are accessed and used via the Scene System. Using nodes and resources simplifies project organization and asset management in complex games.

There are, of course, always drawbacks:

  • There is an extra layer of complexity.

  • Performance is lower than when using simple APIs directly.

  • It is not possible to use multiple threads to control them.

  • More memory is needed.

In many cases, this is not really a problem (Godot is very optimized, and most operations are handled with signals, so no polling is required). Still, sometimes it can be. For example, dealing with tens of thousands of instances for something that needs to be processed every frame can be a bottleneck.

This type of situation makes programmers regret they are using a game engine and wish they could go back to a more handcrafted, low level implementation of game code.

Still, Godot is designed to work around this problem.

See also

You can see how using low-level servers works in action using the Bullet Shower demo project

Servers

One of the most interesting design decisions for Godot is the fact that the whole scene system is optional. While it is not currently possible to compile it out, it can be completely bypassed.

At the core, Godot uses the concept of Servers. They are very low-level APIs to control rendering, physics, sound, etc. The scene system is built on top of them and uses them directly. The most common servers are:

Explore their APIs and you will realize that all the functions provided are low-level implementations of everything Godot allows you to do.

RIDs

The key to using servers is understanding Resource ID (RID) objects. These are opaque handles to the server implementation. They are allocated and freed manually. Almost every function in the servers requires RIDs to access the actual resource.

Most Godot nodes and resources contain these RIDs from the servers internally, and they can be obtained with different functions. In fact, anything that inherits Resource can be directly casted to an RID. Not all resources contain an RID, though: in such cases, the RID will be empty. The resource can then be passed to server APIs as an RID.

Warning

Resources are reference-counted (see RefCounted), and references to a resource's RID are not counted when determining whether the resource is still in use. Make sure to keep a reference to the resource outside the server, or else both it and its RID will be erased.

For nodes, there are many functions available:

Try exploring the nodes and resources you are familiar with and find the functions to obtain the server RIDs.

It is not advised to control RIDs from objects that already have a node associated. Instead, server functions should always be used for creating and controlling new ones and interacting with the existing ones.

Creating a sprite

This is an example of how to create a sprite from code and move it using the low-level CanvasItem API.

extends Node2D


# RenderingServer expects references to be kept around.
var texture


func _ready():
    # Create a canvas item, child of this node.
    var ci_rid = RenderingServer.canvas_item_create()
    # Make this node the parent.
    RenderingServer.canvas_item_set_parent(ci_rid, get_canvas_item())
    # Draw a texture on it.
    # Remember, keep this reference.
    texture = load("res://my_texture.png")
    # Add it, centered.
    RenderingServer.canvas_item_add_texture_rect(ci_rid, Rect2(texture.get_size() / 2, texture.get_size()), texture)
    # Add the item, rotated 45 degrees and translated.
    var xform = Transform2D().rotated(deg_to_rad(45)).translated