Resources

A resource is global state attached to the world, not to any entity. Delta time. The input snapshot for this frame. The list of loaded materials. The active camera. Each resource type exists exactly once in the world and lives on world.resources.

Systems read and write resources directly. There are no accessor functions, no per-resource fan-out. The freecs macro generates the Resources struct from the declaration block and gives every field public access.

#![allow(unused)]
fn main() {
fn run_systems(&mut self, world: &mut World) {
    let dt = world.resources.window.timing.delta_time;

    if world.resources.input.keyboard.is_key_pressed(KeyCode::Space) {
        self.jump();
    }

    world.resources.graphics.bloom_enabled = true;
}
}

Resource catalogue

Time and window

Resource	Type	Description
`window`	`Window`	Window handle, timing data, and display info
`secondary_windows`	`SecondaryWindows`	State for additional windows
`window.timing`	`WindowTiming`	`delta_time`, `frames_per_second`, `uptime_milliseconds`

Input

Resource	Type	Description
`input`	`Input`	Aggregated keyboard, mouse, and gamepad state
`input.keyboard`	`Keyboard`	Per-key state, `is_key_pressed`, `just_pressed`
`input.mouse`	`Mouse`	Position, delta, button state, scroll

Graphics

Resource	Type	Description
`graphics`	`Graphics`	All rendering settings
`graphics.atmosphere`	`Atmosphere`	Sky mode (None, Color, Sky)
`graphics.bloom_enabled`	`bool`	Bloom toggle
`graphics.ssao_enabled`	`bool`	SSAO toggle
`graphics.color_grading`	`ColorGrading`	Tonemapping, gamma, saturation, brightness, contrast

Caches

Resource	Type	Description
`mesh_cache`	`MeshCache`	Loaded mesh data by name
`material_registry`	`MaterialRegistry`	Registered materials
`texture_cache`	`TextureCache`	GPU textures
`animation_cache`	`AnimationCache`	Animation clip data
`prefab_cache`	`PrefabCache`	Loaded prefab templates
`text_cache`	`TextCache`	Font atlas and glyph data

Scene

Resource	Type	Description
`active_camera`	`Option<Entity>`	The camera the renderer pulls from
`children_cache`	`HashMap<Entity, Vec<Entity>>`	Parent-to-children mapping
`entity_names`	`HashMap<String, Entity>`	Name-to-entity lookup
`transform_dirty_entities`	`Vec<Entity>`	Entities that need transform propagation

Simulation

Resource	Type	Feature
`physics`	`PhysicsWorld`	`physics`
`audio`	`AudioEngine`	`audio`
`navmesh`	`NavMeshWorld`	always

Communication

Resource	Type	Description
`event_bus`	`EventBus`	Cross-system message queue
`command_queue`	`Vec<WorldCommand>`	Deferred GPU and scene operations
`frame_schedule`	`FrameSchedule`	Ordered list of engine systems dispatched each frame

Platform

Resource	Type	Feature
`steam`	`SteamResources`	`steam`

Feature-gated resources

Resources whose subsystems are optional only exist when the relevant feature flag is on. Guard access with cfg.

#![allow(unused)]
fn main() {
#[cfg(feature = "physics")]
{
    world.resources.physics.gravity = Vec3::new(0.0, -9.81, 0.0);
}

#[cfg(feature = "audio")]
{
    world.resources.audio.master_volume = 0.8;
}
}

World commands

Operations that need GPU access, or that have to happen at a defined point in the frame, go through world.queue_command. The command queue is a Vec<WorldCommand> that the renderer drains at frame setup.

#![allow(unused)]
fn main() {
world.queue_command(WorldCommand::LoadTexture {
    name: "my_texture".to_string(),
    rgba_data: texture_bytes,
    width: 256,
    height: 256,
});

world.queue_command(WorldCommand::DespawnRecursive { entity });
world.queue_command(WorldCommand::LoadHdrSkybox { hdr_data });
world.queue_command(WorldCommand::CaptureScreenshot { path: None });
}

The render-time commands are GPU uploads and screenshot captures. The ECS-time commands (DespawnRecursive, ReloadMaterial) are drained by the process_commands_system in the frame schedule. The full breakdown of immediate-versus-deferred operations is in Tags, Events, and Commands.

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Nightshade Game Engine