bevy_system_graph
This crate provides the utilities for creating strictly ordered execution graphs of systems for the Bevy game engine.
Bevy Version Supported
| Bevy Version | bevy_system_graph |
|---|---|
| 0.1 | 0.6 |
Starting a Graph
To start building a system graph, one or more systems must be added to the graph as root nodes. Root systems have no dependencies within the graph.
let graph = SystemGraph::new();
// Create a root system for the graph.
let root_a = graph.root(sys_a);
// Graphs can have multiple root nodes.
let root_b = graph.root(sys_b);
let root_c = graph.root(sys_c);
Using SystemLabels
Systems can still use labels to establish the ordering of systems relative to other systems outside of the graph.
let graph = SystemGraph::new();
let root_a = graph.root(
sys_a
.label("Physics")
.before("Propagate Transforms")
);
Conversion into SystemSet
To ease adding all of the graph's systems into a Schedule, both SystemGraph and SystemGraphNode implement Into.
let graph = SystemGraph::new();
let root_a = graph.root(sys_a);
// Convert into a SystemSet
let system_set: SystemSet = graph.into();
Sequential Execution
Graph nodes can be sequentially chained via SystemGraphNode::then. This creates a new node from a system and adds a "after" dependency on the original system.
let graph = SystemGraph::new();
graph
.root(sys_a)
.then(sys_b)
.then(sys_c);
// Convert into a SystemSet
let system_set: SystemSet = graph.into();
Fan Out
SystemGraphNode::fork can be used to fan out into multiple branches. All fanned out systems will not execute until the original has finished, but do not have a mutual dependency on each other.
let graph = SystemGraph::new();
// Fork out from one original node.
// sys_b, sys_c, and sys_d will only start when sys_a finishes.
let (c, b, d) = graph.root(sys_a)
.fork((
sys_b,
sys_c,
sys_d,
));
// Alternatively, calling "then" repeatedly achieves the same thing.
let e = d.then(sys_e);
let f = d.then(sys_f);
// Convert into a SystemSet
let system_set: SystemSet = graph.into();
Fan In
A graph node can wait on multiple systems before running via SystemJoin::join. The system will not run until all prior systems are finished.
let graph = SystemGraph::new();
let start_a = graph.root(sys_a);
let start_b = graph.root(sys_b);
let start_c = graph.root(sys_c);
(start_a, start_b, start_c)
.join(sys_d)
.then(sys_e);
// Convert into a SystemSet
let system_set: SystemSet = graph.into();
Fan Out into Fan In
The types used to implement fork and join are composable.
let graph = SystemGraph::new();
graph.root(sys_a)
.fork((sys_b, sys_c, sys_d))
.join(sys_e)
.then(sys_f);
// Convert into a SystemSet
let system_set: SystemSet = graph.into();
Cloning
Individual [graph nodes] are backed by a Rc, so cloning it will still point to the same logical underlying graph.
3 Sep 17, 2023
11 May 28, 2023
11 Dec 18, 2023
2 Jul 15, 2022
0 Dec 26, 2021
20 Dec 23, 2022
65 Feb 20, 2023
28 Sep 12, 2022
27 Jan 7, 2023
100 Jan 1, 2023
85 Dec 23, 2022
517 Dec 31, 2022
79 Nov 2, 2022
947 Jan 8, 2023
52 Nov 14, 2022
24 Oct 28, 2022
20 Apr 21, 2022
150 Jan 7, 2023
48 Nov 28, 2022