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bevy game state manager prototype
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use super::states; | |
use bevy::{prelude::*, ecs::{Schedule, ThreadLocalExecution, SystemId, TypeAccess, ArchetypeAccess, ParallelExecutor}}; | |
use std::borrow::Cow; | |
pub struct GamePlugin; | |
impl Plugin for GamePlugin { | |
fn build(&self, app: &mut AppBuilder) { | |
app | |
.add_resource(GameState::Stage1(SubState::Done)) | |
.add_resource(GameTick::default()) | |
.add_stage_before("pre_update", "game_update") | |
.add_system_to_stage("game_update", Box::new(GameStateManager::new())) | |
; | |
} | |
} | |
// A Resource that tracks the fixed game rate | |
pub struct GameTick { | |
pub rate: f64, | |
pub tick: u64, | |
} | |
// A Resource that tracks the current state | |
#[derive(Debug, Copy, Clone)] | |
pub enum GameState { | |
Stage1(SubState), | |
Stage2, | |
Stage3(SubState), | |
GameStart, | |
Game, | |
} | |
// Packs the schedule and executor together | |
pub struct StateSchedule(pub Schedule, pub ParallelExecutor); | |
impl Default for StateSchedule { | |
fn default() -> Self { | |
StateSchedule(Default::default(), ParallelExecutor::without_tracker_clears()) | |
} | |
} | |
impl StateSchedule { | |
fn run(&mut self, mut world: &mut World, mut resources: &mut Resources) { | |
self.0.initialize(world, resources); | |
self.1.run(&mut self.0, &mut world, &mut resources); | |
} | |
} | |
// The GSM is a System that runs one of multiple states | |
// It will run the Game state at a fixed rate as specified by the GameTick Resource | |
pub struct GameStateManager { | |
pub resource_access: TypeAccess, | |
pub id: SystemId, | |
pub archetype_access: ArchetypeAccess, | |
pub acc: f64, // accumulator for fixed game ticks | |
pub stage_1: StateSchedule, // Loads the loading screen | |
pub stage_2: StateSchedule, // Shows the loading screen | |
pub stage_3: StateSchedule, // Loads the rest of our assets | |
pub game_start: StateSchedule, // Hides the loading screen, preps game state | |
pub game: StateSchedule, // Runs at a fixed rate | |
} | |
impl GameStateManager { | |
pub fn new() -> Self { | |
GameStateManager { | |
resource_access: Default::default(), | |
id: SystemId::new(), | |
archetype_access: Default::default(), | |
acc: 0.0, | |
stage_1: Default::default(), | |
stage_2: Default::default(), | |
stage_3: Default::default(), | |
game_start: Default::default(), | |
game: Default::default() | |
} | |
} | |
} | |
impl System for GameStateManager { | |
fn name(&self) -> Cow<'static, str> { "GSM".into() } | |
fn id(&self) -> SystemId { self.id } | |
fn update_archetype_access(&mut self, _world: &World) { self.archetype_access.clear(); } | |
fn archetype_access(&self) -> &ArchetypeAccess { &self.archetype_access } | |
fn resource_access(&self) -> &TypeAccess { &self.resource_access } | |
fn thread_local_execution(&self) -> ThreadLocalExecution { ThreadLocalExecution::Immediate } | |
fn run(&mut self, _world: &World, _resources: &Resources) { } | |
fn run_thread_local(&mut self, mut world: &mut World, mut resources: &mut Resources) { | |
let state = *resources.get::<GameState>().unwrap(); // copy the state to avoid borrow issues | |
match state { | |
GameState::Stage1(_) => self.stage_1.run(&mut world, &mut resources), | |
GameState::Stage2 => self.stage_2.run(&mut world, &mut resources), | |
GameState::Stage3(_) => self.stage_3.run(&mut world, &mut resources), | |
GameState::GameStart => self.game_start.run(&mut world, &mut resources), | |
GameState::Game => { | |
let rate = match (resources.get::<Time>(), resources.get::<GameTick>()) { | |
(Some(time), Some(rate)) => { | |
self.acc += time.delta_seconds_f64; | |
Some(rate.rate) | |
}, | |
_ => { None }, | |
}; | |
// We had to capture the rate to avoid borrow issues | |
match rate { | |
Some(rate) => { | |
// Run the schedule at fixed interval | |
while self.acc >= rate { | |
self.game.run(world, resources); | |
self.acc -= rate; | |
} | |
}, | |
_ => {}, | |
} | |
}, | |
} | |
} | |
fn initialize(&mut self, _world: &mut World, _resources: &mut Resources) { | |
/* ie | |
pub fn initialize(schedule: &mut Schedule) { | |
schedule.add_stage("update"); | |
schedule.add_system_to_stage("update", do_stuff.system()); | |
} | |
*/ | |
states::stage_1::initialize(&mut self.stage_1.0); | |
states::stage_2::initialize(&mut self.stage_2.0); | |
states::stage_3::initialize(&mut self.stage_3.0); | |
states::game_start::initialize(&mut self.game_start.0); | |
states::game::initialize(&mut self.game.0); | |
} | |
} |
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