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Extract and start creating a physics engine

This commit is contained in:
Savanni D'Gerinel 2024-02-06 08:54:21 -05:00
parent 1a7776b335
commit 7364b81d10
5 changed files with 357 additions and 90 deletions
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1
Cargo.lock generated
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@ -1021,6 +1021,7 @@ dependencies = [
"async-channel 2.1.1",
"async-std",
"cairo-rs",
"cool_asserts",
"gio",
"glib",
"glib-build-tools 0.17.10",

3
falling-sand/Cargo.toml
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@ -15,5 +15,8 @@ glib = { version = "0.18" }
gtk = { version = "0.7", package = "gtk4", features = [ "v4_10" ] }
tokio = { version = "1", features = [ "full" ] }
[dev-dependencies]
cool_asserts = "*"
[build-dependencies]
glib-build-tools = "0.17"

179
falling-sand/src/main.rs
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@ -1,15 +1,44 @@
use async_channel::Sender;
use async_std::task;
use glib::Object;
use gtk::{prelude::*, subclass::prelude::*};
use std::{cell::RefCell, time::Duration};
use std::{
cell::RefCell,
sync::{Arc, RwLock},
time::Duration,
};
const WIDTH: usize = 601;
const HEIGHT: usize = 601;
const CELL_SIZE: usize = 10;
/*
mod sand_area;
use sand_area::{SandArea, CELL_SIZE, HEIGHT, WIDTH};
*/
#[derive(Debug, Default)]
mod profile;
use profile::profile;
mod physics;
use physics::World;
pub const WIDTH: usize = 601;
pub const HEIGHT: usize = 601;
pub const CELL_SIZE: usize = 1;
const FPS: u64 = 60;
#[derive(Debug)]
pub struct SandViewPrivate {
area: RefCell<SandArea>,
rendering: RefCell<bool>,
last_update: RefCell<std::time::Instant>,
// area: RefCell<SandArea>,
}
impl Default for SandViewPrivate {
fn default() -> Self {
Self {
rendering: RefCell::new(false),
last_update: RefCell::new(std::time::Instant::now()),
// area: RefCell::new(SandArea::default()),
}
}
}
#[glib::object_subclass]
@ -36,9 +65,11 @@ impl Default for SandView {
s.set_draw_func({
let s = s.clone();
move |_, context, width, height| {
profile("redraw", || {
context.set_source_rgb(0., 0., 0.);
let _ = context.paint();
context.set_source_rgb(0.1, 0.1, 0.1);
/*
for x in (0..width).step_by(CELL_SIZE) {
context.move_to(x as f64, 0.);
context.line_to(x as f64, HEIGHT as f64);
@ -48,7 +79,8 @@ impl Default for SandView {
context.line_to(WIDTH as f64, y as f64);
}
let _ = context.stroke();
*/
/*
let area = s.imp().area.borrow();
for x in 0..area.width {
for y in 0..area.height {
@ -58,14 +90,16 @@ impl Default for SandView {
context.set_source_rgb(0., 0., 0.);
}
context.rectangle(
(x * CELL_SIZE + 1) as f64,
(y * CELL_SIZE + 1) as f64,
(CELL_SIZE - 2) as f64,
(CELL_SIZE - 2) as f64,
(x * CELL_SIZE) as f64,
(y * CELL_SIZE) as f64,
(CELL_SIZE) as f64,
(CELL_SIZE) as f64,
);
}
}
let _ = context.fill();
}
}
*/
})
}
});
@ -74,84 +108,77 @@ impl Default for SandView {
}
impl SandView {
/*
fn set_area(&self, area: SandArea) {
*self.imp().area.borrow_mut() = area;
self.queue_draw();
}
*/
fn set_last_update(&self, now: std::time::Instant) {
*self.imp().last_update.borrow_mut() = now;
}
#[derive(Clone, Debug)]
struct SandArea {
width: usize,
height: usize,
grains: Vec<bool>,
}
impl Default for SandArea {
fn default() -> Self {
let width = WIDTH / CELL_SIZE;
let height = HEIGHT / CELL_SIZE;
Self {
width,
height,
grains: vec![false; width * height],
}
}
}
impl SandArea {
pub fn add_grain(&mut self, x: usize, y: usize) {
let addr = self.addr(x, y);
self.grains[addr] = true;
}
pub fn grain(&self, x: usize, y: usize) -> bool {
self.grains[self.addr(x, y)]
}
pub fn tick(self) -> Self {
let mut new_grains = vec![false; self.width * self.height];
for x in 0..self.width {
for y in 1..self.height {
let addr_above = self.addr(x, y - 1);
let addr = self.addr(x, y);
new_grains[addr] = self.grains[addr_above];
}
}
Self {
width: self.width,
height: self.height,
grains: new_grains,
}
}
fn addr(&self, x: usize, y: usize) -> usize {
y * self.width + x
fn last_update(&self) -> std::time::Instant {
self.imp().last_update.borrow().clone()
}
}
/*
async fn animate(sender: Sender<SandArea>) {
let mut sand_area = SandArea::default();
sand_area.add_grain(20, 20);
loop {
std::thread::sleep(Duration::from_millis(1000 / 60));
sand_area = sand_area.tick();
std::thread::sleep(Duration::from_millis(1000 / FPS));
sand_area = profile("next", || sand_area.next());
sender.send(sand_area.clone()).await;
}
}
*/
async fn run_physics(world: World) {
let mut last_update = std::time::Instant::now();
let physics_tickspeed = std::time::Duration::from_millis(1000 / 60);
loop {
let now = std::time::Instant::now();
profile("world next", || world.next(now - last_update));
last_update = wait_for_update(last_update, physics_tickspeed).await;
}
}
async fn wait_for_update(
last_update: std::time::Instant,
tickspeed: std::time::Duration,
) -> std::time::Instant {
let now = std::time::Instant::now();
let next_update = last_update + tickspeed;
task::sleep(next_update - now).await;
std::time::Instant::now()
}
fn main() {
let app = gtk::Application::builder()
.application_id("com.luminescent-dreams.falling-sand")
.build();
let (sender, receiver) = async_channel::bounded(5);
// let (sender, receiver) = async_channel::bounded(5);
let world = World::default();
let runtime = tokio::runtime::Builder::new_multi_thread()
.enable_all()
.build()
.unwrap();
let physics_thread = runtime.spawn(run_physics(world.clone()));
/*
let background_thread = runtime.spawn(animate(sender));
*/
/*
let sand_area = Arc::new(RwLock::new(SandArea::default()));
*/
app.connect_activate(move |app| {
let window = gtk::ApplicationWindow::new(app);
@ -162,10 +189,27 @@ fn main() {
glib::spawn_future_local({
let view = view.clone();
let receiver = receiver.clone();
view.set_last_update(std::time::Instant::now());
let fps_delay = std::time::Duration::from_millis(1000 / FPS);
// let sand_area = sand_area.clone();
println!("FPS delay: {:?}", fps_delay);
async move {
while let Ok(area) = receiver.recv().await {
view.set_area(area);
loop {
/*
profile("setting area", || {
view.set_area(sand_area.read().unwrap().clone())
});
*/
// Now, determine how much time remains before the next update. This can vary frame by frame, based on how much rendering has to be done.
let now = std::time::Instant::now();
let mut wait_time = (view.last_update() + fps_delay) - now;
if wait_time < std::time::Duration::from_millis(0) {
wait_time = fps_delay;
}
view.set_last_update(now);
async_std::task::sleep(wait_time).await;
}
}
});
@ -173,5 +217,6 @@ fn main() {
app.run();
let _ = runtime.block_on(background_thread);
// let _ = runtime.block_on(background_thread);
let _ = runtime.block_on(physics_thread);
}

191
falling-sand/src/physics.rs Normal file
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@ -0,0 +1,191 @@
use crate::profile;
use std::sync::{Arc, RwLock};
const GRAVITY: f64 = 1.;
fn within(val1: f64, val2: f64, tolerance: f64) -> bool {
(val1 - val2).abs() <= tolerance
}
#[derive(Clone, Copy, Debug, PartialEq)]
struct Point {
x: f64,
y: f64,
}
impl Point {
fn distance_sq(&self, other: &Point) -> f64 {
let xdist = other.x - self.x;
let ydist = other.y - self.y;
xdist * xdist + ydist * ydist
}
fn eq(&self, other: &Point, tolerance: f64) -> bool {
within(self.x, other.x, tolerance) && within(self.y, other.y, tolerance)
}
}
#[derive(Clone, Copy, Debug, PartialEq)]
struct Vector {
dx: f64,
dy: f64,
}
#[derive(Clone, Copy, Debug, PartialEq)]
struct Grain {
radius: f64,
location: Point,
velocity: Vector,
}
impl Grain {
fn move_by(&mut self, delta_t: std::time::Duration) {
self.location.x = self.location.x + self.velocity.dx * (delta_t.as_secs_f64());
self.location.y = self.location.y + self.velocity.dy * (delta_t.as_secs_f64());
}
}
#[derive(Clone, Default)]
pub struct World {
grains: Arc<RwLock<Vec<Grain>>>,
}
impl World {
pub fn new() -> Self {
Self {
grains: Arc::new(RwLock::new(vec![])),
}
}
pub fn add_grain(&self, grain: Grain) {
self.grains.write().unwrap().push(grain);
}
pub fn grain_count(&self) -> usize {
self.grains.read().unwrap().len()
}
pub fn grains(&self) -> Vec<Grain> {
self.grains.read().unwrap().clone()
}
pub fn next(&self, delta_t: std::time::Duration) {
self.move_objects(delta_t);
}
fn move_objects(&self, delta_t: std::time::Duration) {
for grain in self.grains.write().unwrap().iter_mut() {
grain.move_by(delta_t);
}
}
}
pub trait Collision {
type Other;
fn collision_depth(&self, other: &Self::Other) -> Option<f64>;
}
impl Collision for Grain {
type Other = Grain;
fn collision_depth(&self, other: &Self::Other) -> Option<f64> {
let radii = (self.radius + other.radius) * (self.radius + other.radius);
let distance = self.location.distance_sq(&other.location);
if distance < radii {
Some(radii.sqrt() - distance.sqrt())
} else {
None
}
}
}
#[cfg(test)]
mod test {
use super::*;
use cool_asserts::assert_matches;
#[test]
fn it_detects_grain_grain_collision() {
let grain_1 = Grain {
radius: 10.,
location: Point { x: 0., y: 0. },
velocity: Vector { dx: 0., dy: 0. },
};
let grain_2 = Grain {
radius: 10.,
location: Point { x: 1., y: 0. },
velocity: Vector { dx: 0., dy: 0. },
};
let grain_3 = Grain {
radius: 4.,
location: Point { x: 15., y: 0. },
velocity: Vector { dx: 0., dy: 0. },
};
assert_matches!(grain_1.collision_depth(&grain_2), Some(v) => {
assert!(within(v, 19., 0.1));
} );
assert_matches!(grain_1.collision_depth(&grain_3), None);
}
#[test]
fn it_moves_a_grain_according_to_time() {
let mut grain_1 = Grain {
radius: 10.,
location: Point { x: 0., y: 0. },
velocity: Vector { dx: 5., dy: 5. },
};
grain_1.move_by(std::time::Duration::from_millis(500));
let dest = Point { x: 2.5, y: 2.5 };
assert!(grain_1.location.eq(&dest, 0.001));
}
#[test]
fn it_moves_many_grains() {
let grain_1 = Grain {
radius: 5.,
location: Point { x: 0., y: 0. },
velocity: Vector { dx: 0., dy: -1. },
};
let grain_1_b = Grain {
location: Point { x: 0., y: -0.5 },
..grain_1
};
let grain_2 = Grain {
radius: 5.,
location: Point { x: 5., y: 5. },
velocity: Vector { dx: 0., dy: 1. },
};
let grain_2_b = Grain {
location: Point { x: 5., y: 5.5 },
..grain_2
};
let grain_3 = Grain {
radius: 5.,
location: Point { x: 15., y: 0. },
velocity: Vector { dx: 1., dy: 1. },
};
let grain_3_b = Grain {
location: Point { x: 15.5, y: 0.5 },
..grain_3
};
let world = World::new();
world.add_grain(grain_1);
world.add_grain(grain_2);
world.add_grain(grain_3);
world.next(std::time::Duration::from_millis(500));
let grains = world.grains();
for grain in grains {
let tolerance = 0.001;
assert!(
grain.location.eq(&grain_1_b.location, tolerance)
|| grain.location.eq(&grain_2_b.location, tolerance)
|| grain.location.eq(&grain_3_b.location, tolerance)
);
}
}
}

27
falling-sand/src/profile.rs Normal file
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@ -0,0 +1,27 @@
pub fn profile<F, T>(tag: &str, f: F) -> T
where
F: FnOnce() -> T,
{
let start_time = std::time::Instant::now();
let retval = f();
let end_time = std::time::Instant::now();
println!("[{}] {:?}", tag, end_time - start_time);
retval
}
/*
struct Profile {
metric: Arc<RwLock<HashMap<String, [f64; 100]>>>,
receiver: async_channel::Receiver<(String, f64)>,
}
impl Profile {
async fn run(&self) {
loop {
if let Ok(name, value) = self.receiver.recv().await {
self.metric.write().unwrap().entry(name).and_modify(|metric| metric.).or_insert(vec![0.; 100]);
}
}
}
}
*/