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use crate::{
contact_generators::{Contact, ContactGenerator},
contact_resolver::ContactResolver,
force_generators::ForceGenerator,
force_registry::ForceRegistry,
particle::Particle,
FP,
};
use std::ptr;
use vek2d::Vec2d;
/// The `World` contains the many parts of a physics engine, such
/// as a force registry for multiple forces, a contact resolver,
/// multiple contact generators, and contacts generated.
pub struct World {
calc_iterations: bool,
registry: ForceRegistry,
resolver: ContactResolver,
contact_generators: Vec<Box<dyn ContactGenerator>>,
contacts: Vec<Contact>,
max_contacts: i32,
particle_free_slots: Vec<usize>,
particle_array: Vec<Option<Particle>>,
}
impl World {
/// Initialise a new particle physics world
///
/// # Example
///
/// ```
/// use cyclone2d::world::World;
///
/// let mut particle_world = World::new(1000, 1000, None);
/// ```
pub fn new(
particle_capacity: usize,
max_contacts: usize,
iterations: Option<u16>,
) -> World {
let mut contacts = Vec::with_capacity(max_contacts);
for _ in 0..max_contacts {
contacts.push(Contact::default());
}
World {
calc_iterations: iterations.is_none(),
registry: ForceRegistry::new(),
resolver: ContactResolver::new(iterations.unwrap_or(0)),
contact_generators: Vec::new(),
contacts,
max_contacts: max_contacts as i32,
particle_free_slots: Vec::new(),
particle_array: Vec::with_capacity(particle_capacity),
}
}
/// Called at the start of a frame to be drawn
#[inline]
pub fn start_frame(&mut self) {
for v in self.particle_array.iter_mut() {
if let Some(p) = v {
p.clear_forces();
}
}
}
/// Moves a created `Particle` in to the `World` particle array, returning
/// an index number which functions as the particle ID
#[inline]
pub fn add_particle(&mut self, particle: Particle) -> Option<usize> {
if self.particle_array.len() >= self.particle_array.capacity() {
return None;
}
let slot;
if let Some(free) = self.particle_free_slots.pop() {
slot = free;
self.particle_array[slot] = Some(particle);
} else {
slot = self.particle_array.len();
self.particle_array.push(Some(particle));
}
Some(slot)
}
/// Get a reference to `Particle` located at index number (`id`).
#[inline]
pub fn get_particle_position(&self, id: usize) -> Option<Vec2d<FP>> {
if let Some(p) = self.particle_array.get(id) {
if let Some(p) = p {
return Some(p.position());
}
}
None
}
#[inline]
pub fn get_particle(&self, id: usize) -> Option<&Particle> {
if let Some(p) = self.particle_array.get(id) {
if p.is_some() {
return p.as_ref();
}
}
None
}
#[inline]
pub fn get_particle_mut(&mut self, id: usize) -> Option<&mut Particle> {
if let Some(p) = self.particle_array.get_mut(id) {
if p.is_some() {
return p.as_mut();
}
}
None
}
#[inline]
pub fn get_particle_ptr(
&mut self,
id: usize,
) -> Option<ptr::NonNull<Particle>> {
if let Some(p) = self.particle_array.get_mut(id) {
if let Some(p) = p.as_mut() {
return Some(p.as_non_null_ptr());
}
}
None
}
/// Also removes any force or contact generators attached to this index
pub fn rm_particle(&mut self, id: usize) {
// TODO: get pointer from id, check generators for use
if id < self.particle_array.len() - 1 {
if let Some(slot) = self.particle_array.get_mut(id) {
if let Some(particle) = slot {
// make the pointer a usize for comparisons
let ptr_uzise =
particle.as_non_null_ptr().as_ptr() as usize;
// do registry first
self.registry.remove_if_contains(ptr_uzise);
// need to loop, remove, reset since the array changes
'removal: loop {
let mut index = 0;
for (i, cg) in
self.contact_generators.iter().enumerate()
{
if cg.contains_ptr(ptr_uzise) {
index = i;
break;
}
if i >= self.contact_generators.len() - 1 {
break 'removal;
}
}
self.contact_generators.remove(index);
}
}
}
self.particle_array[id] = None;
self.particle_free_slots.push(id);
}
}
#[inline]
pub fn get_particle_array(&self) -> &Vec<Option<Particle>> {
&self.particle_array
}
/// Add a new `ForceGenerator` to the particle physics world
///
/// ```
/// use cyclone2d::{
/// world::World,
/// force_generators::Gravity
/// };
/// use cyclone2d::particle::Particle;
///
/// let mut particle_world = World::new(100, 1000, None);
/// // Create a default particle
/// let particle = Particle::default();
/// // Add it and get the slot ID back
/// let pid = particle_world.add_particle(particle).unwrap();
/// // Slot ID is used to get the pointer to the particle
/// let ptr = particle_world.get_particle_ptr(pid).unwrap();
/// // Almost all generators require pointers to the particles to act on
/// // Because the engine inherrently assumes that 0 is down while
/// // positive floats are up, gravity here is a negative value
/// particle_world.add_force_generator(Gravity::new(ptr, -9.81));
/// ```
#[inline]
pub fn add_force_generator(
&mut self,
force: impl ForceGenerator + 'static,
) {
self.registry.add(force);
}
/// Add a new `ForceGenerator` to the particle physics world
///
/// ```
/// use cyclone2d::{
/// world::World,
/// contact_generators::GroundContact
/// };
///
/// let mut particle_world = World::new(100, 1000, None);
/// particle_world.add_contact_generator(GroundContact::new());
/// ```
#[inline]
pub fn add_contact_generator(
&mut self,
force: impl ContactGenerator + 'static,
) {
self.contact_generators.push(Box::new(force));
}
#[inline]
fn generate_contacts(&mut self) -> usize {
let mut limit = self.max_contacts;
for cg in &self.contact_generators {
let start_index = self.contacts.len() - limit as usize;
let used = cg.add_contact(
&mut self.contacts[start_index..],
&mut self.particle_array,
limit as u32,
);
limit -= used as i32;
if limit <= 0 {
break;
}
}
(self.max_contacts - limit) as usize
}
#[inline]
fn integrate(&mut self, dt: FP) {
for v in self.particle_array.iter_mut() {
if let Some(p) = v {
p.integrate(dt);
}
}
}
#[inline]
pub fn run_physics(&mut self, dt: FP) {
self.registry.update_forces();
self.integrate(dt);
let used_contacts = self.generate_contacts();
if used_contacts > 0 {
if self.calc_iterations {
self.resolver.set_iterations(used_contacts as u16 * 2);
}
self.resolver.resolve_contacts(
&mut self.contacts,
used_contacts,
dt,
);
}
}
}
impl Particle {
#[inline]
fn integrate(&mut self, dt: FP) {
if self.inverse_mass() <= 0.0 {
return;
}
// update linear position
self.set_position(self.position() + self.velocity() * dt);
// work out forces
let mut acceleration = self.acceleration();
acceleration += self.forces() * self.inverse_mass();
// Update linear velocity
self.set_velocity(self.velocity() + acceleration * dt);
// damping required to avoid float errors
self.set_velocity(self.velocity() * self.damping().powf(dt));
self.clear_forces();
}
}