veloren/common/sys/src/phys.rs

789 lines
33 KiB
Rust

use common::{
comp::{
BeamSegment, CharacterState, Collider, Gravity, Mass, Mounting, Ori, PhysicsState, Pos,
PreviousPhysCache, Projectile, Scale, Shockwave, Sticky, Vel,
},
consts::{FRIC_GROUND, GRAVITY},
event::{EventBus, ServerEvent},
metrics::{PhysicsMetrics, SysMetrics},
resources::DeltaTime,
span,
terrain::{Block, TerrainGrid},
uid::Uid,
vol::ReadVol,
};
use rayon::iter::ParallelIterator;
use specs::{
Entities, Join, ParJoin, Read, ReadExpect, ReadStorage, System, WriteExpect, WriteStorage,
};
use std::ops::Range;
use vek::*;
pub const BOUYANCY: f32 = 1.0;
// Friction values used for linear damping. They are unitless quantities. The
// value of these quantities must be between zero and one. They represent the
// amount an object will slow down within 1/60th of a second. Eg. if the
// friction is 0.01, and the speed is 1.0, then after 1/60th of a second the
// speed will be 0.99. after 1 second the speed will be 0.54, which is 0.99 ^
// 60.
pub const FRIC_AIR: f32 = 0.0125;
pub const FRIC_FLUID: f32 = 0.4;
// Integrates forces, calculates the new velocity based off of the old velocity
// dt = delta time
// lv = linear velocity
// damp = linear damping
// Friction is a type of damping.
fn integrate_forces(dt: f32, mut lv: Vec3<f32>, grav: f32, damp: f32) -> Vec3<f32> {
// this is not linear damping, because it is proportional to the original
// velocity this "linear" damping in in fact, quite exponential. and thus
// must be interpolated accordingly
let linear_damp = (1.0 - damp.min(1.0)).powf(dt * 60.0);
// TODO: investigate if we can have air friction provide the neccessary limits
// here
lv.z = (lv.z - grav * dt).max(-80.0).min(lv.z);
lv * linear_damp
}
fn calc_z_limit(
char_state_maybe: Option<&CharacterState>,
collider: Option<&Collider>,
) -> (f32, f32) {
let modifier = if char_state_maybe.map_or(false, |c_s| c_s.is_dodge()) {
0.5
} else {
1.0
};
collider
.map(|c| c.get_z_limits(modifier))
.unwrap_or((-0.5 * modifier, 0.5 * modifier))
}
/// This system applies forces and calculates new positions and velocities.
pub struct Sys;
impl<'a> System<'a> for Sys {
#[allow(clippy::type_complexity)]
type SystemData = (
Entities<'a>,
ReadStorage<'a, Uid>,
ReadExpect<'a, TerrainGrid>,
Read<'a, DeltaTime>,
ReadExpect<'a, SysMetrics>,
WriteExpect<'a, PhysicsMetrics>,
Read<'a, EventBus<ServerEvent>>,
ReadStorage<'a, Scale>,
ReadStorage<'a, Sticky>,
ReadStorage<'a, Mass>,
ReadStorage<'a, Collider>,
ReadStorage<'a, Gravity>,
WriteStorage<'a, PhysicsState>,
WriteStorage<'a, Pos>,
WriteStorage<'a, Vel>,
WriteStorage<'a, Ori>,
WriteStorage<'a, PreviousPhysCache>,
ReadStorage<'a, Mounting>,
ReadStorage<'a, Projectile>,
ReadStorage<'a, BeamSegment>,
ReadStorage<'a, Shockwave>,
ReadStorage<'a, CharacterState>,
);
#[allow(clippy::or_fun_call)] // TODO: Pending review in #587
#[allow(clippy::blocks_in_if_conditions)] // TODO: Pending review in #587
fn run(
&mut self,
(
entities,
uids,
terrain,
dt,
sys_metrics,
mut physics_metrics,
event_bus,
scales,
stickies,
masses,
colliders,
gravities,
mut physics_states,
mut positions,
mut velocities,
mut orientations,
mut previous_phys_cache,
mountings,
projectiles,
beams,
shockwaves,
char_states,
): Self::SystemData,
) {
let start_time = std::time::Instant::now();
span!(_guard, "run", "phys::Sys::run");
let mut event_emitter = event_bus.emitter();
// Add/reset physics state components
span!(guard, "Add/reset physics state components");
for (entity, _, _, _, _) in (
&entities,
&colliders,
&positions,
&velocities,
&orientations,
)
.join()
{
let _ = physics_states
.entry(entity)
.map(|e| e.or_insert_with(Default::default));
}
drop(guard);
// Apply pushback
//
// Note: We now do this first because we project velocity ahead. This is slighty
// imperfect and implies that we might get edge-cases where entities
// standing right next to the edge of a wall may get hit by projectiles
// fired into the wall very close to them. However, this sort of thing is
// already possible with poorly-defined hitboxes anyway so it's not too
// much of a concern.
//
// If this situation becomes a problem, this code should be integrated with the
// terrain collision code below, although that's not trivial to do since
// it means the step needs to take into account the speeds of both
// entities.
span!(guard, "Maintain pushback cache");
//Add PreviousPhysCache for all relevant entities
for entity in (
&entities,
&velocities,
&positions,
!&previous_phys_cache,
!&mountings,
!&beams,
!&shockwaves,
)
.join()
.map(|(e, _, _, _, _, _, _)| e)
.collect::<Vec<_>>()
{
let _ = previous_phys_cache.insert(entity, PreviousPhysCache {
velocity_dt: Vec3::zero(),
center: Vec3::zero(),
collision_boundary: 0.0,
scale: 0.0,
scaled_radius: 0.0,
});
}
//Update PreviousPhysCache
for (_, vel, position, mut phys_cache, collider, scale, cs, _, _, _) in (
&entities,
&velocities,
&positions,
&mut previous_phys_cache,
colliders.maybe(),
scales.maybe(),
char_states.maybe(),
!&mountings,
!&beams,
!&shockwaves,
)
.join()
{
let scale = scale.map(|s| s.0).unwrap_or(1.0);
let z_limits = calc_z_limit(cs, collider);
let z_limits = (z_limits.0 * scale, z_limits.1 * scale);
let half_height = (z_limits.1 - z_limits.0) / 2.0;
phys_cache.velocity_dt = vel.0 * dt.0;
let entity_center = position.0 + Vec3::new(0.0, z_limits.0 + half_height, 0.0);
let flat_radius = collider.map(|c| c.get_radius()).unwrap_or(0.5) * scale;
let radius = (flat_radius.powi(2) + half_height.powi(2)).sqrt();
// Move center to the middle between OLD and OLD+VEL_DT so that we can reduce
// the collision_boundary
phys_cache.center = entity_center + phys_cache.velocity_dt / 2.0;
phys_cache.collision_boundary = radius + (phys_cache.velocity_dt / 2.0).magnitude();
phys_cache.scale = scale;
phys_cache.scaled_radius = flat_radius;
}
drop(guard);
span!(guard, "Apply pushback");
let metrics = (
&entities,
&positions,
&mut velocities,
&previous_phys_cache,
masses.maybe(),
colliders.maybe(),
!&mountings,
stickies.maybe(),
&mut physics_states,
// TODO: if we need to avoid collisions for other things consider moving whether it
// should interact into the collider component or into a separate component
projectiles.maybe(),
char_states.maybe(),
)
.par_join()
.filter(|(_, _, _, _, _, _, _, sticky, physics, _, _)| {
sticky.is_none() || (physics.on_wall.is_none() && !physics.on_ground)
})
.map(|(e, p, v, vd, m, c, _, _, ph, pr, c_s)| (e, p, v, vd, m, c, ph, pr, c_s))
.fold(
PhysicsMetrics::default,
|mut metrics,
(
entity,
pos,
vel,
previous_cache,
mass,
collider,
physics,
projectile,
char_state_maybe,
)| {
let z_limits = calc_z_limit(char_state_maybe, collider);
let mass = mass.map(|m| m.0).unwrap_or(previous_cache.scale);
// Resets touch_entities in physics
physics.touch_entities.clear();
let is_projectile = projectile.is_some();
let mut vel_delta = Vec3::zero();
for (
entity_other,
other,
pos_other,
previous_cache_other,
mass_other,
collider_other,
_,
_,
_,
_,
char_state_other_maybe,
) in (
&entities,
&uids,
&positions,
&previous_phys_cache,
masses.maybe(),
colliders.maybe(),
!&projectiles,
!&mountings,
!&beams,
!&shockwaves,
char_states.maybe(),
)
.join()
{
let collision_boundary = previous_cache.collision_boundary
+ previous_cache_other.collision_boundary;
if previous_cache
.center
.distance_squared(previous_cache_other.center)
> collision_boundary.powi(2)
|| entity == entity_other
{
continue;
}
let collision_dist =
previous_cache.scaled_radius + previous_cache_other.scaled_radius;
let z_limits_other = calc_z_limit(char_state_other_maybe, collider_other);
let mass_other = mass_other
.map(|m| m.0)
.unwrap_or(previous_cache_other.scale);
//This check after the pos check, as we currently don't have that many
// massless entites [citation needed]
if mass_other == 0.0 {
continue;
}
metrics.entity_entity_collision_checks += 1;
const MIN_COLLISION_DIST: f32 = 0.3;
let increments = ((previous_cache.velocity_dt
- previous_cache_other.velocity_dt)
.magnitude()
/ MIN_COLLISION_DIST)
.max(1.0)
.ceil() as usize;
let step_delta = 1.0 / increments as f32;
let mut collided = false;
for i in 0..increments {
let factor = i as f32 * step_delta;
let pos = pos.0 + previous_cache.velocity_dt * factor;
let pos_other = pos_other.0 + previous_cache_other.velocity_dt * factor;
let diff = pos.xy() - pos_other.xy();
if diff.magnitude_squared() <= collision_dist.powi(2)
&& pos.z + z_limits.1 * previous_cache.scale
>= pos_other.z + z_limits_other.0 * previous_cache_other.scale
&& pos.z + z_limits.0 * previous_cache.scale
<= pos_other.z + z_limits_other.1 * previous_cache_other.scale
{
if !collided {
physics.touch_entities.push(*other);
metrics.entity_entity_collisions += 1;
}
// Don't apply repulsive force to projectiles
if diff.magnitude_squared() > 0.0 && !is_projectile {
let force =
400.0 * (collision_dist - diff.magnitude()) * mass_other
/ (mass + mass_other);
vel_delta += Vec3::from(diff.normalized()) * force * step_delta;
}
collided = true;
}
}
}
// Change velocity
vel.0 += vel_delta * dt.0;
metrics
},
)
.reduce(PhysicsMetrics::default, |old, new| PhysicsMetrics {
entity_entity_collision_checks: old.entity_entity_collision_checks
+ new.entity_entity_collision_checks,
entity_entity_collisions: old.entity_entity_collisions
+ new.entity_entity_collisions,
});
physics_metrics.entity_entity_collision_checks = metrics.entity_entity_collision_checks;
physics_metrics.entity_entity_collisions = metrics.entity_entity_collisions;
drop(guard);
// Apply movement inputs
span!(guard, "Apply movement and terrain collision");
let land_on_grounds = (
&entities,
scales.maybe(),
stickies.maybe(),
&colliders,
&mut positions,
&mut velocities,
&mut orientations,
&mut physics_states,
!&mountings,
)
.par_join()
.fold(Vec::new, |
mut land_on_grounds,
(entity, _scale, sticky, collider, mut pos, mut vel, _ori, mut physics_state, _),
| {
if sticky.is_some() && physics_state.on_surface().is_some() {
vel.0 = Vec3::zero();
return land_on_grounds;
}
// TODO: Use this
//let scale = scale.map(|s| s.0).unwrap_or(1.0);
let old_vel = *vel;
// Integrate forces
// Friction is assumed to be a constant dependent on location
let friction = FRIC_AIR
.max(if physics_state.on_ground {
FRIC_GROUND
} else {
0.0
})
.max(if physics_state.in_liquid.is_some() {
FRIC_FLUID
} else {
0.0
});
let in_loaded_chunk = terrain
.get_key(terrain.pos_key(pos.0.map(|e| e.floor() as i32)))
.is_some();
let downward_force = if !in_loaded_chunk {
0.0 // No gravity in unloaded chunks
} else if physics_state
.in_liquid
.map(|depth| depth > 0.75)
.unwrap_or(false)
{
(1.0 - BOUYANCY) * GRAVITY
} else {
GRAVITY
} * gravities.get(entity).map(|g| g.0).unwrap_or_default();
vel.0 = integrate_forces(dt.0, vel.0, downward_force, friction);
// Don't move if we're not in a loaded chunk
let mut pos_delta = if in_loaded_chunk {
// this is an approximation that allows most framerates to
// behave in a similar manner.
let dt_lerp = 0.2;
(vel.0 * dt_lerp + old_vel.0 * (1.0 - dt_lerp)) * dt.0
} else {
Vec3::zero()
};
match *collider {
Collider::Box {
radius,
z_min,
z_max,
} => {
// Scale collider
// TODO: Use scale & actual proportions when pathfinding is good enough to manage irregular entity
// sizes
let radius = radius.min(0.45); // * scale;
let z_min = z_min; // * scale;
let z_max = z_max.clamped(1.2, 1.95); // * scale;
// Probe distances
let hdist = radius.ceil() as i32;
// Neighbouring blocks iterator
let near_iter = (-hdist..hdist + 1)
.map(move |i| {
(-hdist..hdist + 1).map(move |j| {
(1 - Block::MAX_HEIGHT.ceil() as i32 + z_min.floor() as i32
..z_max.ceil() as i32 + 1)
.map(move |k| (i, j, k))
})
})
.flatten()
.flatten();
// Function for iterating over the blocks the player at a specific position
// collides with
fn collision_iter<'a>(
pos: Vec3<f32>,
terrain: &'a TerrainGrid,
hit: &'a impl Fn(&Block) -> bool,
height: &'a impl Fn(&Block) -> f32,
near_iter: impl Iterator<Item = (i32, i32, i32)> + 'a,
radius: f32,
z_range: Range<f32>,
) -> impl Iterator<Item = Aabb<f32>> + 'a {
near_iter.filter_map(move |(i, j, k)| {
let block_pos = pos.map(|e| e.floor() as i32) + Vec3::new(i, j, k);
if let Some(block) = terrain.get(block_pos).ok().copied().filter(hit) {
let player_aabb = Aabb {
min: pos + Vec3::new(-radius, -radius, z_range.start),
max: pos + Vec3::new(radius, radius, z_range.end),
};
let block_aabb = Aabb {
min: block_pos.map(|e| e as f32),
max: block_pos.map(|e| e as f32)
+ Vec3::new(1.0, 1.0, height(&block)),
};
if player_aabb.collides_with_aabb(block_aabb) {
return Some(block_aabb);
}
}
None
})
}
let z_range = z_min..z_max;
// Function for determining whether the player at a specific position collides
// with blocks with the given criteria
fn collision_with<'a>(
pos: Vec3<f32>,
terrain: &'a TerrainGrid,
hit: impl Fn(&Block) -> bool,
near_iter: impl Iterator<Item = (i32, i32, i32)> + 'a,
radius: f32,
z_range: Range<f32>,
) -> bool {
collision_iter(pos, terrain, &|block| block.is_solid() && hit(block), &Block::solid_height, near_iter, radius, z_range).count()
> 0
}
let was_on_ground = physics_state.on_ground;
physics_state.on_ground = false;
let mut on_ground = false;
let mut on_ceiling = false;
let mut attempts = 0; // Don't loop infinitely here
// Don't jump too far at once
let increments = (pos_delta.map(|e| e.abs()).reduce_partial_max() / 0.3)
.ceil()
.max(1.0);
let old_pos = pos.0;
fn block_true(_: &Block) -> bool { true }
for _ in 0..increments as usize {
pos.0 += pos_delta / increments;
const MAX_ATTEMPTS: usize = 16;
// While the player is colliding with the terrain...
while collision_with(pos.0, &terrain, block_true, near_iter.clone(), radius, z_range.clone())
&& attempts < MAX_ATTEMPTS
{
// Calculate the player's AABB
let player_aabb = Aabb {
min: pos.0 + Vec3::new(-radius, -radius, z_min),
max: pos.0 + Vec3::new(radius, radius, z_max),
};
// Determine the block that we are colliding with most (based on minimum
// collision axis)
let (_block_pos, block_aabb, block_height) = near_iter
.clone()
// Calculate the block's position in world space
.map(|(i, j, k)| pos.0.map(|e| e.floor() as i32) + Vec3::new(i, j, k))
// Make sure the block is actually solid
.filter_map(|block_pos| {
if let Some(block) = terrain
.get(block_pos)
.ok()
.filter(|block| block.is_solid())
{
// Calculate block AABB
Some((
block_pos,
Aabb {
min: block_pos.map(|e| e as f32),
max: block_pos.map(|e| e as f32) + Vec3::new(1.0, 1.0, block.solid_height()),
},
block.solid_height(),
))
} else {
None
}
})
// Determine whether the block's AABB collides with the player's AABB
.filter(|(_, block_aabb, _)| block_aabb.collides_with_aabb(player_aabb))
// Find the maximum of the minimum collision axes (this bit is weird, trust me that it works)
.min_by_key(|(_, block_aabb, _)| {
((block_aabb.center() - player_aabb.center() - Vec3::unit_z() * 0.5)
.map(|e| e.abs())
.sum()
* 1_000_000.0) as i32
})
.expect("Collision detected, but no colliding blocks found!");
// Find the intrusion vector of the collision
let dir = player_aabb.collision_vector_with_aabb(block_aabb);
// Determine an appropriate resolution vector (i.e: the minimum distance
// needed to push out of the block)
let max_axis = dir.map(|e| e.abs()).reduce_partial_min();
let resolve_dir = -dir.map(|e| {
if e.abs().to_bits() == max_axis.to_bits() {
e
} else {
0.0
}
});
// When the resolution direction is pointing upwards, we must be on the
// ground
if resolve_dir.z > 0.0 && vel.0.z <= 0.0 {
on_ground = true;
if !was_on_ground {
land_on_grounds.push((entity, *vel));
}
} else if resolve_dir.z < 0.0 && vel.0.z >= 0.0 {
on_ceiling = true;
}
// When the resolution direction is non-vertical, we must be colliding
// with a wall If the space above is free...
if !collision_with(Vec3::new(pos.0.x, pos.0.y, (pos.0.z + 0.1).ceil()), &terrain, block_true, near_iter.clone(), radius, z_range.clone())
// ...and we're being pushed out horizontally...
&& resolve_dir.z == 0.0
// ...and the vertical resolution direction is sufficiently great...
&& -dir.z > 0.1
// ...and we're falling/standing OR there is a block *directly* beneath our current origin (note: not hitbox)...
&& (vel.0.z <= 0.0 || terrain
.get((pos.0 - Vec3::unit_z() * 0.1).map(|e| e.floor() as i32))
.map(|block| block.is_solid())
.unwrap_or(false))
// ...and there is a collision with a block beneath our current hitbox...
&& collision_with(
pos.0 + resolve_dir - Vec3::unit_z() * 1.05,
&terrain,
block_true,
near_iter.clone(),
radius,
z_range.clone(),
)
{
// ...block-hop!
pos.0.z = (pos.0.z + 0.1).floor() + block_height;
vel.0.z = 0.0;
on_ground = true;
break;
} else {
// Correct the velocity
vel.0 = vel.0.map2(resolve_dir, |e, d| {
if d * e.signum() < 0.0 { 0.0 } else { e }
});
pos_delta *= resolve_dir.map(|e| if e != 0.0 { 0.0 } else { 1.0 });
}
// Resolve the collision normally
pos.0 += resolve_dir;
attempts += 1;
}
if attempts == MAX_ATTEMPTS {
vel.0 = Vec3::zero();
pos.0 = old_pos;
break;
}
}
if on_ceiling {
physics_state.on_ceiling = true;
}
if on_ground {
physics_state.on_ground = true;
// If the space below us is free, then "snap" to the ground
} else if collision_with(
pos.0 - Vec3::unit_z() * 1.05,
&terrain,
block_true,
near_iter.clone(),
radius,
z_range.clone(),
) && vel.0.z < 0.0
&& vel.0.z > -1.5
&& was_on_ground
&& !collision_with(
pos.0 - Vec3::unit_z() * 0.05,
&terrain,
|block| block.solid_height() >= (pos.0.z - 0.05).rem_euclid(1.0),
near_iter.clone(),
radius,
z_range.clone(),
)
{
let snap_height = terrain
.get(
Vec3::new(pos.0.x, pos.0.y, pos.0.z - 0.05)
.map(|e| e.floor() as i32),
)
.ok()
.filter(|block| block.is_solid())
.map(|block| block.solid_height())
.unwrap_or(0.0);
pos.0.z = (pos.0.z - 0.05).floor() + snap_height;
physics_state.on_ground = true;
}
let dirs = [
Vec3::unit_x(),
Vec3::unit_y(),
-Vec3::unit_x(),
-Vec3::unit_y(),
];
if let (wall_dir, true) =
dirs.iter().fold((Vec3::zero(), false), |(a, hit), dir| {
if collision_with(
pos.0 + *dir * 0.01,
&terrain,
block_true,
near_iter.clone(),
radius,
z_range.clone(),
) {
(a + dir, true)
} else {
(a, hit)
}
})
{
physics_state.on_wall = Some(wall_dir);
} else {
physics_state.on_wall = None;
}
// Figure out if we're in water
physics_state.in_liquid = collision_iter(
pos.0,
&terrain,
&|block| block.is_liquid(),
// The liquid part of a liquid block always extends 1 block high.
&|_block| 1.0,
near_iter.clone(),
radius,
z_min..z_max,
)
.max_by_key(|block_aabb| (block_aabb.max.z * 100.0) as i32)
.map(|block_aabb| block_aabb.max.z - pos.0.z);
},
Collider::Point => {
let (dist, block) = terrain.ray(pos.0, pos.0 + pos_delta)
.until(|block: &Block| block.is_filled())
.ignore_error().cast();
pos.0 += pos_delta.try_normalized().unwrap_or(Vec3::zero()) * dist;
// Can't fail since we do ignore_error above
if block.unwrap().is_some() {
let block_center = pos.0.map(|e| e.floor()) + 0.5;
let block_rpos = (pos.0 - block_center)
.try_normalized()
.unwrap_or(Vec3::zero());
// See whether we're on the top/bottom of a block, or the side
if block_rpos.z.abs()
> block_rpos.xy().map(|e| e.abs()).reduce_partial_max()
{
if block_rpos.z > 0.0 {
physics_state.on_ground = true;
} else {
physics_state.on_ceiling = true;
}
vel.0.z = 0.0;
} else {
physics_state.on_wall =
Some(if block_rpos.x.abs() > block_rpos.y.abs() {
vel.0.x = 0.0;
Vec3::unit_x() * -block_rpos.x.signum()
} else {
vel.0.y = 0.0;
Vec3::unit_y() * -block_rpos.y.signum()
});
}
}
physics_state.in_liquid = terrain.get(pos.0.map(|e| e.floor() as i32))
.ok()
.and_then(|vox| vox.is_liquid().then_some(1.0));
},
}
land_on_grounds
}).reduce(Vec::new, |mut land_on_grounds_a, mut land_on_grounds_b| {
land_on_grounds_a.append(&mut land_on_grounds_b);
land_on_grounds_a
});
drop(guard);
land_on_grounds.into_iter().for_each(|(entity, vel)| {
event_emitter.emit(ServerEvent::LandOnGround { entity, vel: vel.0 });
});
sys_metrics.phys_ns.store(
start_time.elapsed().as_nanos() as u64,
std::sync::atomic::Ordering::Relaxed,
);
}
}