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Revert "Exponential interpolation for linear damping"

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This reverts commit 94b9f50efa.
This commit is contained in:
Andrew Pritchard 2019-09-05 18:24:22 +08:00
parent 94b9f50efa
commit 8b9a3ae1df
1 changed files with 26 additions and 39 deletions
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65
common/src/sys/phys.rs
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@ -11,14 +11,8 @@ use {
};
const GRAVITY: f32 = 9.81 * 4.0;
// 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 frction
// 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.
const FRIC_GROUND: f32 = 0.125;
const FRIC_AIR: f32 = 0.0125;
const FRIC_GROUND: f32 = 0.15;
const FRIC_AIR: f32 = 0.015;
// Integrates forces, calculates the new velocity based off of the old velocity
// dt = delta time
@ -26,16 +20,10 @@ const FRIC_AIR: f32 = 0.0125;
// 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 = if damp < 1.0 {
(1.0 - damp).powf(dt * 60.0)
} else {
0.0
};
lv.z = (lv.z - grav * dt).max(-50.0);
let linear_damp = (1.0 - dt * damp).max(0.0);
lv * linear_damp
}
@ -73,7 +61,7 @@ impl<'a> System<'a> for Sys {
let mut event_emitter = event_bus.emitter();
// Apply movement inputs
for (entity, scale, _b, mut pos, mut vel, _ori) in (
for (entity, scale, b, mut pos, mut vel, mut ori) in (
&entities,
scales.maybe(),
&bodies,
@ -86,6 +74,16 @@ impl<'a> System<'a> for Sys {
let mut physics_state = physics_states.get(entity).cloned().unwrap_or_default();
let scale = scale.map(|s| s.0).unwrap_or(1.0);
// Integrate forces
// Friction is assumed to be a constant dependent on location
let friction = 50.0
* if physics_state.on_ground {
FRIC_GROUND
} else {
FRIC_AIR
};
vel.0 = integrate_forces(dt.0, vel.0, GRAVITY, friction);
// Basic collision with terrain
let player_rad = 0.3 * scale; // half-width of the player's AABB
let player_height = 1.5 * scale;
@ -99,27 +97,6 @@ impl<'a> System<'a> for Sys {
.flatten()
.flatten();
let old_vel = vel.clone();
// Integrate forces
// Friction is assumed to be a constant dependent on location
let friction = if physics_state.on_ground {
FRIC_GROUND
} else {
FRIC_AIR
};
vel.0 = integrate_forces(dt.0, vel.0, GRAVITY, friction);
// Don't move if we're not in a loaded chunk
let pos_delta = if terrain
.get_key(terrain.pos_key(pos.0.map(|e| e.floor() as i32)))
.is_some()
{
// this is an approximation that allows
(vel.0 + old_vel.0 * 4.0) * dt.0 * 0.2
} else {
Vec3::zero()
};
// Function for determining whether the player at a specific position collides with the ground
let collision_with = |pos: Vec3<f32>, near_iter| {
for (i, j, k) in near_iter {
@ -153,6 +130,16 @@ impl<'a> System<'a> for Sys {
let mut on_ground = false;
let mut attempts = 0; // Don't loop infinitely here
// Don't move if we're not in a loaded chunk
let pos_delta = if terrain
.get_key(terrain.pos_key(pos.0.map(|e| e.floor() as i32)))
.is_some()
{
vel.0 * dt.0
} else {
Vec3::zero()
};
// Don't jump too far at once
let increments = (pos_delta.map(|e| e.abs()).reduce_partial_max() / 0.3)
.ceil()