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Add a function for integrating forces

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This commit is contained in:
Louis Pearson 2019-06-04 09:42:31 -06:00
parent c7a2ecd1f2
commit 82aabf242a
1 changed files with 25 additions and 10 deletions
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35
common/src/sys/phys.rs
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@ -15,6 +15,27 @@ pub struct Sys;
const GRAVITY: f32 = 9.81 * 4.0;
// 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>, damp: f32) -> Vec3<f32> {
lv.z -= (GRAVITY * dt).max(-50.0);
let mut linear_damp = 1.0 - dt * damp;
if linear_damp < 0.0
// reached zero in the given time
{
linear_damp = 0.0;
}
lv *= linear_damp;
lv
}
impl<'a> System<'a> for Sys {
type SystemData = (
ReadExpect<'a, TerrainMap>,
@ -38,16 +59,10 @@ impl<'a> System<'a> for Sys {
.unwrap_or(false)
&& vel.0.z <= 0.0;
// Friction
// Will never make the character go backwards since it is interpolating towards 0
let friction = if on_ground { 0.15 } else { 0.015 };
let mul = 50.0;
let z = vel.0.z;
vel.0 = Vec3::lerp(vel.0, Vec3::new(0.0, 0.0, 0.0), friction * dt.0 * mul);
vel.0.z = z;
// Gravity
vel.0.z = (vel.0.z - GRAVITY * dt.0).max(-50.0);
// Integrate forces
// Friction is assumed to be a constant dependent on location
let friction = 50.0 * if on_ground { 0.15 } else { 0.015 };
vel.0 = integrate_forces(dt.0, vel.0, friction);
// Movement
pos.0 += vel.0 * dt.0;