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got vel to be constant, NOICE

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This commit is contained in:
Marcel Märtens 2022-06-07 19:46:50 +02:00
parent 1b5db351d2
commit aa68bd6c9f
1 changed files with 21 additions and 16 deletions
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37
common/systems/tests/phys/basic.rs
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@ -5,6 +5,7 @@ use specs::WorldExt;
use std::error::Error;
use utils::{DT, DT_F64, EPSILON};
use vek::{approx, Vec2, Vec3};
use common::states::utils::unwrap_tool_data;
use veloren_common_systems::add_local_systems;
#[test]
@ -317,32 +318,36 @@ fn physics_theory() -> Result<(), Box<dyn Error>> {
https://sciencing.com/calculate-force-friction-6454395.html
https://www.leifiphysik.de/mechanik/reibung-und-fortbewegung
*/
let mass = 80.0;
let gravity = 9.81;
let f_n = mass * gravity;
let mass = 1.0;
let air_friction_co = 1.1_f64;
let air_friction_area = 1.0_f64;
let air_density = 1.225_f64;
let c = air_friction_co * air_friction_area * 0.5 * air_density * mass;
//let acc = accel_force / mass * move_dir;
let acc = 9.0_f64; // btw: cant accelerate faster than gravity on foot
let old_vel = vel;
let total_force = 2.0_f64 * mass;
let rolling_friction_co = 0.0001;
let rolling_friction_force = rolling_friction_co * f_n;
let air_friction_co = 0.0000_f64;
let air_friction_force = air_friction_co;
let accel_force = total_force - rolling_friction_force - air_friction_force;
let acc = accel_force / mass * move_dir;
// controller
let vel = vel + acc * dt;
// I know what you think, wtf, yep: https://math.stackexchange.com/questions/1929436/line-integral-of-force-of-air-resistanc
// basically an integral of the air resistance formula which scales with v^2 transformed with an ODE.
let vel = (mass * acc / c).sqrt() * ( ( (c / acc / mass ).sqrt() * old_vel ).atanh() + (c * acc / mass).sqrt() * 0.1* dt ).tanh();
//physics
let distance = vel * dt - 0.5 * acc * dt * dt;
let acc2 = (vel - old_vel) / dt;
let distance = vel * dt;// 0.5 * vel * dt - 0.5 * acc2 * dt * dt;
let pos = pos + distance;
if ((i+1) as f64 *dt * 10.0).round() as i64 % 2 == 0 {
println!("[{:0>2.1}]: move_dir: {:4.1}, acc: {:4.4}, vel: {:4.4}, pos: {:4.4}, accel_force: {:4.4}", (i+1) as f64 *dt, move_dir, acc, vel, pos, accel_force);
}
//if ((i+1) as f64 *dt * 10.0).round() as i64 % 2 == 0 {
println!("[{:0>2.1}]: move_dir: {:4.1}, acc: {:4.4}, vel: {:4.4}, pos: {:4.4}, c: {:4.4}", (i+1) as f64 *dt, move_dir, acc, vel, pos, c);
//}
(acc, vel, pos)
};