From 169b9ee2571edfd03376c582c19114f152e39f69 Mon Sep 17 00:00:00 2001 From: yuni Date: Sat, 8 Jun 2024 03:15:25 +0200 Subject: [PATCH] add nature::gravitational_acceleration, incl. test --- src/nature.rs | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/src/nature.rs b/src/nature.rs index 78b9284..360059e 100644 --- a/src/nature.rs +++ b/src/nature.rs @@ -28,9 +28,11 @@ pub const G: f64 = 6.6743015e-11; // Gravitational constant in Nm²/kg² pub const SOL_RADIUS: f64 = 696_300_000.0; pub const JUPITER_RADIUS: f64 = 71_492_000.0; pub const JUPITER_RING_RADIUS: f64 = 229_000_000.0; +pub const EARTH_RADIUS: f64 = 6_371_000.0; pub const SOL_MASS: f64 = 1.9885e30; pub const JUPITER_MASS: f64 = 1.8982e27; +pub const EARTH_MASS: f64 = 5.972168e24; // Each star's values: (x, y, z, magnitude, color index, distance, name) pub const STARS: &[(f32, f32, f32, f32, f32, f32, &str)] = &include!("data/stars.in"); @@ -180,6 +182,22 @@ pub fn orbital_velocity(coords: Vec3, mass: f64) -> Vec3 { return perpendicular * speed; } +/// Calculates the acceleration towards a mass in m/s +pub fn gravitational_acceleration(coords: Vec3, mass: f64) -> Vec3 { + let r_squared = coords.length_squared() as f64; + let acceleration_magnitude = G * mass / r_squared; + return -acceleration_magnitude as f32 * (coords / r_squared.sqrt() as f32); +} + +#[test] +fn test_gravitational_acceleration() { + let coords = Vec3::new(EARTH_RADIUS as f32, 0.0, 0.0); + let mass = EARTH_MASS; + let g = gravitational_acceleration(coords, mass); + let g_rounded = (g * 10.0).round() / 10.0; + assert_eq!(g_rounded, Vec3::new(-9.8, 0.0, 0.0)); +} + pub fn phase_dist_to_coords(phase_radians: f64, distance: f64) -> DVec3 { return DVec3::new( distance * phase_radians.cos(),