sagittariusas 0.0.3

Simulation engine for Sagittarius A* — Kerr spacetime, accretion, jets, lensing, and shadow observables
Documentation 
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#[derive(Debug, Clone, Copy, PartialEq)]
pub struct LensingShaderData {
    pub schwarzschild_radius_m: f64,
    pub spin_parameter: f64,
    pub inclination_rad: f64,
    pub observer_distance_m: f64,
}

impl LensingShaderData {
    pub fn sagittarius_a_star() -> Self {
        Self {
            schwarzschild_radius_m: 1.2e10,
            spin_parameter: 0.9,
            inclination_rad: std::f64::consts::FRAC_PI_4,
            observer_distance_m: 2.55e20,
        }
    }

    pub fn einstein_ring_radius_rad(&self) -> f64 {
        (4.0 * 6.674e-11 * 4.15e6 * 1.989e30 / (2.998e8 * 2.998e8 * self.observer_distance_m))
            .sqrt()
    }

    pub fn isco_radius(&self) -> f64 {
        let a = self.spin_parameter;
        if a.abs() < 1e-12 {
            return 3.0 * self.schwarzschild_radius_m;
        }
        let z1 = 1.0
            + (1.0 - a * a).powf(1.0 / 3.0)
                * ((1.0 + a).powf(1.0 / 3.0) + (1.0 - a).powf(1.0 / 3.0));
        let z2 = (3.0 * a * a + z1 * z1).sqrt();
        let r_g = self.schwarzschild_radius_m / 2.0;
        r_g * (3.0 + z2 - ((3.0 - z1) * (3.0 + z1 + 2.0 * z2)).sqrt())
    }

    pub fn photon_sphere_radius(&self) -> f64 {
        1.5 * self.schwarzschild_radius_m
    }

    pub fn gravitational_redshift(&self, emission_radius_m: f64) -> f64 {
        let rs = self.schwarzschild_radius_m;
        1.0 / (1.0 - rs / emission_radius_m).sqrt() - 1.0
    }
}

#[derive(Debug, Clone, Copy, PartialEq)]
pub struct AccretionDiskShaderData {
    pub inner_radius_isco: f32,
    pub outer_radius_isco: f32,
    pub rotation_speed: f32,
    pub turbulence: f32,
}

impl AccretionDiskShaderData {
    pub fn standard_thin_disk() -> Self {
        Self {
            inner_radius_isco: 1.0,
            outer_radius_isco: 20.0,
            rotation_speed: 1.0,
            turbulence: 0.1,
        }
    }

    pub fn thick_advective() -> Self {
        Self {
            inner_radius_isco: 1.0,
            outer_radius_isco: 50.0,
            rotation_speed: 0.7,
            turbulence: 0.5,
        }
    }
}