venuss 0.0.1

Venus celestial simulation crate for the MilkyWay SolarSystem workspace
Documentation 
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pub fn maxwell_montes_summit_m() -> f64 {
    11_000.0
}
pub fn deep_basin_m() -> f64 {
    -2_500.0
}

pub fn venus_elevation(lat_deg: f64, lon_deg: f64) -> f64 {
    let lat = lat_deg.to_radians();
    let lon = lon_deg.to_radians();
    let aphrodite = 3000.0 * (-(lat * lat + (lon - 2.0).powi(2)) / 0.5).exp();
    let ishtar = 5000.0 * (-((lat - 1.2).powi(2) + (lon + 1.0).powi(2)) / 0.2).exp();
    aphrodite + ishtar
}

pub struct Heightmap {
    pub data: Vec<f64>,
    pub width: usize,
    pub height: usize,
}

impl Heightmap {
    pub fn generate(width: usize, height: usize) -> Self {
        let mut data = vec![0.0; width * height];
        for j in 0..height {
            let lat = 90.0 - (j as f64 / height as f64) * 180.0;
            for i in 0..width {
                let lon = (i as f64 / width as f64) * 360.0 - 180.0;
                data[j * width + i] = venus_elevation(lat, lon);
            }
        }
        Self {
            data,
            width,
            height,
        }
    }

    pub fn sample(&self, lat_deg: f64, lon_deg: f64) -> f64 {
        let u = ((lon_deg + 180.0) / 360.0).clamp(0.0, 1.0);
        let v = ((90.0 - lat_deg) / 180.0).clamp(0.0, 1.0);
        let x = u * (self.width - 1) as f64;
        let y = v * (self.height - 1) as f64;
        let ix = (x as usize).min(self.width - 2);
        let iy = (y as usize).min(self.height - 2);
        let fx = x - ix as f64;
        let fy = y - iy as f64;
        let v00 = self.data[iy * self.width + ix];
        let v10 = self.data[iy * self.width + ix + 1];
        let v01 = self.data[(iy + 1) * self.width + ix];
        let v11 = self.data[(iy + 1) * self.width + ix + 1];
        v00 * (1.0 - fx) * (1.0 - fy)
            + v10 * fx * (1.0 - fy)
            + v01 * (1.0 - fx) * fy
            + v11 * fx * fy
    }
}