proj4rs 0.1.4

Rust adaptation of Proj4
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170

//!
//! Swiss Oblique Mercator
//!
//! ref: <https://proj.org/operations/projections/somerc.html>
//!
//! somerc: "Swiss. Obl. Mercator" "\n\tCyl, Ell\n\tFor CH1903";
//!
use crate::errors::{Error, Result};
use crate::math::{
    aasin,
    consts::{EPS_10, FRAC_PI_2, FRAC_PI_4},
};
use crate::parameters::ParamList;
use crate::proj::ProjData;

// Projection stub
super::projection! { somerc }

#[derive(Debug, Clone)]
pub(crate) struct Projection {
    e: f64,
    rone_es: f64,
    k: f64,
    c: f64,
    hlf_e: f64,
    k_r: f64,
    cosp0: f64,
    sinp0: f64,
}

#[allow(non_snake_case)]
impl Projection {
    pub fn somerc(p: &mut ProjData, _: &ParamList) -> Result<Self> {
        let el = &p.ellps;
        let hlf_e = 0.5 * el.e;

        let (sinphi, cosphi) = p.phi0.sin_cos();

        let cp = cosphi * cosphi;
        let c = (1. + el.es * cp * cp * el.rone_es).sqrt();
        let sinp0 = sinphi / c;
        let phip0 = aasin(sinp0)?;
        let cosp0 = phip0.cos();
        let sp = sinphi * el.e;
        let k = (FRAC_PI_4 + 0.5 * phip0).tan().ln()
            - c * ((FRAC_PI_4 + 0.5 * p.phi0).tan().ln() - hlf_e * ((1. + sp) / (1. - sp)).ln());
        let k_r = p.k0 * el.one_es.sqrt() / (1. - sp * sp);
        Ok(Self {
            e: el.e,
            rone_es: el.rone_es,
            k,
            c,
            hlf_e,
            k_r,
            cosp0,
            sinp0,
        })
    }

    #[inline(always)]
    pub fn forward(&self, lam: f64, phi: f64, z: f64) -> Result<(f64, f64, f64)> {
        let sp = self.e * phi.sin();
        let phip = 2.
            * ((self.c
                * ((FRAC_PI_4 + 0.5 * phi).tan().ln()
                    - self.hlf_e * ((1. + sp) / (1. - sp)).ln())
                + self.k)
                .exp())
            .atan()
            - FRAC_PI_2;

        let lamp = self.c * lam;
        let cp = phip.cos();
        let phipp = aasin(self.cosp0 * phip.sin() - self.sinp0 * cp * lamp.cos())?;
        let lampp = aasin(cp * lamp.sin() / phipp.cos())?;

        Ok((
            self.k_r * lampp,
            self.k_r * (FRAC_PI_4 + 0.5 * phipp).tan().ln(),
            z,
        ))
    }

    #[inline(always)]
    pub fn inverse(&self, x: f64, y: f64, z: f64) -> Result<(f64, f64, f64)> {
        const NITER: isize = 6;

        let phipp = 2. * (((y / self.k_r).exp()).atan() - FRAC_PI_4);
        let lampp = x / self.k_r;
        let cp = phipp.cos();
        let mut phip = aasin(self.cosp0 * phipp.sin() + self.sinp0 * cp * lampp.cos())?;
        let lamp = aasin(cp * lampp.sin() / phip.cos())?;
        let con = (self.k - (FRAC_PI_4 + 0.5 * phip).tan().ln()) / self.c;

        let mut i = NITER;
        while i > 0 {
            let esp = self.e * phip.sin();
            let delp = (con + (FRAC_PI_4 + 0.5 * phip).tan().ln()
                - self.hlf_e * ((1. + esp) / (1. - esp)).ln())
                * (1. - esp * esp)
                * phip.cos()
                * self.rone_es;
            phip -= delp;
            if delp.abs() < EPS_10 {
                break;
            }
            i -= 1;
        }
        if i <= 0 {
            Err(Error::ToleranceConditionError)
        } else {
            Ok((lamp / self.c, phip, z))
        }
    }

    pub const fn has_inverse() -> bool {
        true
    }

    pub const fn has_forward() -> bool {
        true
    }
}

#[cfg(test)]
mod tests {
    use crate::math::consts::EPS_10;
    use crate::proj::Proj;
    use crate::tests::utils::{test_proj_forward, test_proj_inverse};

    #[test]
    fn proj_somerc_el() {
        let p = Proj::from_proj_string("+proj=somerc +ellps=GRS80").unwrap();

        println!("{:#?}", p.projection());

        let inputs = [
            ((2., 1., 0.), (222638.98158654713, 110579.96521824898, 0.)),
            ((2., -1., 0.), (222638.98158654713, -110579.96521825089, 0.)),
            ((-2., 1., 0.), (-222638.98158654713, 110579.96521824898, 0.)),
            (
                (-2., -1., 0.),
                (-222638.98158654713, -110579.96521825089, 0.),
            ),
        ];

        test_proj_forward(&p, &inputs, EPS_10);
        test_proj_inverse(&p, &inputs, EPS_10);
    }

    #[test]
    fn proj_somerc_sp() {
        let p = Proj::from_proj_string("+proj=somerc +a=6400000").unwrap();

        println!("{:#?}", p.projection());

        let inputs = [
            ((2., 1., 0.), (223402.14425527418, 111706.74357494408, 0.)),
            ((2., -1., 0.), (223402.14425527418, -111706.74357494518, 0.)),
            ((-2., 1., 0.), (-223402.14425527418, 111706.74357494408, 0.)),
            (
                (-2., -1., 0.),
                (-223402.14425527418, -111706.74357494518, 0.),
            ),
        ];

        test_proj_forward(&p, &inputs, EPS_10);
        test_proj_inverse(&p, &inputs, EPS_10);
    }
}