77 lines
2.4 KiB
Rust
77 lines
2.4 KiB
Rust
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use eframe::egui;
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pub trait MapProjection: Send + Sync {
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fn project(&self, lon: f64, lat: f64, rect: egui::Rect) -> egui::Pos2;
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fn unproject(&self, pos: egui::Pos2, rect: egui::Rect) -> (f64, f64);
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fn name(&self) -> &'static str;
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}
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pub struct Equirectangular;
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impl MapProjection for Equirectangular {
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fn project(&self, lon: f64, lat: f64, rect: egui::Rect) -> egui::Pos2 {
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egui::pos2(
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rect.left() + ((lon + 180.0) / 360.0) as f32 * rect.width(),
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rect.top() + ((90.0 - lat) / 180.0) as f32 * rect.height(),
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)
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}
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fn unproject(&self, pos: egui::Pos2, rect: egui::Rect) -> (f64, f64) {
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let lon = (pos.x - rect.left()) as f64 / rect.width() as f64 * 360.0 - 180.0;
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let lat = 90.0 - (pos.y - rect.top()) as f64 / rect.height() as f64 * 180.0;
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(lon, lat)
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}
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fn name(&self) -> &'static str {
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"Equirectangular"
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn unit_rect() -> egui::Rect {
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egui::Rect::from_min_size(egui::Pos2::ZERO, egui::vec2(360.0, 180.0))
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}
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#[test]
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fn roundtrip_center() {
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let proj = Equirectangular;
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let r = unit_rect();
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let pos = proj.project(0.0, 0.0, r);
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let (lon, lat) = proj.unproject(pos, r);
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assert!((lon).abs() < 1e-4);
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assert!((lat).abs() < 1e-4);
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}
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#[test]
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fn roundtrip_corners() {
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let proj = Equirectangular;
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let r = unit_rect();
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for (lon, lat) in [(-180.0_f64, 90.0_f64), (180.0, -90.0), (-180.0, -90.0), (180.0, 90.0)] {
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let pos = proj.project(lon, lat, r);
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let (lon2, lat2) = proj.unproject(pos, r);
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assert!((lon - lon2).abs() < 1e-4, "lon {lon} → {lon2}");
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assert!((lat - lat2).abs() < 1e-4, "lat {lat} → {lat2}");
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}
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}
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#[test]
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fn project_prime_meridian_equator() {
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let proj = Equirectangular;
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let r = unit_rect();
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let pos = proj.project(0.0, 0.0, r);
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assert!((pos.x - 180.0).abs() < 1e-3, "x={}", pos.x);
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assert!((pos.y - 90.0).abs() < 1e-3, "y={}", pos.y);
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}
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#[test]
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fn rect_scaling() {
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let proj = Equirectangular;
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let r = egui::Rect::from_min_size(egui::pos2(10.0, 20.0), egui::vec2(720.0, 360.0));
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let pos = proj.project(0.0, 0.0, r);
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assert!((pos.x - 370.0).abs() < 1e-3, "x={}", pos.x);
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assert!((pos.y - 200.0).abs() < 1e-3, "y={}", pos.y);
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}
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}
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