Earth and moon eclipse

crates/resolved-cli/Cargo.toml

@@ -27,3 +27,7 @@ serde = { version = "1.0", features = ["derive"] }
 toml = "1.1"
 image = { version = "0.25", default-features = false, features = ["png"] }
 hifitime = { version = "4.3", optional = true }
+
+[dev-dependencies]
+# JPEG too, so the tests can write a small stand-in for the Blue Marble images.
+image = { version = "0.25", default-features = false, features = ["png", "jpeg"] }

crates/resolved-cli/src/main.rs

@@ -45,8 +45,8 @@ struct RenderArgs {
     /// An 8-bit sRGB PNG for viewing: bias subtracted, saturation as white.
     #[arg(long)]
     preview: Option<PathBuf>,
-    /// Lighting fidelity tier: L0, or L1 (adds Earth's surface, shadows on targets and
-    /// light from Earth and the Moon; needs Blue Marble data).
+    /// Lighting fidelity tier: L0, or L1 (adds Earth's surface, shadows on targets,
+    /// light from Earth and the Moon, and eclipses on them; needs Blue Marble data).
     #[arg(long, default_value = "L0")]
     lighting: LightingTier,
     /// Camera fidelity tier: C0.

crates/resolved-cli/tests/cli.rs

@@ -27,8 +27,37 @@ fn resolved(args: &[&str]) -> std::process::Output {
 /// Renders `scene` on `adapter` to a 16-bit PNG and returns its pixels as DN (the
 /// file holds 12-bit DN shifted up by 4).
 fn render(scene: &str, adapter: &str) -> image::ImageBuffer<image::Rgb<u16>, Vec<u16>> {
+    render_at(scene, adapter, "L0")
+}
+
+/// A data directory whose Earth images are small and uniformly gray, for tests at
+/// lighting L1 that do not need Blue Marble: loading the real 16384 x 8192 images takes
+/// seconds in a debug build, and they are only there once fetched.
+fn gray_earth() -> PathBuf {
+    static DIR: std::sync::OnceLock<PathBuf> = std::sync::OnceLock::new();
+    DIR.get_or_init(|| {
+        let dir = out_dir().join("gray-data");
+        std::fs::create_dir_all(dir.join("earth")).unwrap();
+        let image = image::RgbImage::from_pixel(64, 32, image::Rgb([128; 3]));
+        for month in 1..=12 {
+            image
+                .save(dir.join(format!("earth/bmng-2004-{month:02}.jpg")))
+                .unwrap();
+        }
+        dir
+    })
+    .clone()
+}
+
+/// [`render`] at lighting tier `lighting`, with Earth's images from [`gray_earth`].
+fn render_at(
+    scene: &str,
+    adapter: &str,
+    lighting: &str,
+) -> image::ImageBuffer<image::Rgb<u16>, Vec<u16>> {
+    let data = gray_earth();
     let out = out_dir().join(format!(
-        "{}-{adapter}.png",
+        "{}-{lighting}-{adapter}.png",
         Path::new(scene).file_stem().unwrap().to_str().unwrap()
     ));
     let preview = out.with_extension("preview.png");
@@ -38,6 +67,10 @@ fn render(scene: &str, adapter: &str) -> image::ImageBuffer<image::Rgb<u16>, Vec
         scene,
         "--adapter",
         adapter,
+        "--lighting",
+        lighting,
+        "--data",
+        data.to_str().unwrap(),
         "--out",
         out.to_str().unwrap(),
         "--preview",
@@ -92,6 +125,45 @@ fn epoch_scene_renders() {
     assert_eq!(frame.get_pixel(0, 0).0, [64; 3]);
 }
 
+#[cfg(feature = "astrokit")]
+#[test]
+fn lunar_eclipse_darkens_the_moon() {
+    // Mid-totality: at L1 the whole Moon is in Earth's umbra and reads the bias. At L0
+    // there are no eclipses on the bodies and it is a full Moon.
+    let scene = "examples/scenes/lunar-eclipse.toml";
+    let l0 = render_at(scene, "gpu", "L0");
+    let l1 = render_at(scene, "gpu", "L1");
+    assert!(
+        l0.get_pixel(960, 540).0.iter().all(|&v| v > 150),
+        "{:?}",
+        l0.get_pixel(960, 540)
+    );
+    assert!(
+        l1.pixels().all(|p| p.0 == [64; 3]),
+        "every pixel at the bias"
+    );
+}
+
+#[cfg(feature = "astrokit")]
+#[test]
+fn solar_eclipse_puts_the_umbra_at_greatest_eclipse() {
+    // The camera looks straight down at the point of greatest eclipse from NASA's
+    // bulletin (65.2 N 25.2 W, 17:46 UTC): at L1 it is in the Moon's umbra and reads the
+    // bias, and the image corner, about 3500 km away in the penumbra, is brighter. At L0
+    // the center is lit.
+    let scene = "examples/scenes/solar-eclipse.toml";
+    let l0 = render_at(scene, "gpu", "L0");
+    let l1 = render_at(scene, "gpu", "L1");
+    assert!(
+        l0.get_pixel(960, 540).0.iter().all(|&v| v > 100),
+        "{:?}",
+        l0.get_pixel(960, 540)
+    );
+    assert_eq!(l1.get_pixel(960, 540).0, [64; 3]);
+    let corner = l1.get_pixel(40, 1040).0;
+    assert!(corner.iter().all(|&v| v > 70), "{corner:?}");
+}
+
 #[test]
 fn errors_are_reported() {
     let missing = resolved(&["render", "--scene", "no/such.toml", "--preview", "x.png"]);