CLI, along with several examples, plus model downloading

readme.md

@@ -61,6 +61,35 @@ assert!(frame.dn_at(960, 540, 1) > 1000);
 # }
 ```
 
+## Command line
+
+`resolved render` renders a scene described in TOML: camera overrides, the
+observer, Sun and Moon positions (or an epoch, with the `astrokit` feature) and
+targets with their models. `examples/scenes/` has commented examples:
+`boxwing.toml` and `boxwing-epoch.toml` use a small generated model that is
+in the repository, and the rest use NASA spacecraft models (Landsat 8,
+ICESat-2, OSTM/Jason-2, an SSL-1300 and ACE) that `scripts/fetch-models.sh`
+downloads into `examples/models/nasa/`. That script needs Node (for `npx`),
+because most NASA models are Draco-compressed and are decoded on the way in.
+
+```sh
+cargo run --release -p resolved-cli -- render \
+    --scene examples/scenes/boxwing.toml \
+    --out frame.png --preview preview.png --timings 50
+```
+
+- `--out` writes raw DN as a 16-bit PNG, shifted up to fill 16 bits as
+  cameras usually store them: a 12-bit DN is the stored value divided by 16.
+  It is linear, so it looks dark next to the preview.
+- `--preview` writes an 8-bit sRGB image for looking at, with the bias as
+  black and saturation as white.
+- `--timings N` renders N frames and reports setup and per-frame times.
+- `--adapter` takes `auto`, `gpu`, `cpu` or part of an adapter's name;
+  `resolved adapters` lists them.
+- `--kernels DIR` says where astrokit's kernels are, for scenes given by
+  epoch. Without it the CLI tries `ASTROKIT_KERNELS`, then `data/kernels`,
+  then the sibling `../astrokit` checkout it was built against.
+
 ## Features
 
 - `astrokit`: build a `Scene` from an epoch with
@@ -73,7 +102,8 @@ assert!(frame.dn_at(960, 540, 1) > 1000);
 ## Status
 
 M1 in progress: the library renders Earth, Moon, Sun and targets to DN
-through `Renderer`; the CLI and benchmarks are still to come. The work is
+through `Renderer`, and the CLI renders scene files; benchmarks are still to
+come. The work is
 tracked as Gitea milestones, each split into one issue per change:
 
 | Milestone | Scope |
@@ -96,6 +126,10 @@ tracked as Gitea milestones, each split into one issue per change:
 - `crates/resolved`: the library.
 - `crates/resolved-cli`: the `resolved` command, for rendering without writing
   a host program.
+- `examples/`: scene files and the box-wing model
+  (`scripts/make-example-model.py` regenerates it). The NASA scenes are
+  generated by `scripts/make-example-scenes.py`.
+- `scripts/`: generators for compiled-in data and examples.
 - `docs/optics.md`: the optics and radiometry the renderer models, explained
   for readers without an optics background.