cli, mcp: snapshot --section and --field; headless MCP screenshots on the GPU

--section x|y|z[=VALUE] hides the elements on the camera's side of a plane
(at the mesh's middle by default) so the element faces inside show;
--field contours a nodal field of the solved step (results.contour). The
MCP server's headless screenshot draws with the viewport's pipeline on the
shared device and its reply, like snapshot's, names the renderer.

Refs #422

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
This commit is contained in:
jyvikoandClaude Opus 5.5 authored and Irakli Kourtis committed 2026-10-15 20:50:40 -04:00
1 parent c9163e98ad
commit 390ddcd6cc
10 files changed
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+12 -2
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@@ -1,6 +1,6 @@
//! fieldcraft-cli commands
//! fieldcraft-cli run <script.json>
//! fieldcraft-cli snapshot <script.json> --out shot.png [--view iso|x|y|z|front|…] [--size WxH]
//! fieldcraft-cli snapshot <script.json> --out shot.png [--view V] [--size WxH] [--section x|y|z[=V]] [--field F]
//! fieldcraft-cli features
//! fieldcraft-cli mcp [--connect ADDR | --headless] [--automation-read-root DIR] [--automation-write-root DIR]
//! fieldcraft-cli crashes [list [--json] | show <id> | replay <id> | dir | clear [<id>]]
@@ -26,11 +26,15 @@ usage:
fieldcraft-cli run <script.json> run a script (a JSON array of {\"command\", \"params\"})
and print the model summary
fieldcraft-cli snapshot <script.json> --out FILE.png [--view V] [--size WxH]
[--section x|y|z[=VALUE]] [--field FIELD]
run a script and draw the model to a PNG with no
window: the viewport's GPU pipeline on a hardware or
software GPU, else the CPU rasterizer (FIELDCRAFT_GPU=
auto|hardware|software|cpu); V: iso (default), x, y, z,
front, back, left, right, top, bottom; size 1280x800
front, back, left, right, top, bottom; size 1280x800;
--section hides the elements beyond a plane (at the
mesh's middle, or VALUE); --field contours a nodal
field of the solved step (results.contour)
fieldcraft-cli features print docs/features.md (every capability, ready or
coming soon) from the capability catalogue
fieldcraft-cli mcp [options] serve the Model Context Protocol on stdin/stdout
@@ -144,6 +148,12 @@ fn mcp(args: &[String]) -> Result<(), String> {
server.serve(std::io::stdin().lock(), std::io::stdout().lock()).map_err(|e| format!("mcp: {e}"))
}
/// The JSON report of a picture: what drew it and what it shows (the MCP `screenshot` reply's
/// fields).
pub fn picture_report(r: &fieldcraft_gpu::Renderer, shown: &fieldcraft_engine::view::Shown) -> serde_json::Value {
fieldcraft_mcp::picture_report(r, shown)
}
/// The session after running the script at `path`.
fn session_of(path: &str) -> Result<Session, String> {
let size = std::fs::metadata(path).map_err(|e| format!("{path}: {e}"))?.len();
+70 -45
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@@ -4,20 +4,25 @@
//! (lavapipe, llvmpipe, WARP), and by the CPU rasterizer as the last tier (`FIELDCRAFT_GPU`,
//! [`fieldcraft_gpu::select`]).
use fieldcraft_engine::view::{self, Palette};
use fieldcraft_gpu::capture::Capturer;
use fieldcraft_engine::view::{self, Palette, Section};
use fieldcraft_gpu::Renderer;
use fieldcraft_gpu::capture::{self, Capturer};
use fieldcraft_gpu::select::Policy;
use fieldcraft_render::{Orientation, StandardView};
/// The picture size when `--size` is not given.
const DEFAULT_SIZE: (u32, u32) = (1280, 800);
#[derive(Debug, PartialEq)]
#[derive(Clone, Debug, PartialEq)]
pub struct Options {
pub script: String,
pub out: String,
pub view: StandardView,
pub size: (u32, u32),
/// A section through the mesh (`--section x|y|z[=VALUE]`).
pub section: Option<Section>,
/// A nodal field contoured on the last solved step (`--field von_mises`).
pub field: Option<String>,
}
/// A view name: a standard view, or the axis looked along (`x`: from the right, `y`: from the
@@ -41,7 +46,7 @@ fn size_of(s: &str) -> Option<(u32, u32)> {
/// The options: the script, then each flag once, as `--flag value` or `--flag=value`.
pub fn options(args: &[String]) -> Result<Options, String> {
let (mut script, mut out, mut view, mut size) = (None, None, None, None);
let (mut script, mut out, mut view, mut size, mut section, mut field) = (None, None, None, None, None, None);
let mut it = args.iter();
while let Some(arg) = it.next() {
if !arg.starts_with("--") {
@@ -71,6 +76,10 @@ pub fn options(args: &[String]) -> Result<Options, String> {
)
})?)
.is_some(),
"--section" => section
.replace(Section::parse(&value).ok_or_else(|| format!("--section: `{value}` is not x, y, z or AXIS=VALUE (x=12.5)"))?)
.is_some(),
"--field" => field.replace(value).is_some(),
other => return Err(format!("snapshot: unknown option `{other}`")),
};
if twice {
@@ -82,50 +91,36 @@ pub fn options(args: &[String]) -> Result<Options, String> {
out: out.ok_or("snapshot needs --out FILE.png")?,
view: view.unwrap_or(StandardView::Iso),
size: size.unwrap_or(DEFAULT_SIZE),
section,
field,
})
}
/// What drew a picture.
#[derive(Debug, PartialEq)]
pub enum Drawn {
Gpu { adapter: String, tier: &'static str, samples: u32 },
Cpu { why: Option<String> },
}
/// The PNG of the session `o` describes, drawn as `policy` says. Under [`Policy::Auto`] a GPU
/// that cannot be opened or fails to draw falls back to the CPU rasterizer (the reason is
/// returned); a strict policy returns the error.
pub fn picture(o: &Options, policy: Policy) -> Result<(Vec<u8>, Drawn), String> {
let session = crate::session_of(&o.script)?;
/// The PNG of the session `o` describes, drawn as `policy` says ([`capture::png`]).
pub fn picture(o: &Options, policy: Policy) -> Result<(Vec<u8>, Renderer, view::Shown), String> {
let mut session = crate::session_of(&o.script)?;
if let Some(field) = &o.field {
session.execute("results.contour", &serde_json::json!({"field": field})).map_err(|e| format!("--field: {e}"))?;
}
let (w, h) = o.size;
let f = view::frame(&session, &Orientation::of(o.view), w as usize, h as usize, &Palette::LIGHT);
let gpu = Capturer::open(policy).and_then(|c| match c {
Some(c) => c.rgba(&f.scene, &[&f.symbols], &f.cam, w, h).map(|px| Some((px, c))),
None => Ok(None),
});
let why = match gpu {
Ok(Some((px, c))) => {
let png = fieldcraft_render::png(w as usize, h as usize, &px).ok_or("the picture could not be encoded")?;
return Ok((png, Drawn::Gpu { adapter: c.adapter.clone(), tier: c.tier.label(), samples: c.samples() }));
}
Ok(None) => (policy == Policy::Auto).then(|| "no GPU adapter".to_string()),
Err(e) if policy == Policy::Auto => Some(e.to_string()),
Err(e) => return Err(e.to_string()),
};
let png = fieldcraft_render::render_layers_png(&f.scene, &[&f.symbols], &f.cam, w as usize, h as usize).map_err(|e| format!("render: {e}"))?;
Ok((png, Drawn::Cpu { why }))
let f = view::frame(&session, &Orientation::of(o.view), w as usize, h as usize, &Palette::LIGHT, o.section);
let capturer = Capturer::open(policy);
let (png, renderer) = capture::png(&capturer, policy, &f.scene, &[&f.symbols], &f.cam, w, h).map_err(|e| e.to_string())?;
Ok((png, renderer, f.shown))
}
pub fn run(args: &[String]) -> Result<(), String> {
let o = options(args)?;
let policy = Policy::from_env().map_err(|e| e.to_string())?;
let (png, drawn) = picture(&o, policy)?;
let (png, renderer, shown) = picture(&o, policy)?;
std::fs::write(&o.out, &png).map_err(|e| format!("{}: {e}", o.out))?;
let renderer = match &drawn {
Drawn::Gpu { adapter, tier, samples } => serde_json::json!({"kind": tier, "adapter": adapter, "msaa": samples}),
Drawn::Cpu { why } => serde_json::json!({"kind": "CPU rasterizer", "why": why}),
};
let report = serde_json::json!({"out": o.out, "width": o.size.0, "height": o.size.1, "view": o.view.label(), "renderer": renderer});
let mut report = crate::picture_report(&renderer, &shown);
if let Some(r) = report.as_object_mut() {
r.insert("out".into(), o.out.clone().into());
r.insert("width".into(), o.size.0.into());
r.insert("height".into(), o.size.1.into());
r.insert("view".into(), o.view.label().into());
}
println!("{report}");
Ok(())
}
@@ -141,7 +136,13 @@ mod tests {
#[test]
fn options_are_checked() {
let o = opts(&["s.json", "--out", "a.png"]).unwrap();
assert_eq!(o, Options { script: "s.json".into(), out: "a.png".into(), view: StandardView::Iso, size: DEFAULT_SIZE });
assert_eq!(
o,
Options { script: "s.json".into(), out: "a.png".into(), view: StandardView::Iso, size: DEFAULT_SIZE, section: None, field: None }
);
let o = opts(&["s", "--out", "o", "--section", "y=2.5", "--field", "displacement"]).unwrap();
assert_eq!((o.section, o.field.as_deref()), (Some(Section { axis: 1, at: Some(2.5) }), Some("displacement")));
assert_eq!(opts(&["s", "--out", "o", "--section=Z"]).unwrap().section, Some(Section { axis: 2, at: None }));
let o = opts(&["--view=z", "s.json", "--size", "640x480", "--out=b.png"]).unwrap();
assert_eq!((o.view, o.size), (StandardView::Top, (640, 480)));
assert_eq!(opts(&["s", "--out", "o", "--view", "X"]).unwrap().view, StandardView::Right);
@@ -160,6 +161,9 @@ mod tests {
vec!["s", "--out", "o", "--size", "8192x8192"],
vec!["s", "--out", "o", "--size", "-5x10"],
vec!["s", "--out", "o", "--nope", "1"],
vec!["s", "--out", "o", "--section", "w"],
vec!["s", "--out", "o", "--section", "x=inf"],
vec!["s", "--out", "o", "--section", "x=", "--field", "f"],
] {
assert!(opts(&bad).is_err(), "{bad:?}");
}
@@ -174,19 +178,31 @@ mod tests {
(info.width, info.height, buf)
}
fn script(dir: &std::path::Path, name: &str, solve: bool) -> String {
let mut steps = fieldcraft_engine::sample::cantilever();
if solve && let Some(a) = steps.as_array_mut() {
a.push(serde_json::json!({"command": "solve.static", "params": {}}));
}
let path = dir.join(name);
std::fs::write(&path, steps.to_string()).unwrap();
path.to_string_lossy().into()
}
fn opts_for(script: String) -> Options {
Options { script, out: String::new(), view: StandardView::Iso, size: (320, 200), section: None, field: None }
}
/// The cantilever drawn headless: a PNG of the size asked for, with the model in it (pixels
/// of the hex colour) and its element edges (dark pixels). `auto` draws on the GPU when the
/// machine has one and on the CPU otherwise (a CI box without a software GPU); `cpu` always
/// on the CPU, and both pictures show the same model.
/// on the CPU, and both pictures show the same model. A section and a field change it.
#[test]
fn snapshots_the_model_and_its_mesh_headless() {
let dir = std::env::temp_dir().join(format!("fieldcraft-snapshot-{}", std::process::id()));
std::fs::create_dir_all(&dir).unwrap();
let script = dir.join("cantilever.json");
std::fs::write(&script, fieldcraft_engine::sample::cantilever().to_string()).unwrap();
let o = Options { script: script.to_string_lossy().into(), out: String::new(), view: StandardView::Iso, size: (320, 200) };
let o = opts_for(script(&dir, "cantilever.json", false));
for policy in [Policy::Auto, Policy::Cpu] {
let (png, drawn) = picture(&o, policy).unwrap();
let (png, drawn, _) = picture(&o, policy).unwrap();
let (w, h, px) = decode(&png);
assert_eq!((w, h), (320, 200), "{drawn:?}");
let hex = Palette::LIGHT.hex;
@@ -197,9 +213,18 @@ mod tests {
assert!(faces > 500, "{drawn:?}: {faces} face pixels");
assert!(edges > 100, "{drawn:?}: {edges} edge pixels");
if policy == Policy::Cpu {
assert_eq!(drawn, Drawn::Cpu { why: None });
assert_eq!(drawn, Renderer::Cpu { why: None });
}
}
// A section along the beam draws half of it.
let whole = picture(&o, Policy::Cpu).unwrap().0;
let cut = picture(&Options { section: Some(Section { axis: 0, at: None }), ..o.clone() }, Policy::Cpu).unwrap().0;
assert_ne!(whole, cut);
// A field needs a solved step; on a solved one it is the contour reported.
assert!(picture(&Options { field: Some("von_mises".into()), ..o.clone() }, Policy::Cpu).is_err());
let solved = Options { field: Some("displacement".into()), ..opts_for(script(&dir, "solved.json", true)) };
let (_, _, shown) = picture(&solved, Policy::Auto).unwrap();
assert_eq!(shown.contour.map(|c| c.0).as_deref(), Some("displacement"));
std::fs::remove_dir_all(&dir).ok();
}
}