mcp, cli, ui: camera target, fit and fov in screenshots, snapshot --camera and ui.camera; screenshot section (#467)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/ui-egui/src/control.rs

@@ -327,11 +327,8 @@ pub fn handle(app: &mut ModelApp, ctx: &egui::Context, req: &ControlRequest) ->
             }
             ok(json!(app.cam))
         }
-        "ui.camera" => match fieldcraft_engine::view::orientation(p) {
-            Ok(o) => {
-                app.cam.orient(&o);
-                ok(json!(app.cam))
-            }
+        "ui.camera" => match fieldcraft_engine::view::camera(p).map_err(|e| e.to_string()).and_then(|a| app.aim_camera(&a)) {
+            Ok(()) => ok(json!(app.cam)),
             Err(e) => err(e),
         },
         "ui.start" => {
@@ -748,6 +745,13 @@ mod tests {
         }
         assert_eq!(app.cam.distance, 250.0);
         assert_eq!(call(&mut app, "ui.camera", json!({"yaw": -1e12, "pitch": 1e300, "distance": 1e300}))["ok"], true);
+        // Aimed at a point it looks at it; at the model's centre of mass, framed (#467).
+        let r = call(&mut app, "ui.camera", json!({"yaw": 30, "pitch": 20, "target": [1, 2, 3], "distance": 40}));
+        assert_eq!((app.cam.target, app.cam.distance), (fieldcraft_render::Vec3::new(1.0, 2.0, 3.0), 40.0), "{r}");
+        let r = call(&mut app, "ui.camera", json!({"yaw": 30, "pitch": 20, "target": {"center_of": "mass"}, "fit": true}));
+        assert_eq!(r["ok"], true, "{r}");
+        assert!(app.cam.target.dist(fieldcraft_render::Vec3::new(1.0, 2.0, 3.0)) > 1.0 && app.cam.distance < 1e8, "{r}");
+        assert_eq!(call(&mut app, "ui.camera", json!({"yaw": 0, "pitch": 0, "target": {"bodies": ["Nope"]}}))["ok"], false);
         assert!(app.cam.is_valid() && app.cam.pitch < std::f64::consts::FRAC_PI_2);
         assert_eq!(call(&mut app, "ui.inspect", json!({}))["result"]["model"]["elements"], 64 + 162);
         assert_eq!(call(&mut app, "ui.screenshot", json!({})), json!({"screenshot": true}));

crates/ui-egui/src/lib.rs

@@ -1894,6 +1894,16 @@ impl ModelApp {
         self.fit_view();
     }
 
+    /// Aim the camera as `aim` says ([`fieldcraft_engine::view::camera`], the control channel's
+    /// `ui.camera`): turned, and with a target moved to look at it from the view's free part, as
+    /// a standard view moves it. A framing still waiting is dropped.
+    pub fn aim_camera(&mut self, aim: &fieldcraft_engine::view::Aim) -> Result<(), String> {
+        let (aspect, _) = self.free_part();
+        self.cam = fieldcraft_engine::view::aim(&self.session, aim, self.cam, aspect).map_err(|e| e.to_string())?;
+        self.reframe = None;
+        Ok(())
+    }
+
     /// Do the framing asked for ([`framing::Reframe`]) once there is something to frame; the
     /// viewport calls it when it knows its size and its overlays, before drawing.
     pub(crate) fn apply_reframe(&mut self) {