#670: each pane of a 2- or 4-view layout chooses its own view

Problem: the extra panes of View > Switch View Layout were fixed to Top, Front and Right, and the 3D View menu only changed the main view.

Fix: every extra pane has a view selector (Active Camera, Default, Front, Left, Top, Back, Right, Bottom, Custom View 1-3). The choice is kept per comp in Views3D::panes (serde default, so older editor states load with Top/Front/Right) and set by the new command view.setPaneView {pane 0-3, view}. The Active Camera pane renders through the comp camera.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/engine/src/commands/three_d.rs

@@ -320,6 +320,21 @@ fn set_3d_view(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(switch_view(s, cid, v))
 }
 
+/// The view of one pane of the View Layout: pane 0 is the main view (the same as Switch 3D View),
+/// panes 1 to 3 are the extra views of a 2- or 4-view layout. UI state, not part of the project.
+fn set_pane_view(s: &mut Session, p: &Value) -> Result<Value> {
+    let cid = comp_id(s, p)?;
+    let v = view_p(p, "view.setPaneView")?;
+    let pane = p.get("pane").and_then(Value::as_u64).filter(|n| *n <= 3).ok_or_else(|| bad("view.setPaneView", "pane: 0 (main view) to 3"))? as usize;
+    if pane == 0 {
+        switch_view(s, cid, v);
+    } else {
+        views(s, cid).set_pane(pane - 1, v);
+    }
+    let vs = views(s, cid);
+    Ok(json!({"pane": pane, "view": v.id(), "views": [vs.current.id(), vs.pane(0).id(), vs.pane(1).id(), vs.pane(2).id()]}))
+}
+
 macro_rules! view_cmd {
     ($f:ident, $v:expr) => {
         fn $f(s: &mut Session, p: &Value) -> Result<Value> {
@@ -706,6 +721,15 @@ pub fn specs() -> Vec<CommandSpec> {
             has_comp,
             set_3d_view
         ),
+        cmd!(
+            "view.setPaneView",
+            "Set View of Pane",
+            [],
+            None,
+            "{pane: 0 (main) | 1 | 2 | 3, view: activeCamera|default|front|left|top|back|right|bottom|custom1|custom2|custom3, comp?}",
+            has_comp,
+            set_pane_view
+        ),
         cmd!("view.3d.activeCamera", "Active Camera", ["View", "Switch 3D View"], Some("F12"), "{comp?}", has_comp, view_active),
         cmd!("view.3d.default", "Default", ["View", "Switch 3D View"], None, "{comp?}", has_comp, view_default),
         cmd!("view.3d.front", "Front", ["View", "Switch 3D View"], Some("F10"), "{comp?}", has_comp, view_front),

crates/engine/src/tests_3d.rs

@@ -243,3 +243,25 @@ fn demo_has_3d_showcase() {
     let lit = img.data.iter().filter(|p| p[3] > 0.99 && p[0] + p[1] + p[2] > 0.3).count();
     assert!(lit > 2_000, "{lit}");
 }
+
+/// #670: the views of the panes of a multi-view layout are chosen per pane, kept per comp, and
+/// editor states saved before panes existed load with the default Top / Front / Right.
+#[test]
+fn layout_panes_choose_their_view() {
+    use effectcraft_render::three_d::{View3D, Views3D};
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "C", "width": 640, "height": 360, "duration": 2})).unwrap();
+    let cid = s.active_comp_id().unwrap();
+    assert_eq!(s.state.views3d.get(&cid).cloned().unwrap_or_default().pane(0), View3D::Top);
+    let r = s.execute("view.setPaneView", json!({"pane": 2, "view": "bottom"})).unwrap();
+    assert_eq!(r["views"], json!(["activeCamera", "top", "bottom", "right"]));
+    assert_eq!(s.state.views3d[&cid].current, View3D::ActiveCamera, "the main view is untouched");
+    s.execute("view.setPaneView", json!({"pane": 0, "view": "custom1"})).unwrap();
+    assert_eq!(s.state.views3d[&cid].current, View3D::Custom1);
+    assert!(s.execute("view.setPaneView", json!({"pane": 4, "view": "top"})).is_err());
+    assert!(s.execute("view.setPaneView", json!({"pane": 1, "view": "nope"})).is_err());
+    let back: crate::EditorState = serde_json::from_value(serde_json::to_value(&s.state).unwrap()).unwrap();
+    assert_eq!(back.views3d[&cid].pane(1), View3D::Bottom);
+    let old: Views3D = serde_json::from_value(json!({"current": "Front"})).unwrap();
+    assert_eq!((old.current, old.pane(0), old.pane(1), old.pane(2)), (View3D::Front, View3D::Top, View3D::Front, View3D::Right));
+}