Test that an Environment light visibly lights the scene (#2436)

End-to-end regression tests for the issue's report, through the real command
path (what the Light Settings dialog runs) and the real viewer: adding an
Environment light to a Classic 3D comp switches it to Advanced 3D and changes
the viewer's pixels — a red light at full intensity, the default white light,
and the same on the GPU compositor (skips without an adapter, like ui_gpu).

crates/ui-egui/tests/it/main.rs

@@ -20,6 +20,8 @@ mod ui_drag_drop;
 mod ui_effect_controls;
 mod ui_effect_drop_highlight;
 mod ui_effect_names;
+mod ui_env_light_gpu;
+mod ui_env_light_repro;
 mod ui_font_search;
 mod ui_form_fit;
 mod ui_frame_step;

crates/ui-egui/tests/it/ui_env_light_gpu.rs

@@ -0,0 +1,79 @@
+//! The Environment light through the app's GPU compositor (egui_kittest with wgpu): adding one
+//! visibly changes the viewer's GPU frames (#2436). Skips without a GPU adapter (CI).
+
+use effectcraft_engine::Session;
+use effectcraft_engine::project::Renderer;
+use effectcraft_ui_egui::EffectcraftApp;
+use egui_kittest::Harness;
+use serde_json::json;
+
+fn settle(h: &mut Harness<'_, EffectcraftApp>) {
+    for _ in 0..600 {
+        h.step();
+        if h.state().frames.inflight() == 0 && h.state().frames.last_ms.lock().map(|v| *v > 0.0).unwrap_or(false) {
+            break;
+        }
+        std::thread::sleep(std::time::Duration::from_millis(20));
+    }
+    for _ in 0..4 {
+        h.step();
+    }
+}
+
+/// egui_kittest's wgpu setup on the adapter the headless compositor picked, so the viewer's GPU
+/// compositor attaches (see ui_gpu.rs).
+fn same_adapter(name: String) -> eframe::egui_wgpu::WgpuSetup {
+    let mut setup = egui_kittest::wgpu::default_wgpu_setup();
+    if let eframe::egui_wgpu::WgpuSetup::CreateNew(c) = &mut setup {
+        let fallback = c.native_adapter_selector.take();
+        c.native_adapter_selector = Some(std::sync::Arc::new(move |adapters, surface| {
+            let named = |a: &&eframe::wgpu::Adapter| format!("{} ({:?})", a.get_info().name, a.get_info().backend) == name;
+            match (adapters.iter().find(named), &fallback) {
+                (Some(a), _) => Ok(a.clone()),
+                (None, Some(f)) => f(adapters, surface),
+                (None, None) => adapters.first().cloned().ok_or_else(|| "No adapter found".to_owned()),
+            }
+        }));
+    }
+    setup
+}
+
+/// A red Environment light at full intensity lights the scene on the GPU compositor too: the
+/// viewer's GPU frames change when the light is added.
+#[test]
+fn environment_light_lights_the_scene_on_the_gpu() {
+    let Some(probe) = effectcraft_gpu::Gpu::headless() else {
+        eprintln!("no GPU adapter: skipping");
+        return;
+    };
+    let adapter = effectcraft_engine::render::Accelerator::name(&probe);
+    eprintln!("headless compositor adapter: {adapter}");
+    let gl = adapter.ends_with("(Gl)");
+    drop(probe);
+    let mut s = Session::default();
+    s.execute("file.openDemoProject", json!({})).unwrap();
+    s.execute("comp.open", json!({"comp": "3D Showcase"})).unwrap();
+    s.execute("time.set", json!({"time": 5.0})).unwrap();
+    s.execute("comp.settings", json!({"renderer": "classic3D"})).unwrap();
+    let mut h = Harness::builder()
+        .with_size(egui::vec2(1400.0, 900.0))
+        .with_pixels_per_point(1.0)
+        .wgpu_setup(same_adapter(adapter))
+        .build_eframe(|_| EffectcraftApp::new(s));
+    settle(&mut h);
+    if gl && h.state().gpu_adapter().is_none() {
+        eprintln!("egui-wgpu's GL device has WebGL2 limits: the viewer stays on the CPU, skipping");
+        return;
+    }
+    assert!(h.state().gpu_adapter().is_some(), "GPU compositor on egui-wgpu's device");
+    let before = h.state_mut().viewer_pixels().expect("GPU frame before adding the light").pixels.clone();
+
+    h.state_mut().session.execute("layer.newLight", json!({"kind": "Environment", "color": [1.0, 0.0, 0.0], "intensity": 100.0})).unwrap();
+    assert_eq!(h.state().session.active_comp().unwrap().renderer, Renderer::Advanced3D);
+    settle(&mut h);
+    let after = h.state_mut().viewer_pixels().expect("GPU frame after adding the light").pixels.clone();
+
+    assert_eq!(before.len(), after.len());
+    let diff = before.iter().zip(&after).filter(|(a, b)| a != b).count();
+    assert!(diff > 500, "a red Environment light at 100 % changed only {diff} GPU pixels");
+}

crates/ui-egui/tests/it/ui_env_light_repro.rs

@@ -0,0 +1,75 @@
+//! Reproduction of issue #2436's report: an Environment light added through the real command
+//! path (what the Light Settings dialog runs) must visibly light the scene in the viewer.
+
+use effectcraft_engine::Session;
+use effectcraft_engine::project::Renderer;
+use effectcraft_ui_egui::EffectcraftApp;
+use egui_kittest::Harness;
+use serde_json::json;
+
+fn app() -> EffectcraftApp {
+    let mut s = Session::default();
+    s.execute("file.openDemoProject", json!({})).unwrap();
+    s.execute("comp.open", json!({"comp": "3D Showcase"})).unwrap();
+    s.execute("time.set", json!({"time": 5.0})).unwrap();
+    EffectcraftApp::new(s)
+}
+
+/// Step the UI until background frame renders have landed.
+fn settle(h: &mut Harness<'_, EffectcraftApp>) {
+    for _ in 0..600 {
+        h.step();
+        if h.state().frames.inflight() == 0 && h.state().frames.last_ms.lock().map(|v| *v > 0.0).unwrap_or(false) {
+            break;
+        }
+        std::thread::sleep(std::time::Duration::from_millis(20));
+    }
+    for _ in 0..4 {
+        h.step();
+    }
+}
+
+fn changed_pixels(before: &[egui::Color32], after: &[egui::Color32]) -> usize {
+    before.iter().zip(after).filter(|(a, b)| a != b).count()
+}
+
+/// An Environment light (red, full intensity, no source: the flat default environment) added to
+/// a Classic 3D comp switches it to Advanced 3D and visibly changes the viewer's pixels.
+#[test]
+fn environment_light_lights_the_scene() {
+    let mut h = Harness::builder().with_size(egui::vec2(1600.0, 1000.0)).build_eframe(|_| app());
+    h.state_mut().session.execute("comp.settings", json!({"renderer": "classic3D"})).unwrap();
+    h.run_steps(3);
+    settle(&mut h);
+    let before = h.state_mut().viewer_pixels().expect("frame before adding the light").pixels.clone();
+
+    h.state_mut().session.execute("layer.newLight", json!({"kind": "Environment", "color": [1.0, 0.0, 0.0], "intensity": 100.0})).unwrap();
+
+    assert_eq!(h.state().session.active_comp().unwrap().renderer, Renderer::Advanced3D, "the comp switched to Advanced 3D");
+    settle(&mut h);
+    let after = h.state_mut().viewer_pixels().expect("frame after adding the light").pixels.clone();
+    assert_eq!(before.len(), after.len());
+    let diff = changed_pixels(&before, &after);
+    assert!(diff > 500, "a red Environment light at 100 % changed only {diff} pixels");
+}
+
+/// The literal action from the issue: default white Environment light, defaults everywhere —
+/// even then the lighting model changes (Advanced 3D IBL instead of unlit/Classic), so pixels
+/// must change somewhere in the comp frame.
+#[test]
+fn default_environment_light_changes_the_scene() {
+    let mut h = Harness::builder().with_size(egui::vec2(1600.0, 1000.0)).build_eframe(|_| app());
+    h.state_mut().session.execute("comp.settings", json!({"renderer": "classic3D"})).unwrap();
+    h.run_steps(3);
+    settle(&mut h);
+    let before = h.state_mut().viewer_pixels().expect("frame before adding the light").pixels.clone();
+
+    h.state_mut().session.execute("layer.newLight", json!({"kind": "Environment"})).unwrap();
+
+    assert_eq!(h.state().session.active_comp().unwrap().renderer, Renderer::Advanced3D);
+    settle(&mut h);
+    let after = h.state_mut().viewer_pixels().expect("frame after adding the light").pixels.clone();
+    assert_eq!(before.len(), after.len());
+    let diff = changed_pixels(&before, &after);
+    assert!(diff > 500, "a default white Environment light changed only {diff} pixels");
+}