refactor: build sorted camera render requests

engine/src/Rendering/SceneRenderer.cpp

@@ -1,6 +1,8 @@
 #include "Rendering/SceneRenderer.h"
 
 #include "Components/CameraComponent.h"
+#include "Components/GameObject.h"
+#include "Scene/Scene.h"
 
 #include <algorithm>
 
@@ -17,6 +19,13 @@ bool CompareCameraRenderRequest(const CameraRenderRequest& lhs, const CameraRend
     return lhs.camera < rhs.camera;
 }
 
+bool IsUsableCamera(const Components::CameraComponent* camera) {
+    return camera != nullptr &&
+           camera->IsEnabled() &&
+           camera->GetGameObject() != nullptr &&
+           camera->GetGameObject()->IsActiveInHierarchy();
+}
+
 } // namespace
 
 SceneRenderer::SceneRenderer() = default;
@@ -44,19 +53,45 @@ std::vector<CameraRenderRequest> SceneRenderer::BuildRenderRequests(
     const RenderSurface& surface) const {
     std::vector<CameraRenderRequest> requests;
 
-    Components::CameraComponent* camera = m_sceneExtractor.SelectCamera(scene, overrideCamera);
-    if (camera == nullptr) {
-        return requests;
+    std::vector<Components::CameraComponent*> cameras;
+    if (IsUsableCamera(overrideCamera)) {
+        cameras.push_back(overrideCamera);
+    } else {
+        cameras = scene.FindObjectsOfType<Components::CameraComponent>();
+        cameras.erase(
+            std::remove_if(
+                cameras.begin(),
+                cameras.end(),
+                [](const Components::CameraComponent* camera) {
+                    return !IsUsableCamera(camera);
+                }),
+            cameras.end());
+    }
+
+    std::stable_sort(
+        cameras.begin(),
+        cameras.end(),
+        [](const Components::CameraComponent* lhs, const Components::CameraComponent* rhs) {
+            if (lhs->GetDepth() != rhs->GetDepth()) {
+                return lhs->GetDepth() < rhs->GetDepth();
+            }
+
+            return lhs < rhs;
+        });
+
+    for (size_t cameraIndex = 0; cameraIndex < cameras.size(); ++cameraIndex) {
+        Components::CameraComponent* camera = cameras[cameraIndex];
+
+        CameraRenderRequest request;
+        request.scene = &scene;
+        request.camera = camera;
+        request.context = context;
+        request.surface = surface;
+        request.cameraDepth = camera->GetDepth();
+        request.clearFlags = cameraIndex == 0 ? RenderClearFlags::All : RenderClearFlags::Depth;
+        requests.push_back(request);
     }
 
-    CameraRenderRequest request;
-    request.scene = &scene;
-    request.camera = camera;
-    request.context = context;
-    request.surface = surface;
-    request.cameraDepth = camera->GetDepth();
-    request.clearFlags = RenderClearFlags::All;
-    requests.push_back(request);
     return requests;
 }