XCEngine/editor/app/Services/Engine/EngineSceneViewportBridge.cpp

#include "Engine/EngineSceneViewportBridge.h"

#include <XCEngine/Components/CameraComponent.h>
#include <XCEngine/Components/GameObject.h>
#include <XCEngine/Components/TransformComponent.h>
#include <XCEngine/Rendering/Execution/SceneRenderer.h>
#include <XCEngine/Rendering/Picking/RenderObjectIdRegistry.h>
#include <XCEngine/Scene/Scene.h>
#include <XCEngine/Scene/SceneManager.h>

#include <algorithm>
#include <cmath>
#include <vector>

namespace XCEngine::UI::Editor::App {

namespace {

using ::XCEngine::Components::GameObject;
using ::XCEngine::Components::Scene;
using ::XCEngine::Components::SceneManager;
using ::XCEngine::Components::TransformComponent;
using ::XCEngine::Math::Quaternion;
using ::XCEngine::Math::Vector3;
using ::XCEngine::Rendering::RenderObjectId;
using ::XCEngine::Rendering::RenderObjectIdRegistry;

Scene* ResolvePrimaryScene(SceneManager& sceneManager) {
    if (Scene* activeScene = sceneManager.GetActiveScene();
        activeScene != nullptr) {
        return activeScene;
    }

    const std::vector<Scene*> scenes = sceneManager.GetAllScenes();
    if (!scenes.empty() && scenes.front() != nullptr) {
        sceneManager.SetActiveScene(scenes.front());
        return scenes.front();
    }

    return nullptr;
}

} // namespace

EngineSceneViewportBridge::~EngineSceneViewportBridge() = default;

void EngineSceneViewportBridge::Shutdown() {
    m_sceneViewportCamera = nullptr;
    m_sceneViewportCameraObject.reset();
}

SceneViewportFramePlanBuildStatus EngineSceneViewportBridge::BuildFramePlan(
    const SceneViewportRenderRequest& request,
    const ::XCEngine::Rendering::RenderContext& renderContext,
    const ::XCEngine::Rendering::RenderSurface& surface,
    ::XCEngine::Rendering::CameraFramePlan& outFramePlan) {
    outFramePlan = {};
    if (!request.IsValid()) {
        return SceneViewportFramePlanBuildStatus::InvalidRequest;
    }

    Scene* scene = ResolvePrimaryScene(SceneManager::Get());
    if (scene == nullptr) {
        return SceneViewportFramePlanBuildStatus::NoActiveScene;
    }

    if (!EnsureSceneViewportCamera()) {
        return SceneViewportFramePlanBuildStatus::Failed;
    }

    ConfigureSceneViewportCamera(request.camera);
    const std::vector<::XCEngine::Rendering::CameraFramePlan> framePlans =
        m_sceneViewportRenderer.BuildFramePlans(
            *scene,
            m_sceneViewportCamera,
            renderContext,
            surface);
    if (framePlans.empty() || !framePlans.front().IsValid()) {
        return SceneViewportFramePlanBuildStatus::Failed;
    }

    outFramePlan = framePlans.front();
    return SceneViewportFramePlanBuildStatus::Success;
}

bool EngineSceneViewportBridge::RenderFramePlan(
    const ::XCEngine::Rendering::CameraFramePlan& framePlan) {
    return framePlan.IsValid() &&
        m_sceneViewportRenderer.Render(framePlan);
}

bool EngineSceneViewportBridge::TryResolveActiveSceneRenderObjectId(
    RenderObjectId renderObjectId,
    EditorSceneObjectId& outRuntimeObjectId) const {
    outRuntimeObjectId = kInvalidEditorSceneObjectId;

    std::uint64_t runtimeObjectId = kInvalidEditorSceneObjectId;
    if (!RenderObjectIdRegistry::Get().TryResolveRuntimeObjectId(
            renderObjectId,
            runtimeObjectId)) {
        return false;
    }

    Scene* scene = ResolvePrimaryScene(SceneManager::Get());
    GameObject* gameObject =
        scene != nullptr
            ? scene->FindByID(static_cast<EditorSceneObjectId>(runtimeObjectId))
            : nullptr;
    if (gameObject == nullptr) {
        return false;
    }

    outRuntimeObjectId = gameObject->GetID();
    return true;
}

bool EngineSceneViewportBridge::EnsureSceneViewportCamera() {
    if (m_sceneViewportCameraObject != nullptr &&
        m_sceneViewportCamera != nullptr) {
        return true;
    }

    m_sceneViewportCamera = nullptr;
    m_sceneViewportCameraObject =
        std::make_unique<GameObject>("EditorSceneViewportCamera");
    m_sceneViewportCamera =
        m_sceneViewportCameraObject->AddComponent<
            ::XCEngine::Components::CameraComponent>();
    if (m_sceneViewportCamera == nullptr) {
        m_sceneViewportCameraObject.reset();
        return false;
    }

    m_sceneViewportCamera->SetPrimary(false);
    m_sceneViewportCamera->SetProjectionType(
        ::XCEngine::Components::CameraProjectionType::Perspective);
    m_sceneViewportCamera->SetFieldOfView(60.0f);
    m_sceneViewportCamera->SetNearClipPlane(0.03f);
    m_sceneViewportCamera->SetFarClipPlane(2000.0f);
    return true;
}

void EngineSceneViewportBridge::ConfigureSceneViewportCamera(
    const EditorSceneCameraSnapshot& snapshot) {
    if (!EnsureSceneViewportCamera() ||
        m_sceneViewportCameraObject == nullptr ||
        m_sceneViewportCamera == nullptr) {
        return;
    }

    TransformComponent* transform =
        m_sceneViewportCameraObject->GetTransform();
    if (transform == nullptr) {
        return;
    }

    Vector3 forward = snapshot.forward.SqrMagnitude() >
            ::XCEngine::Math::EPSILON
        ? snapshot.forward.Normalized()
        : Vector3::Forward();
    Vector3 up = snapshot.up.SqrMagnitude() >
            ::XCEngine::Math::EPSILON
        ? snapshot.up.Normalized()
        : Vector3::Up();
    if (Vector3::Cross(forward, up).SqrMagnitude() <=
        ::XCEngine::Math::EPSILON) {
        up = std::abs(Vector3::Dot(forward, Vector3::Up())) < 0.999f
            ? Vector3::Up()
            : Vector3::Right();
    }

    transform->SetPosition(snapshot.position);
    transform->SetRotation(Quaternion::LookRotation(forward, up));

    const float nearClipPlane = (std::max)(snapshot.nearClipPlane, 0.001f);
    const float farClipPlane =
        (std::max)(snapshot.farClipPlane, nearClipPlane + 0.001f);
    m_sceneViewportCamera->SetPrimary(false);
    m_sceneViewportCamera->SetProjectionType(
        ::XCEngine::Components::CameraProjectionType::Perspective);
    m_sceneViewportCamera->SetFieldOfView(
        std::clamp(snapshot.verticalFovDegrees, 1.0f, 179.0f));
    m_sceneViewportCamera->SetNearClipPlane(nearClipPlane);
    m_sceneViewportCamera->SetFarClipPlane(farClipPlane);
}

} // namespace XCEngine::UI::Editor::App