XCEngine/editor/src/panels/SceneViewPanel.cpp

#include "Actions/ActionRouting.h"
#include "Core/IEditorContext.h"
#include "Core/ISceneManager.h"
#include "Core/ISelectionManager.h"
#include "SceneViewPanel.h"
#include "Viewport/SceneViewportOrientationGizmo.h"
#include "Viewport/SceneViewportOverlayRenderer.h"
#include "ViewportPanelContent.h"
#include "UI/UI.h"

#include <imgui.h>

namespace XCEngine {
namespace Editor {

namespace {

SceneViewportMoveGizmoContext BuildMoveGizmoContext(
    IEditorContext& context,
    const SceneViewportOverlayData& overlay,
    const ViewportPanelContentResult& content,
    const ImVec2& mousePosition) {
    SceneViewportMoveGizmoContext gizmoContext = {};
    gizmoContext.overlay = overlay;
    gizmoContext.viewportSize = Math::Vector2(content.availableSize.x, content.availableSize.y);
    gizmoContext.mousePosition = Math::Vector2(
        mousePosition.x - content.itemMin.x,
        mousePosition.y - content.itemMin.y);

    if (context.GetSelectionManager().GetSelectionCount() == 1) {
        const uint64_t selectedEntity = context.GetSelectionManager().GetSelectedEntity();
        if (selectedEntity != 0) {
            gizmoContext.selectedObject = context.GetSceneManager().GetEntity(selectedEntity);
        }
    }

    return gizmoContext;
}

SceneViewportRotateGizmoContext BuildRotateGizmoContext(
    IEditorContext& context,
    const SceneViewportOverlayData& overlay,
    const ViewportPanelContentResult& content,
    const ImVec2& mousePosition) {
    SceneViewportRotateGizmoContext gizmoContext = {};
    gizmoContext.overlay = overlay;
    gizmoContext.viewportSize = Math::Vector2(content.availableSize.x, content.availableSize.y);
    gizmoContext.mousePosition = Math::Vector2(
        mousePosition.x - content.itemMin.x,
        mousePosition.y - content.itemMin.y);

    if (context.GetSelectionManager().GetSelectionCount() == 1) {
        const uint64_t selectedEntity = context.GetSelectionManager().GetSelectedEntity();
        if (selectedEntity != 0) {
            gizmoContext.selectedObject = context.GetSceneManager().GetEntity(selectedEntity);
        }
    }

    return gizmoContext;
}

} // namespace

SceneViewPanel::SceneViewPanel() : Panel("Scene") {}

void SceneViewPanel::Render() {
    ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
    UI::PanelWindowScope panel(m_name.c_str());
    ImGui::PopStyleVar();
    if (!panel.IsOpen()) {
        return;
    }

    const ViewportPanelContentResult content = RenderViewportPanelContent(*m_context, EditorViewportKind::Scene);
    if (IViewportHostService* viewportHostService = m_context->GetViewportHostService()) {
        const ImGuiIO& io = ImGui::GetIO();
        const bool hasInteractiveViewport = content.hasViewportArea && content.frame.hasTexture;

        if (content.focused && !io.WantTextInput && !m_lookDragging && !m_panDragging) {
            if (ImGui::IsKeyPressed(ImGuiKey_W, false)) {
                if (m_rotateGizmo.IsActive()) {
                    m_rotateGizmo.CancelDrag(&m_context->GetUndoManager());
                }
                m_transformTool = SceneViewportTransformTool::Move;
            } else if (ImGui::IsKeyPressed(ImGuiKey_E, false)) {
                if (m_moveGizmo.IsActive()) {
                    m_moveGizmo.CancelDrag(&m_context->GetUndoManager());
                }
                m_transformTool = SceneViewportTransformTool::Rotate;
            }
        }

        const bool usingMoveGizmo = m_transformTool == SceneViewportTransformTool::Move;
        SceneViewportOverlayData overlay = {};
        SceneViewportMoveGizmoContext moveGizmoContext = {};
        SceneViewportRotateGizmoContext rotateGizmoContext = {};

        if (hasInteractiveViewport) {
            overlay = viewportHostService->GetSceneViewOverlayData();
            if (usingMoveGizmo) {
                if (m_rotateGizmo.IsActive()) {
                    m_rotateGizmo.CancelDrag(&m_context->GetUndoManager());
                }

                moveGizmoContext = BuildMoveGizmoContext(*m_context, overlay, content, io.MousePos);
                if (m_moveGizmo.IsActive() &&
                    (moveGizmoContext.selectedObject == nullptr ||
                     m_context->GetSelectionManager().GetSelectedEntity() != m_moveGizmo.GetActiveEntityId())) {
                    m_moveGizmo.CancelDrag(&m_context->GetUndoManager());
                }
                m_moveGizmo.Update(moveGizmoContext);
            } else {
                if (m_moveGizmo.IsActive()) {
                    m_moveGizmo.CancelDrag(&m_context->GetUndoManager());
                }

                rotateGizmoContext = BuildRotateGizmoContext(*m_context, overlay, content, io.MousePos);
                if (m_rotateGizmo.IsActive() &&
                    (rotateGizmoContext.selectedObject == nullptr ||
                     m_context->GetSelectionManager().GetSelectedEntity() != m_rotateGizmo.GetActiveEntityId())) {
                    m_rotateGizmo.CancelDrag(&m_context->GetUndoManager());
                }
                m_rotateGizmo.Update(rotateGizmoContext);
            }
        } else {
            if (m_moveGizmo.IsActive()) {
                m_moveGizmo.CancelDrag(&m_context->GetUndoManager());
            }
            if (m_rotateGizmo.IsActive()) {
                m_rotateGizmo.CancelDrag(&m_context->GetUndoManager());
            }
        }

        const bool gizmoHovering = usingMoveGizmo ? m_moveGizmo.IsHoveringHandle() : m_rotateGizmo.IsHoveringHandle();
        const bool gizmoActive = usingMoveGizmo ? m_moveGizmo.IsActive() : m_rotateGizmo.IsActive();

        const bool beginTransformGizmo =
            hasInteractiveViewport &&
            content.clickedLeft &&
            !m_lookDragging &&
            !m_panDragging &&
            gizmoHovering;
        const SceneViewportOrientationAxis orientationAxisHit =
            hasInteractiveViewport &&
            content.hovered &&
            !m_lookDragging &&
            !m_panDragging &&
            !gizmoHovering &&
            !gizmoActive
                ? HitTestSceneViewportOrientationGizmo(
                    overlay,
                    content.itemMin,
                    content.itemMax,
                    io.MousePos)
                : SceneViewportOrientationAxis::None;
        const bool orientationGizmoClick =
            hasInteractiveViewport &&
            content.clickedLeft &&
            orientationAxisHit != SceneViewportOrientationAxis::None;
        const bool selectClick =
            hasInteractiveViewport &&
            content.clickedLeft &&
            !m_lookDragging &&
            !m_panDragging &&
            !orientationGizmoClick &&
            !gizmoHovering &&
            !gizmoActive;
        const bool beginLookDrag =
            hasInteractiveViewport &&
            content.hovered &&
            !m_lookDragging &&
            !gizmoActive &&
            ImGui::IsMouseClicked(ImGuiMouseButton_Right);
        const bool beginPanDrag =
            hasInteractiveViewport &&
            content.hovered &&
            !m_panDragging &&
            !gizmoActive &&
            !m_lookDragging &&
            ImGui::IsMouseClicked(ImGuiMouseButton_Middle);

        if (beginTransformGizmo || orientationGizmoClick || selectClick || beginLookDrag || beginPanDrag) {
            ImGui::SetWindowFocus();
        }

        if (beginTransformGizmo) {
            if (usingMoveGizmo) {
                m_moveGizmo.TryBeginDrag(moveGizmoContext, m_context->GetUndoManager());
            } else {
                m_rotateGizmo.TryBeginDrag(rotateGizmoContext, m_context->GetUndoManager());
            }
        }

        if (orientationGizmoClick) {
            viewportHostService->AlignSceneViewToOrientationAxis(orientationAxisHit);
            overlay = viewportHostService->GetSceneViewOverlayData();
            if (usingMoveGizmo) {
                moveGizmoContext = BuildMoveGizmoContext(*m_context, overlay, content, io.MousePos);
                m_moveGizmo.Update(moveGizmoContext);
            } else {
                rotateGizmoContext = BuildRotateGizmoContext(*m_context, overlay, content, io.MousePos);
                m_rotateGizmo.Update(rotateGizmoContext);
            }
        }

        if (selectClick) {
            const ImVec2 localMousePosition(
                io.MousePos.x - content.itemMin.x,
                io.MousePos.y - content.itemMin.y);
            const uint64_t selectedEntity = viewportHostService->PickSceneViewEntity(
                *m_context,
                content.availableSize,
                localMousePosition);
            if (selectedEntity != 0) {
                m_context->GetSelectionManager().SetSelectedEntity(selectedEntity);
            } else {
                m_context->GetSelectionManager().ClearSelection();
            }
        }

        if (gizmoActive) {
            if (ImGui::IsMouseDown(ImGuiMouseButton_Left)) {
                if (usingMoveGizmo) {
                    m_moveGizmo.UpdateDrag(moveGizmoContext);
                } else {
                    m_rotateGizmo.UpdateDrag(rotateGizmoContext);
                }
            } else {
                if (usingMoveGizmo) {
                    m_moveGizmo.EndDrag(m_context->GetUndoManager());
                } else {
                    m_rotateGizmo.EndDrag(m_context->GetUndoManager());
                }
            }
        }

        if (beginLookDrag) {
            m_lookDragging = true;
            m_panDragging = false;
            m_lastLookDragDelta = ImVec2(0.0f, 0.0f);
            m_lastPanDragDelta = ImVec2(0.0f, 0.0f);
        }
        if (beginPanDrag) {
            m_panDragging = true;
            m_lookDragging = false;
            m_lastPanDragDelta = ImVec2(0.0f, 0.0f);
            m_lastLookDragDelta = ImVec2(0.0f, 0.0f);
        }

        if (m_lookDragging && !ImGui::IsMouseDown(ImGuiMouseButton_Right)) {
            m_lookDragging = false;
            m_lastLookDragDelta = ImVec2(0.0f, 0.0f);
        }
        if (m_panDragging && !ImGui::IsMouseDown(ImGuiMouseButton_Middle)) {
            m_panDragging = false;
            m_lastPanDragDelta = ImVec2(0.0f, 0.0f);
        }

        if (m_lookDragging || m_panDragging || m_moveGizmo.IsActive() || m_rotateGizmo.IsActive()) {
            ImGui::SetNextFrameWantCaptureMouse(true);
        }
        if (m_lookDragging) {
            ImGui::SetNextFrameWantCaptureKeyboard(true);
        }

        SceneViewportInput input = {};
        input.viewportSize = content.availableSize;
        input.deltaTime = io.DeltaTime;
        input.hovered = content.hovered;
        input.focused = content.focused || m_lookDragging || m_panDragging;
        input.mouseWheel = (content.hovered && !m_lookDragging) ? io.MouseWheel : 0.0f;
        input.flySpeedDelta = (content.hovered && m_lookDragging) ? io.MouseWheel : 0.0f;
        input.looking = m_lookDragging;
        input.orbiting = false;
        input.panning = m_panDragging;
        input.fastMove = io.KeyShift;
        input.focusSelectionRequested =
            input.focused && !io.WantTextInput && ImGui::IsKeyPressed(ImGuiKey_F, false);

        if (m_lookDragging && !io.WantTextInput) {
            input.moveForward =
                (ImGui::IsKeyDown(ImGuiKey_W) ? 1.0f : 0.0f) -
                (ImGui::IsKeyDown(ImGuiKey_S) ? 1.0f : 0.0f);
            input.moveRight =
                (ImGui::IsKeyDown(ImGuiKey_D) ? 1.0f : 0.0f) -
                (ImGui::IsKeyDown(ImGuiKey_A) ? 1.0f : 0.0f);
            input.moveUp =
                (ImGui::IsKeyDown(ImGuiKey_E) ? 1.0f : 0.0f) -
                (ImGui::IsKeyDown(ImGuiKey_Q) ? 1.0f : 0.0f);
        }

        if (m_lookDragging || m_panDragging) {
            if (m_lookDragging) {
                const ImVec2 lookDragDelta = ImGui::GetMouseDragDelta(ImGuiMouseButton_Right, 0.0f);
                input.mouseDelta.x += lookDragDelta.x - m_lastLookDragDelta.x;
                input.mouseDelta.y += lookDragDelta.y - m_lastLookDragDelta.y;
                m_lastLookDragDelta = lookDragDelta;
            } else {
                m_lastLookDragDelta = ImVec2(0.0f, 0.0f);
            }

            if (m_panDragging) {
                const ImVec2 panDragDelta = ImGui::GetMouseDragDelta(ImGuiMouseButton_Middle, 0.0f);
                ImVec2 framePanDelta(
                    panDragDelta.x - m_lastPanDragDelta.x,
                    panDragDelta.y - m_lastPanDragDelta.y);
                // Some middle-button drags report a zero drag delta on the interaction surface.
                if ((framePanDelta.x == 0.0f && framePanDelta.y == 0.0f) &&
                    (io.MouseDelta.x != 0.0f || io.MouseDelta.y != 0.0f)) {
                    framePanDelta = io.MouseDelta;
                }
                input.mouseDelta.x += framePanDelta.x;
                input.mouseDelta.y += framePanDelta.y;
                m_lastPanDragDelta = panDragDelta;
            } else {
                m_lastPanDragDelta = ImVec2(0.0f, 0.0f);
            }
        }

        viewportHostService->UpdateSceneViewInput(*m_context, input);

        if (content.hasViewportArea && content.frame.hasTexture) {
            overlay = viewportHostService->GetSceneViewOverlayData();
            if (usingMoveGizmo) {
                moveGizmoContext = BuildMoveGizmoContext(*m_context, overlay, content, io.MousePos);
                m_moveGizmo.Update(moveGizmoContext);
            } else {
                rotateGizmoContext = BuildRotateGizmoContext(*m_context, overlay, content, io.MousePos);
                m_rotateGizmo.Update(rotateGizmoContext);
            }

            DrawSceneViewportOverlay(
                ImGui::GetWindowDrawList(),
                overlay,
                content.itemMin,
                content.itemMax,
                content.availableSize,
                usingMoveGizmo ? &m_moveGizmo.GetDrawData() : nullptr,
                usingMoveGizmo ? nullptr : &m_rotateGizmo.GetDrawData());
        }
    }

    Actions::ObserveInactiveActionRoute(*m_context);
}

}
}