Formalize scene viewport HUD overlay

editor/src/Viewport/SceneViewportHudOverlay.cpp

@@ -0,0 +1,64 @@
+#include "SceneViewportHudOverlay.h"
+
+#include "SceneViewportOrientationGizmo.h"
+
+namespace XCEngine {
+namespace Editor {
+namespace {
+
+bool IsViewportRectValid(const ImVec2& viewportMin, const ImVec2& viewportMax) {
+    return viewportMax.x - viewportMin.x > 1.0f &&
+        viewportMax.y - viewportMin.y > 1.0f;
+}
+
+} // namespace
+
+void DrawSceneViewportHudOverlay(
+    ImDrawList* drawList,
+    const SceneViewportHudOverlayData& overlay,
+    const ImVec2& viewportMin,
+    const ImVec2& viewportMax) {
+    if (drawList == nullptr ||
+        !overlay.HasVisibleElements() ||
+        !IsViewportRectValid(viewportMin, viewportMax)) {
+        return;
+    }
+
+    drawList->PushClipRect(viewportMin, viewportMax, true);
+    if (overlay.showOrientationGizmo) {
+        DrawSceneViewportOrientationGizmo(
+            drawList,
+            overlay.sceneOverlay,
+            viewportMin,
+            viewportMax);
+    }
+    drawList->PopClipRect();
+}
+
+SceneViewportHudOverlayHitResult HitTestSceneViewportHudOverlay(
+    const SceneViewportHudOverlayData& overlay,
+    const ImVec2& viewportMin,
+    const ImVec2& viewportMax,
+    const ImVec2& mousePosition) {
+    SceneViewportHudOverlayHitResult result = {};
+    if (!overlay.HasVisibleElements() || !IsViewportRectValid(viewportMin, viewportMax)) {
+        return result;
+    }
+
+    if (overlay.showOrientationGizmo) {
+        const SceneViewportOrientationAxis axis = HitTestSceneViewportOrientationGizmo(
+            overlay.sceneOverlay,
+            viewportMin,
+            viewportMax,
+            mousePosition);
+        if (axis != SceneViewportOrientationAxis::None) {
+            result.kind = SceneViewportHudOverlayHitKind::OrientationAxis;
+            result.orientationAxis = axis;
+        }
+    }
+
+    return result;
+}
+
+} // namespace Editor
+} // namespace XCEngine