refactor: Use gp_Ax2 for camera plane orientation

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

src/Camera.cpp

@@ -6,7 +6,8 @@
 //     - use a right-handed, Z-up coordinate system to match Open CASCADE
 
 #include "Camera.h"
-#include "ViewportWidget.h"
+#include <gp_Ax2.hxx>
+#include <gp_Dir.hxx>
 #include <QApplication>
 #include <QWheelEvent>
 #include <QPropertyAnimation>
@@ -202,25 +203,28 @@ void Camera::restoreState()
     setZoom(m_savedZoom);
 }
 
-void Camera::animateToPlaneView(int plane)
+void Camera::animateToPlaneView(const gp_Ax2& plane)
 {
-    float targetXRot = xRotation();
-    float targetYRot = yRotation();
-    switch (static_cast<ViewportWidget::SketchPlane>(plane)) {
-        case ViewportWidget::SketchPlane::XY: // Top view
-            targetXRot = 90 * 16;
-            targetYRot = 0;
-            break;
-        case ViewportWidget::SketchPlane::XZ: // Front view
-            targetXRot = 0;
-            targetYRot = 0;
-            break;
-        case ViewportWidget::SketchPlane::YZ: // Right view
-            targetXRot = 0;
-            targetYRot = -90 * 16;
-            break;
-        case ViewportWidget::SketchPlane::NONE:
-            break;
+    const auto& normal = plane.Direction();
+    QVector3D n(normal.X(), normal.Y(), normal.Z());
+    QVector3D d;
+
+    // This logic preserves the quirky view directions of the original implementation.
+    // For XZ-like planes (normal is mostly along Y), the view is aligned WITH the plane normal.
+    // For other planes, it's aligned AGAINST the normal.
+    if (qAbs(n.y()) > 0.99) {
+        d = n;
+    } else {
+        d = -n;
+    }
+
+    float targetXRot = qRadiansToDegrees(asin(-d.z())) * 16.0f;
+    float targetYRot;
+
+    if (qAbs(d.z()) > 0.9999) { // Top/bottom-like view, Y rotation is arbitrary
+        targetYRot = 0; // Set to 0 for stability
+    } else {
+        targetYRot = qRadiansToDegrees(atan2(d.x(), d.y())) * 16.0f;
     }
 
     auto* animGroup = new QParallelAnimationGroup(this);

src/Camera.h

@@ -14,6 +14,8 @@
 #include <QMouseEvent>
 #include <QWheelEvent>
 
+#include <gp_Ax2.hxx>
+
 class Camera : public QObject
 {
     Q_OBJECT
@@ -46,7 +48,7 @@ public:
     void saveState();
     void restoreState();
 
-    void animateToPlaneView(int plane);
+    void animateToPlaneView(const gp_Ax2& plane);
     void animateRestoreState();
     void animateToHomeView();