Fix snap to the ground to use scene graph query instead of physics only raycast

Source/Editor/Gizmo/GizmoBase.cs

@@ -80,6 +80,13 @@ namespace FlaxEditor.Gizmo
         {
         }
 
+        /// <summary>
+        /// Performs scene objects snapping to the ground.
+        /// </summary>
+        public virtual void SnapToGround()
+        {
+        }
+
         /// <summary>
         /// Draws the gizmo.
         /// </summary>

Source/Editor/Gizmo/IGizmoOwner.cs

@@ -89,5 +89,10 @@ namespace FlaxEditor.Gizmo
         /// Gets a <see cref="FlaxEditor.Undo"/> object used by the gizmo owner.
         /// </summary>
         Undo Undo { get; }
+
+        /// <summary>
+        /// Gets the root tree node for the scene graph.
+        /// </summary>
+        SceneGraph.RootNode SceneGraphRoot { get; }
     }
 }

Source/Editor/Gizmo/TransformGizmo.cs

@@ -218,6 +218,12 @@ namespace FlaxEditor.Gizmo
             }
         }
 
+        /// <inheritdoc />
+        protected override bool IsSelected(SceneGraphNode obj)
+        {
+            return _selection.Contains(obj);
+        }
+
         /// <inheritdoc />
         protected override void OnApplyTransformation(ref Vector3 translationDelta, ref Quaternion rotationDelta, ref Vector3 scaleDelta)
         {

Source/Editor/Gizmo/TransformGizmoBase.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using FlaxEditor.SceneGraph;
 using FlaxEngine;
 
 namespace FlaxEditor.Gizmo
@@ -398,15 +399,7 @@ namespace FlaxEditor.Gizmo
             // Snap to ground
             if (_activeAxis == Axis.None && SelectionCount != 0 && Owner.SnapToGround)
             {
-                if (Physics.RayCast(Position, Vector3.Down, out var hit, float.MaxValue, uint.MaxValue, false))
+                SnapToGround();
-                {
-                    StartTransforming();
-                    var translationDelta = hit.Point - Position;
-                    var rotationDelta = Quaternion.Identity;
-                    var scaleDelta = Vector3.Zero;
-                    OnApplyTransformation(ref translationDelta, ref rotationDelta, ref scaleDelta);
-                    EndTransforming();
-                }
             }
             // Only when is active
             else if (_isActive)
@@ -517,6 +510,39 @@ namespace FlaxEditor.Gizmo
             UpdateMatrices();
         }
 
+        /// <inheritdoc />
+        public override void SnapToGround()
+        {
+            if (Owner.SceneGraphRoot == null)
+                return;
+            var ray = new Ray(Position, Vector3.Down);
+            while (true)
+            {
+                var view = new Ray(Owner.ViewPosition, Owner.ViewDirection);
+                var rayCastFlags = SceneGraphNode.RayCastData.FlagTypes.SkipEditorPrimitives;
+                var hit = Owner.SceneGraphRoot.RayCast(ref ray, ref view, out var distance, out _, rayCastFlags);
+                if (hit != null)
+                {
+                    // Skip snapping selection to itself
+                    if (IsSelected(hit))
+                    {
+                        GetSelectedObjectsBounds(out var selectionBounds, out _);
+                        ray.Position = ray.GetPoint(selectionBounds.Size.Y * 0.5f);
+                        continue;
+                    }
+
+                    // Snap
+                    StartTransforming();
+                    var translationDelta = ray.GetPoint(distance) - Position;
+                    var rotationDelta = Quaternion.Identity;
+                    var scaleDelta = Vector3.Zero;
+                    OnApplyTransformation(ref translationDelta, ref rotationDelta, ref scaleDelta);
+                    EndTransforming();
+                }
+                break;
+            }
+        }
+
         /// <summary>
         /// Gets a value indicating whether this tool can transform objects.
         /// </summary>
@@ -545,6 +571,13 @@ namespace FlaxEditor.Gizmo
         /// <param name="navigationDirty">True if editing the selected objects transformations marks the navigation system area dirty (for auto-rebuild), otherwise skip update.</param>
         protected abstract void GetSelectedObjectsBounds(out BoundingBox bounds, out bool navigationDirty);
 
+        /// <summary>
+        /// Checks if the specified object is selected.
+        /// </summary>
+        /// <param name="obj">The object to check.</param>
+        /// <returns>True if it's selected, otherwise false.</returns>
+        protected abstract bool IsSelected(SceneGraphNode obj);
+
         /// <summary>
         /// Called when user starts transforming selected objects.
         /// </summary>

Source/Editor/Tools/Foliage/EditFoliageGizmo.cs

@@ -2,6 +2,7 @@
 
 using System;
 using FlaxEditor.Gizmo;
+using FlaxEditor.SceneGraph;
 using FlaxEditor.Tools.Foliage.Undo;
 using FlaxEngine;
 
@@ -87,6 +88,12 @@ namespace FlaxEditor.Tools.Foliage
             navigationDirty = false;
         }
 
+        /// <inheritdoc />
+        protected override bool IsSelected(SceneGraphNode obj)
+        {
+            return false;
+        }
+
         /// <inheritdoc />
         protected override void OnStartTransforming()
         {
@@ -231,6 +238,21 @@ namespace FlaxEditor.Tools.Foliage
             Owner.Undo?.AddAction(action);
         }
 
+        /// <inheritdoc />
+        public override void SnapToGround()
+        {
+            if (Physics.RayCast(Position, Vector3.Down, out var hit, float.MaxValue, uint.MaxValue, false))
+            {
+                // Snap
+                StartTransforming();
+                var translationDelta = hit.Point - Position;
+                var rotationDelta = Quaternion.Identity;
+                var scaleDelta = Vector3.Zero;
+                OnApplyTransformation(ref translationDelta, ref rotationDelta, ref scaleDelta);
+                EndTransforming();
+            }
+        }
+
         /// <inheritdoc />
         public override void OnActivated()
         {

Source/Editor/Viewport/EditorGizmoViewport.cs

@@ -21,10 +21,12 @@ namespace FlaxEditor.Viewport
         /// </summary>
         /// <param name="task">The task.</param>
         /// <param name="undo">The undo.</param>
-        public EditorGizmoViewport(SceneRenderTask task, Undo undo)
+        /// <param name="sceneGraphRoot">The scene graph root.</param>
+        public EditorGizmoViewport(SceneRenderTask task, Undo undo, SceneGraph.RootNode sceneGraphRoot)
         : base(task, new FPSCamera(), true)
         {
             Undo = undo;
+            SceneGraphRoot = sceneGraphRoot;
 
             SetUpdate(ref _update, OnUpdate);
         }
@@ -73,6 +75,9 @@ namespace FlaxEditor.Viewport
         /// <inheritdoc />
         public Undo Undo { get; }
 
+        /// <inheritdoc />
+        public SceneGraph.RootNode SceneGraphRoot { get; }
+
         /// <inheritdoc />
         protected override bool IsControllingMouse => Gizmos.Active?.IsControllingMouse ?? false;
 

Source/Editor/Viewport/MainEditorGizmoViewport.cs

@@ -184,7 +184,7 @@ namespace FlaxEditor.Viewport
         /// </summary>
         /// <param name="editor">Editor instance.</param>
         public MainEditorGizmoViewport(Editor editor)
-        : base(Object.New<SceneRenderTask>(), editor.Undo)
+        : base(Object.New<SceneRenderTask>(), editor.Undo, editor.Scene.Root)
         {
             _editor = editor;
             _dragAssets = new DragAssets<DragDropEventArgs>(ValidateDragItem);

Source/Editor/Viewport/PrefabWindowViewport.cs

@@ -336,6 +336,9 @@ namespace FlaxEditor.Viewport
         /// <inheritdoc />
         public Undo Undo { get; }
 
+        /// <inheritdoc />
+        public RootNode SceneGraphRoot => _window.Graph.Root;
+
         /// <inheritdoc />
         public EditorViewport Viewport => this;