add spline snap

Source/Editor/SceneGraph/Actors/SplineNode.cs

@@ -7,6 +7,7 @@ using Real = System.Single;
 #endif
 
 using System;
+using System.Collections.Generic;
 using FlaxEditor.GUI.ContextMenu;
 using FlaxEditor.Modules;
 using FlaxEngine;
@@ -287,6 +288,10 @@ namespace FlaxEditor.SceneGraph.Actors
 
         private const Real PointNodeSize = 1.5f;
         private const Real TangentNodeSize = 1.0f;
+        private const Real SnapIndicatorSize = 1.7f;
+        private const Real SnapPointIndicatorSize = 2f;
+
+        private static Spline _currentEditSpline;
 
         /// <inheritdoc />
         public SplineNode(Actor actor)
@@ -298,6 +303,11 @@ namespace FlaxEditor.SceneGraph.Actors
 
         private unsafe void OnUpdate()
         {
+            if (Input.Keyboard.GetKey(KeyboardKeys.Shift))
+            {
+                EditSplineWithSnap();
+            }
+
             // Sync spline points with gizmo handles
             var actor = (Spline)Actor;
             var dstCount = actor.SplinePointsCount;
@@ -328,6 +338,56 @@ namespace FlaxEditor.SceneGraph.Actors
             }
         }
 
+        private void EditSplineWithSnap()
+        {
+            if (_currentEditSpline == null || _currentEditSpline != Actor)
+                return;
+
+            var selectedNode = SelectedSplineNode();
+            if (selectedNode == null)
+                return;
+
+            var selectedNodeBounds = new BoundingSphere(selectedNode.Transform.Translation, 1f);
+            var allSplinesInView = GetSplinesOnView();
+            allSplinesInView.Remove(_currentEditSpline);
+
+            if (allSplinesInView.Count == 0 || selectedNode == null)
+                return;
+
+            var snappedOnSplinePoint = false;
+            for (int i = 0; i < allSplinesInView.Count; i++)
+            {
+                for (int x = 0; x < allSplinesInView[i].SplineKeyframes.Length; x++)
+                {
+                    var keyframePosition = allSplinesInView[i].GetSplinePoint(x);
+                    var pointIndicatorSize = NodeSizeByDistance(keyframePosition, SnapPointIndicatorSize);
+                    var keyframeBounds = new BoundingSphere(keyframePosition, pointIndicatorSize);
+                    DebugDraw.DrawSphere(keyframeBounds, Color.Red, 0, false);
+
+                    if (keyframeBounds.Intersects(selectedNodeBounds))
+                    {
+                        _currentEditSpline.SetSplinePoint(selectedNode.Index, keyframeBounds.Center);
+                        snappedOnSplinePoint = true;
+                        break;
+                    }
+                }
+            }
+
+            if (!snappedOnSplinePoint)
+            {
+                var nearSplineSnapPoint = GetNearSplineSnapPosition(selectedNode.Transform.Translation, allSplinesInView);
+                var snapIndicatorSize = NodeSizeByDistance(nearSplineSnapPoint, SnapIndicatorSize);
+                var snapBounds = new BoundingSphere(nearSplineSnapPoint, snapIndicatorSize);
+
+                if (snapBounds.Intersects(selectedNodeBounds))
+                {
+                    _currentEditSpline.SetSplinePoint(selectedNode.Index, snapBounds.Center);
+                }
+
+                DebugDraw.DrawSphere(snapBounds, Color.Yellow, 0, true);
+            }
+        }
+
         /// <inheritdoc />
         public override void PostSpawn()
         {
@@ -396,6 +456,7 @@ namespace FlaxEditor.SceneGraph.Actors
 
         internal static void OnSplineEdited(Spline spline)
         {
+            _currentEditSpline = spline;
             var collider = spline.GetChild<SplineCollider>();
             if (collider && collider.Scene && collider.IsActiveInHierarchy && collider.HasStaticFlag(StaticFlags.Navigation) && !Editor.IsPlayMode)
             {
@@ -407,6 +468,60 @@ namespace FlaxEditor.SceneGraph.Actors
             }
         }
 
+        private static SplinePointNode SelectedSplineNode()
+        {
+            var selection = Editor.Instance.SceneEditing.Selection;
+            if (selection.Count != 1)
+                return null;
+            if (selection[0] is not SplineNode.SplinePointNode)
+                return null;
+
+            return (SplinePointNode)selection[0];
+        }
+
+        private static List<Spline> GetSplinesOnView()
+        {
+            var splines = Level.GetActors<Spline>();
+            var splinesOnView = new List<Spline>();
+
+            var viewTransform = Editor.Instance.Windows.EditWin.Viewport.ViewTransform;
+            var viewFov = Editor.Instance.Windows.EditWin.Viewport.FieldOfView;
+            var viewNear = Editor.Instance.Windows.EditWin.Viewport.NearPlane;
+            var viewFar = Editor.Instance.Windows.EditWin.Viewport.FarPlane;
+            var viewAspect = Editor.Instance.Windows.EditWin.Width / Editor.Instance.Windows.EditWin.Height;
+            var viewBounds = BoundingFrustum.FromCamera(viewTransform.Translation, viewTransform.Forward, viewTransform.Up, viewFov, viewNear, viewFar, viewAspect);
+
+            foreach (var s in splines)
+            {
+                var contains = viewBounds.Contains(s.EditorBox);
+                if (contains == ContainmentType.Contains || contains == ContainmentType.Intersects)
+                {
+                    splinesOnView.Add(s);
+                }
+            }
+
+            return splinesOnView;
+        }
+
+        private static Vector3 GetNearSplineSnapPosition(Vector3 position, List<Spline> splines)
+        {
+            var nearPoint = splines[0].GetSplinePointClosestToPoint(position);
+            var nearDistance = Vector3.Distance(nearPoint, position);
+
+            for (int i = 1; i < splines.Count; i++)
+            {
+                var point = splines[i].GetSplinePointClosestToPoint(position);
+                var distance = Vector3.Distance(point, position);
+                if (distance < nearDistance)
+                {
+                    nearPoint = point;
+                    nearDistance = distance;
+                }
+            }
+
+            return nearPoint;
+        }
+
         internal static Real NodeSizeByDistance(Vector3 nodePosition, Real nodeSize)
         {
             var cameraTransform = Editor.Instance.Windows.EditWin.Viewport.ViewportCamera.Viewport.ViewTransform;