make train go back n forth

scenes/RailNode.tscn

@@ -1,22 +0,0 @@
-[gd_scene load_steps=2 format=2]
-
-[sub_resource type="CSharpScript" id=1]
-script/source = "using Godot;
-using System;
-
-public class RailNode : Spatial
-{
-    public override void _Ready()
-    {
-
-    }
-
-//  public override void _Process(float delta)
-//  {
-//
-//  }
-}
-"
-
-[node name="Spatial" type="Spatial"]
-script = SubResource( 1 )

scenes/Railway.tscn

@@ -1,23 +1,30 @@
-[gd_scene load_steps=4 format=2]
+[gd_scene load_steps=3 format=2]
 
 [ext_resource path="res://scripts/Railway.cs" type="Script" id=1]
 
 [sub_resource type="Curve3D" id=1]
+bake_interval = 0.01
 _data = {
-"points": PoolVector3Array( 0, 0, 0, 0, 0, 0, 8.10688, -1.81506, 7.57791, 0, 0, 0, 0, 0, 0, -4.46766, -3.67929, 0.175438, 0, 0, 0, 0, 0, 0, -6.79476, 2.00362, -6.79993, 0, 0, 0, 0, 0, 0, 5.56111, 6.33345, -1.84912, 0, 0, 0, 0, 0, 0, 11.2517, 3.50708, 4.91382, 0, 0, 0, 0, 0, 0, 14.9168, -0.251479, 11.0718 ),
+"points": PoolVector3Array( -2.68413, 0, -1.21546, 2.68413, 0, 1.21546, -20.005, 0, -8.27961, -0.202576, 0, -2.12705, 0.202576, 0, 2.12705, -15.5484, 0.00448608, -2.35426, -1.06352, 0, -2.88671, 1.06352, 0, 2.88671, -16.1055, 0.000946045, 5.85007, -3.24122, 0, 0.202576, 3.24122, 0, -0.202576, -8.81272, 0, 10.4587, -0.468547, 0, 2.85805, 0.468547, 0, -2.85805, -3.58364, -0.000244141, 4.56199, -1.17756, 0, 3.41513, 1.17756, 0, -3.41513, -5.10296, -0.000259399, -3.5917, -2.78542, 0, -1.56996, 2.78542, 0, 1.56996, 3.2912, -0.000259399, -6.30449, -3.70976, 0, -1.39605, 3.70976, 0, 1.39605, 9.68509, -0.000259399, -0.0972629, 0, 0, 0, 0, 0, 0, 19.9658, -0.000259399, -1.11014 ),
-"tilts": PoolRealArray( 0, 0, 0, 0, 0, 0 )
+"tilts": PoolRealArray( 0, 0, 0, 0, 0, 0, 0, 0, 0 )
 }
 
-[sub_resource type="SpatialMaterial" id=2]
+[node name="Railway" type="Spatial"]
-flags_unshaded = true
-vertex_color_use_as_albedo = true
-
-[node name="Railway" type="Path"]
-curve = SubResource( 1 )
 script = ExtResource( 1 )
-_color = Color( 0, 1, 0.133333, 1 )
 
-[node name="ImmediateGeometry" type="ImmediateGeometry" parent="."]
+[node name="Path" type="Path" parent="."]
-material_override = SubResource( 2 )
+curve = SubResource( 1 )
 
-[connection signal="curve_changed" from="." to="." method="OnPathCurveChanged"]
+[node name="CSGPolygon" type="CSGPolygon" parent="."]
+snap = 0.01
+polygon = PoolVector2Array( -0.0540804, -0.000681907, -0.0495726, 0.0487114, 0.0444932, 0.0509578, 0.0464191, 0.000881314 )
+mode = 2
+path_node = NodePath("../Path")
+path_interval_type = 1
+path_interval = 0.01
+path_simplify_angle = 0.2
+path_rotation = 2
+path_local = false
+path_continuous_u = true
+path_u_distance = 1.0
+path_joined = false

scenes/Train.tscn

@@ -2,11 +2,10 @@
 
 [ext_resource path="res://scripts/Train.cs" type="Script" id=1]
 
-[node name="Train" type="Node"]
+[node name="Train" type="Spatial"]
 script = ExtResource( 1 )
 
 [node name="CSGBox" type="CSGBox" parent="."]
-transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0.5, 0 )
 width = 1.0
 height = 1.0
 depth = 4.0

scripts/Railway.cs

@@ -1,53 +1,34 @@
 using Godot;
 using System;
 
-[Tool]
+public class Railway : Node
-public class Railway : Path
 {
-    [Export]
+    private Path _path = null;
-    private Color _color;
+    private Path Path
-    
-    [Export]
-    private float _gauge = 1f;
-    
-    private ImmediateGeometry _geo = null;
-    private Vector3[] _points = null;
-    
-    public void OnPathCurveChanged() 
     {
-        Curve.Tessellate();
+        get
-        _points = Curve.GetBakedPoints();
+        {
+            if (_path == null)
+            {
+                _path = GetNode<Path>("Path");
             }
+            return _path;
+        }
+    }
+
+    public Curve3D Curve => Path.Curve;
 
     // Called when the node enters the scene tree for the first time.
     public override void _Ready()
     {
-        base._Ready();
-        
-        _geo = GetNode<ImmediateGeometry>("ImmediateGeometry");
-        
-        var m = new SpatialMaterial();
-        m.VertexColorUseAsAlbedo = true;
-        m.FlagsUnshaded = true;
-        _geo.MaterialOverride = m;
-
-        OnPathCurveChanged();
     }
 
     public override void _Process(float delta)
     {
-        base._Process(delta);
+    }
 
-        if (_geo == null) return;
+    public void AddPathFollower(PathFollow pathFollow)
-        if (_points == null || _points.Length == 0) return;
-        
-        _geo.Clear();
-        _geo.Begin(Mesh.PrimitiveType.LineStrip);
-        _geo.SetColor(new Color(1, 0, 0));
-        for(int i = 0; i < _points.Length; i++)
     {
-            _geo.AddVertex(_points[i]);
+        Path.AddChild(pathFollow);
-        }
-        _geo.End();
     }
 }

scripts/Train.cs

@@ -1,16 +1,52 @@
 using Godot;
 using System;
 
-public class Train : Node
+public class Train : Spatial
 {
+    [Export]
+    private float _speed = 1.0f;
+
+    [Export]
+    private NodePath _railwayPath;
+
+    private Railway _railway;
+    private readonly PathFollow _pathFollow = new PathFollow
+    {
+        RotationMode = PathFollow.RotationModeEnum.Oriented
+    };
+    private float _distance = 0;
+
     // Called when the node enters the scene tree for the first time.
     public override void _Ready()
     {
+        _railway = GetNode<Railway>(_railwayPath) as Railway;
+        _railway.AddPathFollower(_pathFollow);
     }
 
-//  // Called every frame. 'delta' is the elapsed time since the previous frame.
+    // Called every frame. 'delta' is the elapsed time since the previous frame.
-//  public override void _Process(float delta)
+    public override void _Process(float delta)
-//  {
+    {
-//      
+        var length = _railway.Curve.GetBakedLength();
-//  }
+
+        // keep track of total distance
+        _distance += delta * _speed;
+        // wrap at 2x total distance
+        _distance %= length * 2;
+
+        var distance = PingPong(_distance, length);
+
+        _pathFollow.Offset = distance;
+        Translation = _pathFollow.Translation;
+        Rotation = _pathFollow.Rotation;
+    }
+
+    // poor mans branching ping pong
+    private float PingPong(float t, float length)
+    {
+        var tml = t % length;
+
+        return t > length
+            ? length - tml
+            : tml;
+    }
 }