122 lines
3.6 KiB
C#
122 lines
3.6 KiB
C#
using Godot;
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using System;
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using System.Collections.Generic;
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public class Train : Spatial
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{
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[Export]
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private float _speed = 1.0f;
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[Export]
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private NodePath _railwayPath;
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private Railway _railway;
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private float _distance = 0;
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[Export]
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private NodePath _carPath;
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private TrainCar _car;
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private Spatial[] _bogies;
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private readonly Dictionary<Spatial, PathFollow> _bogiePathFollows = new Dictionary<Spatial, PathFollow>();
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private ImmediateGeometry _imgui;
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// Called when the node enters the scene tree for the first time.
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public override void _Ready()
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{
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_imgui = new ImmediateGeometry();
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var m = new SpatialMaterial();
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m.VertexColorUseAsAlbedo = true;
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m.FlagsUnshaded = true;
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_imgui.MaterialOverride = m;
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AddChild(_imgui);
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_railway = GetNode<Railway>(_railwayPath);
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_car = GetNode<TrainCar>(_carPath);
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_bogies = new Spatial[_car.Bogies.Length];
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for (int i = 0; i < _bogies.Length; i++)
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{
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var b = _car.Bogies[i];
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_bogies[i] = b;
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_bogiePathFollows[b] = new PathFollow
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{
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RotationMode = PathFollow.RotationModeEnum.Oriented
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};
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_railway.AddPathFollower(_bogiePathFollows[b]);
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// detach the bogies from the car as we need to set the bogie
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// positions in order to calculate the car position and it will
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// get confusing if they're in a parent/child relationship,
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// so make them all siblings
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_car.RemoveChild(b);
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this.AddChild(b);
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}
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}
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// Called every frame. 'delta' is the elapsed time since the previous frame.
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public override void _Process(float delta)
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{
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var length = _railway.Curve.GetBakedLength();
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// first determine which is the front bogie. this is dependent
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// on the direction of travel.
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int travelDir = (int)(_distance / length) == 0 ? -1 : 1;
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DrawTravelDirectionIndicator(travelDir);
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// keep track of total distance
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_distance += delta * _speed;
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// wrap at 2x total distance
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_distance %= length * 2;
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var distance = PingPong(_distance, length);
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// get the position of the first bogie on the track
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var b = _bogies[0];
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var pathFollow = _bogiePathFollows[b];
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pathFollow.Offset = distance;
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b.Translation = pathFollow.Translation;
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b.Rotation = pathFollow.Rotation;
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// now we want to position the car over the first bogie
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GD.Print(_car.Wheelbase);
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_car.Translation = b.Translation;
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_car.Rotation = b.Rotation;
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// TODO: this rotation quat needs to position the other
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// bogie over the curve
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_car.Translation += _car.Transform.basis
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.RotationQuat()
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.Xform(Vector3.Back) * _car.Wheelbase * 0.5f;
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}
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private void DrawTravelDirectionIndicator(int travelDir)
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{
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_imgui.Clear();
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_imgui.Begin(Mesh.PrimitiveType.LineStrip);
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_imgui.SetColor(new Color(1, 0, 0));
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var c = _car.Translation + Vector3.Up * 2;
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_imgui.AddVertex(c);
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var d = travelDir;
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var l = 5;
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var e = c + _car.Transform.basis
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.RotationQuat()
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.Xform(Vector3.Forward) * d * l;
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_imgui.AddVertex(e);
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_imgui.End();
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}
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// poor mans branching ping pong
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private float PingPong(float t, float length)
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{
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var tml = t % length;
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return t > length
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? length - tml
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: tml;
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}
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}
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