ported from perforce

DonkeysAndDroids.Godot/CorruptionArea.cs

@@ -0,0 +1,68 @@
+using Godot;
+
+public partial class CorruptionArea : Node3D
+{
+    public override void _Ready()
+    {
+        _disc = GetNode<MeshInstance3D>("Disc");
+        if (_disc == null)
+        {
+            GD.PushWarning("CorruptionArea: Could not find child MeshInstance3D named 'Disc'.");
+            return;
+        }
+
+        _baseScale = _disc.Scale;
+        ApplyRadius();
+
+        _shaderMaterial = (ShaderMaterial)_disc.GetActiveMaterial(0).Duplicate();
+        _disc.MaterialOverride = _shaderMaterial;
+    }
+
+    public override void _Process(double delta)
+    {
+        if (_shaderMaterial == null)
+            return;
+
+        var t = Time.GetTicksMsec() / 1000.0f;
+        var pulse = 1.0f + Mathf.Sin(t * PulseSpeed) * PulseAmount;
+
+        _shaderMaterial.SetShaderParameter("u_pulse", pulse);
+        _shaderMaterial.SetShaderParameter("base_color", Color);
+    }
+
+    /// <summary>
+    ///     Call this if you change Radius at runtime.
+    /// </summary>
+    public void ApplyRadius()
+    {
+        if (_disc == null)
+            return;
+
+        var r = Mathf.Max(Radius, 0.01f);
+        // PlaneMesh is 2x2 units, so scale XZ by radius to get the desired world radius.
+        _disc.Scale = new(_baseScale.X * r, _baseScale.Y, _baseScale.Z * r);
+    }
+
+    public void SetRadius(float radius)
+    {
+        Radius = radius;
+        ApplyRadius();
+    }
+
+    [Export]
+    public float Radius { get; set; } = 1.0f; // World-space radius in XZ units.
+
+    [Export]
+    public float PulseSpeed { get; set; } = 1.5f;
+
+    [Export]
+    public float PulseAmount { get; set; } = 0.25f;
+
+    [Export]
+    public Color Color { get; set; } = new(0.6f, 0.1f, 0.8f, 0.45f);
+
+    private Vector3 _baseScale = Vector3.One;
+
+    private MeshInstance3D _disc;
+    private ShaderMaterial _shaderMaterial;
+}