Add support for fluid shapes to Unity plugin

unity/Runtime/Components/Shapes/MjGeomSettings.cs

@@ -22,6 +22,10 @@ namespace Mujoco {
 [Serializable]
 public struct MjGeomSettings {
 
+  public enum FluidShapeTypes {
+    None,
+    Ellipsoid,
+  }
 
   [Tooltip("Priority")]
   public int Priority;
@@ -35,11 +39,15 @@ public struct MjGeomSettings {
   [Tooltip("Contact friction parameters for dynamically generated contact pairs.")]
   public GeomFriction Friction;
 
+  [Tooltip("Shape used for fluid simulation.")]
+  public FluidShapeTypes FluidShapeType;
+
   // Default geom settings.
   public static MjGeomSettings Default = new MjGeomSettings() {
     Solver = GeomSolver.Default,
     Filtering = CollisionFiltering.Default,
-    Friction = GeomFriction.Default
+    Friction = GeomFriction.Default,
+    FluidShapeType = FluidShapeTypes.None
   };
 
   public void FromMjcf(XmlElement mjcf) {
@@ -76,6 +84,10 @@ public struct MjGeomSettings {
     Friction.Sliding = friction[0];
     Friction.Torsional = friction[1];
     Friction.Rolling = friction[2];
+
+    // Fluid shape settings.
+    FluidShapeType = mjcf.GetEnumAttribute<FluidShapeTypes>(
+        "fluidshape", FluidShapeTypes.None, ignoreCase: true);
   }
 
   public void ToMjcf(XmlElement mjcf) {
@@ -97,6 +109,9 @@ public struct MjGeomSettings {
 
     // Inertia and friction settings.
     mjcf.SetAttribute("friction", MjEngineTool.MakeLocaleInvariant($"{Friction.Sliding} {Friction.Torsional} {Friction.Rolling}"));
+
+    // Fluid shape settings.
+    mjcf.SetAttribute("fluidshape", FluidShapeType.ToString().ToLower());
   }
 }
 

unity/Tests/Editor/Components/MjGeomSettingsTests.cs

@@ -109,6 +109,13 @@ public class MjGeomSettingsGenerationTests {
     _settings.ToMjcf(_mjcf);
     Assert.That(_doc.OuterXml, Does.Contain(@"friction=""5 6 7"""));
   }
+
+  [Test]
+  public void FluidShapeTypeMjcf() {
+    _settings.FluidShapeType = MjGeomSettings.FluidShapeTypes.Ellipsoid;
+    _settings.ToMjcf(_mjcf);
+    Assert.That(_doc.OuterXml, Does.Contain(@"fluidshape=""ellipsoid"""));
+  }
 }
 
 [TestFixture]
@@ -199,5 +206,14 @@ public class MjGeomSettingsParsingTests {
     Assert.That(_settings.Friction.Torsional, Is.EqualTo(6));
     Assert.That(_settings.Friction.Rolling, Is.EqualTo(7));
   }
+
+  [Test]
+  public void FluidShapeTypeMjcf() {
+    _mjcf.SetAttribute("fluidshape", "ellipsoid");
+    _settings.FromMjcf(_mjcf);
+    Assert.That(_settings.FluidShapeType, Is.EqualTo(
+        MjGeomSettings.FluidShapeTypes.Ellipsoid
+    ));
+  }
 }
 }