Initial release of the Unity plugin.

PiperOrigin-RevId: 425947505

unity/Runtime/Components/MjSphereShape.cs

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+// Copyright 2019 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using System.Linq;
+using System.Xml;
+using UnityEngine;
+
+namespace Mujoco {
+
+[Serializable]
+public class MjSphereShape : IMjShape {
+  public float Radius = 0.5f;
+  private const float _scaleTolerance = 1e-6f;
+
+  public void ToMjcf(XmlElement mjcf, Transform transform) {
+    if (Math.Abs(transform.lossyScale.x - transform.lossyScale.y) > _scaleTolerance ||
+        Math.Abs(transform.lossyScale.y - transform.lossyScale.z) > _scaleTolerance) {
+      Debug.LogWarning(
+          $"{transform.name}: Sphere shapes work only with uniform scaling. Using the value of X" +
+          " component.\n Consider using Ellipsoid shape if you want to use non-uniform scaling.",
+          transform);
+    }
+    mjcf.SetAttribute("size", $"{Radius * transform.lossyScale.x}");
+  }
+
+  public void FromMjcf(XmlElement mjcf) {
+    var values = mjcf.GetFloatArrayAttribute("size", defaultValue: new float[] { 0.5f });
+    Radius = values[0];
+  }
+
+  public Tuple<Vector3[], int[]> BuildMesh() {
+    return MeshGenerators.BuildSphere(scale: Vector3.one * Radius);
+  }
+
+  public Vector4 GetChangeStamp() {
+    return new Vector4(Radius, 1, 1, 0);
+  }
+
+  public void DebugDraw(Transform transform) {
+    Gizmos.DrawWireSphere(transform.position, Radius * transform.lossyScale.x);
+  }
+}
+}