Add heightfield geom type with Unity terrain, import not yet supported

unity/Runtime/Components/Shapes/MjHeightFieldShape.cs

@@ -0,0 +1,75 @@
+// 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.IO;
+using System.Linq;
+using System.Xml;
+using UnityEngine;
+
+namespace Mujoco
+{
+
+[Serializable]
+public class MjHeightFieldShape : IMjShape
+{
+
+  public Terrain terrain;
+
+  [Tooltip("The path, relative to Application.dataPath, where the heightmap data will be save in PNG format.")]
+  public string heightMapExportPath;
+
+  public string FullHeightMapPath => Path.GetFullPath(Path.Combine(Application.dataPath, heightMapExportPath));
+  public int HeightMapWidth => terrain.terrainData.heightmapTexture.width; 
+  public int HeightMapHeight => terrain.terrainData.heightmapTexture.height;
+  public Vector3 HeightMapScale => terrain.terrainData.heightmapScale;
+
+  public void ToMjcf(XmlElement mjcf, Transform transform)
+  {
+    ExportHeightMap();
+    var scene = MjScene.Instance;
+    var assetName = scene.GenerationContext.AddHeightFieldAsset(this);
+    mjcf.SetAttribute("hfield", assetName);
+  }
+
+  public void FromMjcf(XmlElement mjcf)
+  {
+
+  }
+
+  public void ExportHeightMap()
+  {
+    RenderTexture.active = terrain.terrainData.heightmapTexture;
+    Texture2D texture = new Texture2D(RenderTexture.active.width, RenderTexture.active.height);
+    texture.ReadPixels(new Rect(0, 0, RenderTexture.active.width, RenderTexture.active.height), 0, 0);
+    RenderTexture.active = null;
+    File.WriteAllBytes(FullHeightMapPath, texture.EncodeToPNG());
+  }
+
+
+  public Vector4 GetChangeStamp()
+  {
+    return Vector4.one;
+  }
+
+  public Tuple<Vector3[], int[]> BuildMesh()
+  {
+    return Tuple.Create(new Vector3[]{}, new int[]{});
+  }
+
+  public void DebugDraw(Transform transform)
+  {
+  }
+}
+}

unity/Runtime/Components/Shapes/MjHeightFieldShape.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 4572cd1b5f036db4483a214346587960
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

unity/Runtime/Components/Shapes/MjShapeComponent.cs

@@ -34,7 +34,8 @@ public abstract class MjShapeComponent : MjComponent {
     Cylinder,
     Box,
     Plane,
-    Mesh
+    Mesh,
+    HField
   }
 
   public ShapeTypes ShapeType;
@@ -46,6 +47,7 @@ public abstract class MjShapeComponent : MjComponent {
   public MjEllipsoidShape Ellipsoid = new MjEllipsoidShape();
   public MjPlaneShape Plane = new MjPlaneShape();
   public MjMeshShape Mesh = new MjMeshShape();
+  public MjHeightFieldShape HField = new MjHeightFieldShape();
 
   public IMjShape Shape {
     get {
@@ -58,6 +60,7 @@ public abstract class MjShapeComponent : MjComponent {
         case ShapeTypes.Box: return Box;
         case ShapeTypes.Plane: return Plane;
         case ShapeTypes.Mesh: return Mesh;
+        case ShapeTypes.HField: return HField;
       }
     }
   }