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

unity/Editor/Components/MjShapeComponentEditor.cs

@@ -30,7 +30,7 @@ public class MjShapeComponentEditor : Editor {
     var shapeType = serializedObject.FindProperty("ShapeType");
     EditorGUILayout.PropertyField(shapeType);
     EditorGUILayout.PropertyField(
-        serializedObject.FindProperty($"{shapeType.enumDisplayNames[shapeType.enumValueIndex]}"),
+        serializedObject.FindProperty($"{shapeType.enumNames[shapeType.enumValueIndex]}"),
         includeChildren: true);
     serializedObject.ApplyModifiedProperties();
   }

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;
       }
     }
   }

unity/Runtime/Tools/MjcfGenerationContext.cs

@@ -34,6 +34,7 @@ public class MjcfGenerationContext {
   private int _nuserSensor;
   private int _numGeneratedNames = 0;
   private Dictionary<Mesh, string> _meshAssets = new Dictionary<Mesh, string>();
+  private Dictionary<MjHeightFieldShape, string> _hFieldAssets = new Dictionary<MjHeightFieldShape, string>();
 
   public void GenerateMjcf(XmlElement mjcf) {
     GenerateConfigurationMjcf(mjcf);
@@ -51,6 +52,17 @@ public class MjcfGenerationContext {
     return _meshAssets[mesh];
   }
   
+  // Adds a mesh to the list of assets that will be added to the generated MJCF.
+  // Returns the unique name that identifies this new asset.
+  public string AddHeightFieldAsset(MjHeightFieldShape hField) {
+    if (!_hFieldAssets.ContainsKey(hField)) {
+      var uniqueName = $"hfield_{_numGeneratedNames}";
+      _numGeneratedNames++;
+      _hFieldAssets.Add(hField, uniqueName);
+    }
+    return _hFieldAssets[hField];
+  }
+
   public string GenerateName(Component comp) {
     var settings = MjGlobalSettings.Instance;
     if (settings?.UseRawGameObjectNames ?? false) {
@@ -81,10 +93,15 @@ public class MjcfGenerationContext {
   private void GenerateAssetsMjcf(XmlElement mjcf) {
     var doc = mjcf.OwnerDocument;
     var assetMjcf = (XmlElement)mjcf.AppendChild(doc.CreateElement("asset"));
-    foreach (var asset in _meshAssets) {
+    foreach (var meshAsset in _meshAssets) {
       var meshMjcf = (XmlElement)assetMjcf.AppendChild(doc.CreateElement("mesh"));
-      meshMjcf.SetAttribute("name", asset.Value);
+      meshMjcf.SetAttribute("name", meshAsset.Value);
-      GenerateMeshMjcf(asset.Key, meshMjcf);
+      GenerateMeshMjcf(meshAsset.Key, meshMjcf);
+    }
+   foreach (var hFieldAsset in _hFieldAssets) {
+      var hFieldMjcf = (XmlElement)assetMjcf.AppendChild(doc.CreateElement("hfield"));
+      hFieldMjcf.SetAttribute("name", hFieldAsset.Value);
+      GenerateHeightFieldMjcf(hFieldAsset.Key, hFieldMjcf);
     }
   }
 
@@ -97,5 +114,15 @@ public class MjcfGenerationContext {
     }
     mjcf.SetAttribute("vertex", vertexPositionsStr.ToString());
   }
+  
+  private static void GenerateHeightFieldMjcf(MjHeightFieldShape hFieldComponent, XmlElement mjcf) {
+    mjcf.SetAttribute("nrow", "0");
+    mjcf.SetAttribute("ncol", "0");
+    mjcf.SetAttribute("content_type", "image/png");
+    mjcf.SetAttribute("file", hFieldComponent.FullHeightMapPath);
+            
+    mjcf.SetAttribute("size", MjEngineTool.MakeLocaleInvariant($"{hFieldComponent.HeightMapScale.x*hFieldComponent.HeightMapHeight/2} {hFieldComponent.HeightMapScale.z * hFieldComponent.HeightMapWidth/2} {hFieldComponent.HeightMapScale.y*2} {hFieldComponent.terrain.transform.position.y}"));
+
+  }
 }
 }