Fix Oculus Mixed Reality Capture Camera pose (#80)

* Fixing Oculus MRC pose

* Updating style

Assets/Scripts/OculusMRCCameraUpdate.cs

@@ -0,0 +1,88 @@
+// Copyright 2021 The Open Brush Authors
+//
+// 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 UnityEngine;
+
+using Node = UnityEngine.XR.XRNode;
+using NodeState = UnityEngine.XR.XRNodeState;
+
+#if OCULUS_SUPPORTED
+
+namespace TiltBrush {
+
+public class OculusMRCCameraUpdate : MonoBehaviour {
+
+  private OVRPose? calibratedCameraPose = null;
+
+  void Update() {
+    if (!calibratedCameraPose.HasValue) {
+      if (!OVRPlugin.Media.GetInitialized()) {
+        return;
+      }
+
+      OVRPlugin.CameraIntrinsics cameraIntrinsics;
+      OVRPlugin.CameraExtrinsics cameraExtrinsics;
+
+      if (OVRPlugin.GetMixedRealityCameraInfo(0, out cameraExtrinsics, out cameraIntrinsics)) {
+        calibratedCameraPose = cameraExtrinsics.RelativePose.ToOVRPose();
+      } else {
+        return;
+      }
+    }
+
+    OVRPose cameraStagePoseInUnits = calibratedCameraPose.Value;
+
+    // Converting position from meters to decimeters (unit used by Open Brush)
+    cameraStagePoseInUnits.position *= App.METERS_TO_UNITS;
+
+    // Workaround to fix the OVRExtensions.ToWorldSpacePose() and 
+    // OVRComposition.ComputeCameraWorldSpacePose() calls when computing 
+    // the Mixed Reality foreground and background camera positions.
+    OVRPose headPose = OVRPose.identity;
+
+    Vector3 pos;
+    Quaternion rot;
+
+    if (OVRNodeStateProperties.GetNodeStatePropertyVector3(Node.Head, 
+        NodeStatePropertyType.Position, OVRPlugin.Node.Head, OVRPlugin.Step.Render, out pos)) {
+      headPose.position = pos;
+    }
+
+    if (OVRNodeStateProperties.GetNodeStatePropertyQuaternion(Node.Head, 
+        NodeStatePropertyType.Orientation, OVRPlugin.Node.Head, OVRPlugin.Step.Render, out rot)) {
+      headPose.orientation = rot;
+    }
+
+    OVRPose headPoseInUnits = OVRPose.identity;
+    headPoseInUnits.position = headPose.position * App.METERS_TO_UNITS;
+    headPoseInUnits.orientation = headPose.orientation;
+
+    OVRPose stageToLocalPose = OVRPlugin.GetTrackingTransformRelativePose(
+        OVRPlugin.TrackingOrigin.Stage).ToOVRPose();
+
+    OVRPose stageToLocalPoseInUnits = OVRPose.identity;
+    stageToLocalPoseInUnits.position = stageToLocalPose.position * App.METERS_TO_UNITS;
+    stageToLocalPoseInUnits.orientation = stageToLocalPose.orientation;
+
+    OVRPose cameraWorldPoseInUnits = headPoseInUnits.Inverse() * stageToLocalPoseInUnits * 
+        cameraStagePoseInUnits;
+    OVRPose cameraStagePoseFix = stageToLocalPose.Inverse() * headPose * cameraWorldPoseInUnits;
+
+    // Override the MRC camera's stage pose
+    OVRPlugin.OverrideExternalCameraStaticPose(0, true, cameraStagePoseFix.ToPosef());        
+  }
+}
+} // namespace TiltBrush
+
+#endif // OCULUS_SUPPORTED

Assets/Scripts/VrSdk.cs

@@ -183,6 +183,8 @@ void Awake() {
       // adding components to the VR Camera needed for fading view and getting controller poses.
       m_VrCamera.gameObject.AddComponent<OculusCameraFade>();
       m_VrCamera.gameObject.AddComponent<OculusPreCullHook>();
+
+      gameObject.AddComponent<OculusMRCCameraUpdate>();
 #endif // OCULUS_SUPPORTED
     } else if (App.Config.m_SdkMode == SdkMode.SteamVR) {
       // ---------------------------------------------------------------------------------------- //