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XR Plugin reports wrong eye positions #86

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Shii2 opened this issue Mar 22, 2021 · 2 comments · May be fixed by #105
Open

XR Plugin reports wrong eye positions #86

Shii2 opened this issue Mar 22, 2021 · 2 comments · May be fixed by #105

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@Shii2
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Shii2 commented Mar 22, 2021

Left and Right eye position Y an Z coordinates always equals to Center eye Y and Z coordinates.
Here is a video demonstrating the problem: https://www.youtube.com/watch?v=9Bp0c7_XvuY
Reproduced problem in both Unity 2019.4.22f1 and Unity 2020.3.0f1, using SteamVR 1.16.10, OpenVR Unity XR plugin v1.1.4 and Oculus Rift CV1 headset.
This is the only bug preventing us from migrating our project from Legacy VR and Unity 2019.4.22f1 to XR Plugin and Unity 2020.3
Here is the code that used in above video to report eye positions:

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.XR;

public class EyePosTest : MonoBehaviour
{
	public Text leftEyePosValue;
	public Text rightEyePosValue;
	public Text centerEyePosValue;
	public Text headPosValue;

	void Update()
	{
		Vector3 leftEyePosition;
		Vector3 rightEyePosition;
		Vector3 centerEyePosition;
		Vector3 headPosition;
		TryGetEyeFeature(out leftEyePosition, XRNode.LeftEye);
		TryGetEyeFeature(out rightEyePosition, XRNode.RightEye);
		TryGetEyeFeature(out centerEyePosition, XRNode.CenterEye);
		TryGetEyeFeature(out headPosition, XRNode.Head);
		leftEyePosValue.text = leftEyePosition.ToString("F4");
		rightEyePosValue.text = rightEyePosition.ToString("F4");
		centerEyePosValue.text = centerEyePosition.ToString("F4");
		headPosValue.text = headPosition.ToString("F4");
	}

	private bool TryGetEyeFeature(out Vector3 position, XRNode eye)
	{
		InputFeatureUsage<Vector3> inputFeatureUsage = CommonUsages.devicePosition;
		if (eye == XRNode.LeftEye)
			inputFeatureUsage = CommonUsages.leftEyePosition;
		else if (eye == XRNode.RightEye)
			inputFeatureUsage = CommonUsages.rightEyePosition;
		else if (eye == XRNode.CenterEye)
			inputFeatureUsage = CommonUsages.centerEyePosition;
		else if (eye == XRNode.Head)
			inputFeatureUsage = CommonUsages.devicePosition;

		InputDevice device = InputDevices.GetDeviceAtXRNode(XRNode.Head);
		if (device.isValid)
		{
			if (device.TryGetFeatureValue(inputFeatureUsage, out position))
				return true;
		}
		// This is the fail case
		position = Vector3.zero;
		return false;
	}
}
@leekentvr
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leekentvr commented Mar 22, 2021 •
edited
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image

Another visualisation of the bug, with headset looking straight on, and looking to the right. The left eye (green) and right eye (red) are also flipped over.
The do not rotate around the centre point as would be expected.

@Shii2
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Shii2 commented Sep 29, 2021 •
edited
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Analyzed unity-xr-plugin source code and found a fix!
Issue was found in file

unity-xr-plugin/Providers/Input/Input.cpp

Line 477 in 739417c

xrTrackingTransformRef *= reinterpret_cast< XRMatrix4x4 & >( *postTransform );
at line 477 and this happens because wrong matrix multiplication order is used.
To fix the issue replace this line with:
xrTrackingTransformRef = reinterpret_cast< XRMatrix4x4 & >( *postTransform ) * xrTrackingTransformRef;

@Shii2 Shii2 mentioned this issue Sep 29, 2021
Open
Shii2 added a commit to Shii2/unity-xr-plugin that referenced this issue Sep 29, 2021
@Shii2
Fix for wrong Y and Z coordinates of left and right eye
7c8b925 
Fixes ValveSoftware#86
@Shii2 Shii2 linked a pull request Sep 29, 2021 that will close this issue
Open
zite added a commit that referenced this issue Mar 23, 2023
@zite
Removed preinit, fixed eye position, fixed depth texture, sdk to 1.23.7
4f95aae 
- Updated to SteamVR SDK 1.23.7
- Fix for unnecessary preinit #80
- Fix for incorrect reporting of eye position #86
- Fix for broken depth textures in some situations #110
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Fix for wrong Y and Z coordinates of left and right eye Shii2/unity-xr-plugin
2 participants
@leekentvr @Shii2