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Add snippets for XR alpha04 hands #530

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Merged
merged 2 commits into from
May 22, 2025
Merged

Add snippets for XR alpha04 hands #530

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fa2bce8
Add snippet that demonstrates how to detect a secondary hand
devbridie May 7, 2025
58677d5
Add snippet to demonstrate how to detect a basic stop gesture
devbridie May 7, 2025
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37 changes: 37 additions & 0 deletions xr/src/main/java/com/example/xr/arcore/Hands.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@

package com.example.xr.arcore

import android.app.Activity
import androidx.activity.ComponentActivity
import androidx.lifecycle.lifecycleScope
import androidx.xr.arcore.Hand
Expand All @@ -28,8 +29,10 @@ import androidx.xr.runtime.SessionConfigureSuccess
import androidx.xr.runtime.math.Pose
import androidx.xr.runtime.math.Quaternion
import androidx.xr.runtime.math.Vector3
import androidx.xr.runtime.math.toRadians
import androidx.xr.scenecore.GltfModelEntity
import androidx.xr.scenecore.scene
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.launch

@Suppress("RestrictedApi") // b/416288516 - session.config and session.configure() are incorrectly restricted
Expand Down Expand Up @@ -65,6 +68,16 @@ fun ComponentActivity.collectHands(session: Session) {
}
}

fun secondaryHandDetection(activity: Activity, session: Session) {
fun detectGesture(handState: Flow<Hand.State>) {}
// [START androidxr_arcore_hand_handedness]
val handedness = Hand.getHandedness(activity.contentResolver)
val secondaryHand = if (handedness == Hand.Handedness.LEFT) Hand.right(session) else Hand.left(session)
val handState = secondaryHand?.state ?: return
detectGesture(handState)
// [END androidxr_arcore_hand_handedness]
}

fun ComponentActivity.renderPlanetAtHandPalm(leftHandState: Hand.State) {
val session: Session = null!!
val palmEntity: GltfModelEntity = null!!
Expand Down Expand Up @@ -106,3 +119,27 @@ fun ComponentActivity.renderPlanetAtFingerTip(rightHandState: Hand.State) {
indexFingerEntity.setPose(Pose(position, rotation))
// [END androidxr_arcore_hand_entityAtIndexFingerTip]
}

private fun detectPinch(session: Session, handState: Hand.State): Boolean {
// [START androidxr_arcore_hand_pinch_gesture]
val thumbTip = handState.handJoints[HandJointType.THUMB_TIP] ?: return false
val thumbTipPose = session.scene.perceptionSpace.transformPoseTo(thumbTip, session.scene.activitySpace)
val indexTip = handState.handJoints[HandJointType.INDEX_TIP] ?: return false
val indexTipPose = session.scene.perceptionSpace.transformPoseTo(indexTip, session.scene.activitySpace)
return Vector3.distance(thumbTipPose.translation, indexTipPose.translation) < 0.05
// [END androidxr_arcore_hand_pinch_gesture]
}

private fun detectStop(session: Session, handState: Hand.State): Boolean {
// [START androidxr_arcore_hand_stop_gesture]
val threshold = toRadians(angleInDegrees = 30f)
fun pointingInSameDirection(joint1: HandJointType, joint2: HandJointType): Boolean {
val forward1 = handState.handJoints[joint1]?.forward ?: return false
val forward2 = handState.handJoints[joint2]?.forward ?: return false
return Vector3.angleBetween(forward1, forward2) < threshold
}
return pointingInSameDirection(HandJointType.INDEX_PROXIMAL, HandJointType.INDEX_TIP) &&
pointingInSameDirection(HandJointType.MIDDLE_PROXIMAL, HandJointType.MIDDLE_TIP) &&
pointingInSameDirection(HandJointType.RING_PROXIMAL, HandJointType.RING_TIP)
// [END androidxr_arcore_hand_stop_gesture]
}