app/node_modules/@babylonjs/core/XR/features/WebXRWalkingLocomotion.js

import { TmpVectors, Vector2, Vector3 } from "../../Maths/math.vector.js";
import { Logger } from "../../Misc/logger.js";
import { Observable } from "../../Misc/observable.js";
import { WebXRFeatureName, WebXRFeaturesManager } from "../webXRFeaturesManager.js";
import { WebXRAbstractFeature } from "./WebXRAbstractFeature.js";
class CircleBuffer {
    constructor(numSamples, initializer) {
        this._samples = [];
        this._idx = 0;
        for (let idx = 0; idx < numSamples; ++idx) {
            this._samples.push(initializer ? initializer() : Vector2.Zero());
        }
    }
    get length() {
        return this._samples.length;
    }
    push(x, y) {
        this._idx = (this._idx + this._samples.length - 1) % this._samples.length;
        this.at(0).copyFromFloats(x, y);
    }
    at(idx) {
        if (idx >= this._samples.length) {
            throw new Error("Index out of bounds");
        }
        return this._samples[(this._idx + idx) % this._samples.length];
    }
}
class FirstStepDetector {
    constructor() {
        this._samples = new CircleBuffer(20);
        this._entropy = 0;
        this.onFirstStepDetected = new Observable();
    }
    update(posX, posY, forwardX, forwardY) {
        this._samples.push(posX, posY);
        const origin = this._samples.at(0);
        this._entropy *= this._entropyDecayFactor;
        this._entropy += Vector2.Distance(origin, this._samples.at(1));
        if (this._entropy > this._entropyThreshold) {
            return;
        }
        let samePointIdx;
        for (samePointIdx = this._samePointCheckStartIdx; samePointIdx < this._samples.length; ++samePointIdx) {
            if (Vector2.DistanceSquared(origin, this._samples.at(samePointIdx)) < this._samePointSquaredDistanceThreshold) {
                break;
            }
        }
        if (samePointIdx === this._samples.length) {
            return;
        }
        let apexDistSquared = -1;
        let apexIdx = 0;
        for (let distSquared, idx = 1; idx < samePointIdx; ++idx) {
            distSquared = Vector2.DistanceSquared(origin, this._samples.at(idx));
            if (distSquared > apexDistSquared) {
                apexIdx = idx;
                apexDistSquared = distSquared;
            }
        }
        if (apexDistSquared < this._apexSquaredDistanceThreshold) {
            return;
        }
        const apex = this._samples.at(apexIdx);
        const axis = apex.subtract(origin);
        axis.normalize();
        const vec = TmpVectors.Vector2[0];
        let dot;
        let sample;
        let sumSquaredProjectionDistances = 0;
        for (let idx = 1; idx < samePointIdx; ++idx) {
            sample = this._samples.at(idx);
            sample.subtractToRef(origin, vec);
            dot = Vector2.Dot(axis, vec);
            sumSquaredProjectionDistances += vec.lengthSquared() - dot * dot;
        }
        if (sumSquaredProjectionDistances > samePointIdx * this._squaredProjectionDistanceThreshold) {
            return;
        }
        const forwardVec = TmpVectors.Vector3[0];
        forwardVec.set(forwardX, forwardY, 0);
        const axisVec = TmpVectors.Vector3[1];
        axisVec.set(axis.x, axis.y, 0);
        const isApexLeft = Vector3.Cross(forwardVec, axisVec).z > 0;
        const leftApex = origin.clone();
        const rightApex = origin.clone();
        apex.subtractToRef(origin, axis);
        if (isApexLeft) {
            axis.scaleAndAddToRef(this._axisToApexShrinkFactor, leftApex);
            axis.scaleAndAddToRef(this._axisToApexExtendFactor, rightApex);
        }
        else {
            axis.scaleAndAddToRef(this._axisToApexExtendFactor, leftApex);
            axis.scaleAndAddToRef(this._axisToApexShrinkFactor, rightApex);
        }
        this.onFirstStepDetected.notifyObservers({
            leftApex: leftApex,
            rightApex: rightApex,
            currentPosition: origin,
            currentStepDirection: isApexLeft ? "right" : "left",
        });
    }
    reset() {
        for (let idx = 0; idx < this._samples.length; ++idx) {
            this._samples.at(idx).copyFromFloats(0, 0);
        }
    }
    get _samePointCheckStartIdx() {
        return Math.floor(this._samples.length / 3);
    }
    get _samePointSquaredDistanceThreshold() {
        return 0.03 * 0.03;
    }
    get _apexSquaredDistanceThreshold() {
        return 0.09 * 0.09;
    }
    get _squaredProjectionDistanceThreshold() {
        return 0.03 * 0.03;
    }
    get _axisToApexShrinkFactor() {
        return 0.8;
    }
    get _axisToApexExtendFactor() {
        return -1.6;
    }
    get _entropyDecayFactor() {
        return 0.93;
    }
    get _entropyThreshold() {
        return 0.4;
    }
}
class WalkingTracker {
    constructor(leftApex, rightApex, currentPosition, currentStepDirection) {
        this._leftApex = new Vector2();
        this._rightApex = new Vector2();
        this._currentPosition = new Vector2();
        this._axis = new Vector2();
        this._axisLength = -1;
        this._forward = new Vector2();
        this._steppingLeft = false;
        this._t = -1;
        this._maxT = -1;
        this._maxTPosition = new Vector2();
        this._vitality = 0;
        this.onMovement = new Observable();
        this.onFootfall = new Observable();
        this._reset(leftApex, rightApex, currentPosition, currentStepDirection === "left");
    }
    _reset(leftApex, rightApex, currentPosition, steppingLeft) {
        this._leftApex.copyFrom(leftApex);
        this._rightApex.copyFrom(rightApex);
        this._steppingLeft = steppingLeft;
        if (this._steppingLeft) {
            this._leftApex.subtractToRef(this._rightApex, this._axis);
            this._forward.copyFromFloats(-this._axis.y, this._axis.x);
        }
        else {
            this._rightApex.subtractToRef(this._leftApex, this._axis);
            this._forward.copyFromFloats(this._axis.y, -this._axis.x);
        }
        this._axisLength = this._axis.length();
        this._forward.scaleInPlace(1 / this._axisLength);
        this._updateTAndVitality(currentPosition.x, currentPosition.y);
        this._maxT = this._t;
        this._maxTPosition.copyFrom(currentPosition);
        this._vitality = 1;
    }
    _updateTAndVitality(x, y) {
        this._currentPosition.copyFromFloats(x, y);
        if (this._steppingLeft) {
            this._currentPosition.subtractInPlace(this._rightApex);
        }
        else {
            this._currentPosition.subtractInPlace(this._leftApex);
        }
        const priorT = this._t;
        const dot = Vector2.Dot(this._currentPosition, this._axis);
        this._t = dot / (this._axisLength * this._axisLength);
        const projDistSquared = this._currentPosition.lengthSquared() - (dot / this._axisLength) * (dot / this._axisLength);
        // TODO: Extricate the magic.
        this._vitality *= 0.92 - 100 * Math.max(projDistSquared - 0.0016, 0) + Math.max(this._t - priorT, 0);
    }
    update(x, y) {
        if (this._vitality < this._vitalityThreshold) {
            return false;
        }
        const priorT = this._t;
        this._updateTAndVitality(x, y);
        if (this._t > this._maxT) {
            this._maxT = this._t;
            this._maxTPosition.copyFromFloats(x, y);
        }
        if (this._vitality < this._vitalityThreshold) {
            return false;
        }
        if (this._t > priorT) {
            this.onMovement.notifyObservers({ deltaT: this._t - priorT });
            if (priorT < 0.5 && this._t >= 0.5) {
                this.onFootfall.notifyObservers({ foot: this._steppingLeft ? "left" : "right" });
            }
        }
        if (this._t < 0.95 * this._maxT) {
            this._currentPosition.copyFromFloats(x, y);
            if (this._steppingLeft) {
                this._leftApex.copyFrom(this._maxTPosition);
            }
            else {
                this._rightApex.copyFrom(this._maxTPosition);
            }
            this._reset(this._leftApex, this._rightApex, this._currentPosition, !this._steppingLeft);
        }
        if (this._axisLength < 0.03) {
            return false;
        }
        return true;
    }
    get _vitalityThreshold() {
        return 0.1;
    }
    get forward() {
        return this._forward;
    }
}
class Walker {
    static get _MillisecondsPerUpdate() {
        // 15 FPS
        return 1000 / 15;
    }
    constructor(engine) {
        this._detector = new FirstStepDetector();
        this._walker = null;
        this._movement = new Vector2();
        this._millisecondsSinceLastUpdate = Walker._MillisecondsPerUpdate;
        this.movementThisFrame = Vector3.Zero();
        this._engine = engine;
        this._detector.onFirstStepDetected.add((event) => {
            if (!this._walker) {
                this._walker = new WalkingTracker(event.leftApex, event.rightApex, event.currentPosition, event.currentStepDirection);
                this._walker.onFootfall.add(() => {
                    Logger.Log("Footfall!");
                });
                this._walker.onMovement.add((event) => {
                    this._walker.forward.scaleAndAddToRef(0.024 * event.deltaT, this._movement);
                });
            }
        });
    }
    update(position, forward) {
        forward.y = 0;
        forward.normalize();
        // Enforce reduced framerate
        this._millisecondsSinceLastUpdate += this._engine.getDeltaTime();
        if (this._millisecondsSinceLastUpdate >= Walker._MillisecondsPerUpdate) {
            this._millisecondsSinceLastUpdate -= Walker._MillisecondsPerUpdate;
            this._detector.update(position.x, position.z, forward.x, forward.z);
            if (this._walker) {
                const updated = this._walker.update(position.x, position.z);
                if (!updated) {
                    this._walker = null;
                }
            }
            this._movement.scaleInPlace(0.85);
        }
        this.movementThisFrame.set(this._movement.x, 0, this._movement.y);
    }
}
/**
 * A module that will enable VR locomotion by detecting when the user walks in place.
 */
export class WebXRWalkingLocomotion extends WebXRAbstractFeature {
    /**
     * The module's name.
     */
    static get Name() {
        return WebXRFeatureName.WALKING_LOCOMOTION;
    }
    /**
     * The (Babylon) version of this module.
     * This is an integer representing the implementation version.
     * This number has no external basis.
     */
    static get Version() {
        return 1;
    }
    /**
     * The target to be articulated by walking locomotion.
     * When the walking locomotion feature detects walking in place, this element's
     * X and Z coordinates will be modified to reflect locomotion. This target should
     * be either the XR space's origin (i.e., the parent node of the WebXRCamera) or
     * the WebXRCamera itself. Note that the WebXRCamera path will modify the position
     * of the WebXRCamera directly and is thus discouraged.
     */
    get locomotionTarget() {
        return this._locomotionTarget;
    }
    /**
     * The target to be articulated by walking locomotion.
     * When the walking locomotion feature detects walking in place, this element's
     * X and Z coordinates will be modified to reflect locomotion. This target should
     * be either the XR space's origin (i.e., the parent node of the WebXRCamera) or
     * the WebXRCamera itself. Note that the WebXRCamera path will modify the position
     * of the WebXRCamera directly and is thus discouraged.
     */
    set locomotionTarget(locomotionTarget) {
        this._locomotionTarget = locomotionTarget;
        this._isLocomotionTargetWebXRCamera = this._locomotionTarget.getClassName() === "WebXRCamera";
    }
    /**
     * Construct a new Walking Locomotion feature.
     * @param sessionManager manager for the current XR session
     * @param options creation options, prominently including the vector target for locomotion
     */
    constructor(sessionManager, options) {
        super(sessionManager);
        this._up = new Vector3();
        this._forward = new Vector3();
        this._position = new Vector3();
        this._movement = new Vector3();
        this._sessionManager = sessionManager;
        this.locomotionTarget = options.locomotionTarget;
        if (this._isLocomotionTargetWebXRCamera) {
            Logger.Warn("Using walking locomotion directly on a WebXRCamera may have unintended interactions with other XR techniques. Using an XR space parent is highly recommended");
        }
    }
    /**
     * Checks whether this feature is compatible with the current WebXR session.
     * Walking locomotion is only compatible with "immersive-vr" sessions.
     * @returns true if compatible, false otherwise
     */
    isCompatible() {
        return this._sessionManager.sessionMode === undefined || this._sessionManager.sessionMode === "immersive-vr";
    }
    /**
     * Attaches the feature.
     * Typically called automatically by the features manager.
     * @returns true if attach succeeded, false otherwise
     */
    attach() {
        if (!this.isCompatible || !super.attach()) {
            return false;
        }
        this._walker = new Walker(this._sessionManager.scene.getEngine());
        return true;
    }
    /**
     * Detaches the feature.
     * Typically called automatically by the features manager.
     * @returns true if detach succeeded, false otherwise
     */
    detach() {
        if (!super.detach()) {
            return false;
        }
        this._walker = null;
        return true;
    }
    _onXRFrame(frame) {
        const pose = frame.getViewerPose(this._sessionManager.baseReferenceSpace);
        if (!pose) {
            return;
        }
        const handednessScalar = this.locomotionTarget.getScene().useRightHandedSystem ? 1 : -1;
        const m = pose.transform.matrix;
        this._up.copyFromFloats(m[4], m[5], handednessScalar * m[6]);
        this._forward.copyFromFloats(m[8], m[9], handednessScalar * m[10]);
        this._position.copyFromFloats(m[12], m[13], handednessScalar * m[14]);
        // Compute the nape position
        this._forward.scaleAndAddToRef(0.05, this._position);
        this._up.scaleAndAddToRef(-0.05, this._position);
        this._walker.update(this._position, this._forward);
        this._movement.copyFrom(this._walker.movementThisFrame);
        if (!this._isLocomotionTargetWebXRCamera) {
            Vector3.TransformNormalToRef(this._movement, this.locomotionTarget.getWorldMatrix(), this._movement);
        }
        this.locomotionTarget.position.addInPlace(this._movement);
    }
}
//register the plugin
WebXRFeaturesManager.AddWebXRFeature(WebXRWalkingLocomotion.Name, (xrSessionManager, options) => {
    return () => new WebXRWalkingLocomotion(xrSessionManager, options);
}, WebXRWalkingLocomotion.Version, false);
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