feat(anchor): add createAnchor method on XRHitTestResult

Summary: The createAnchor method is not present in the HitTest module https://immersive-web.github.io/hit-test/#xr-hit-test-result-interface, but is tucked away in Anchors Module https://immersive-web.github.io/anchors/#dom-xrhittestresult-createanchor. This diff implements the createAnchor method on XRHitTestResult

Reviewed By: snagy

Differential Revision:
D44428490

Privacy Context Container: L1164747

fbshipit-source-id: f1894a89bdf6790e469819272c99ff01686ee4d9

polyfill/XRScene.js

@@ -188,7 +188,7 @@ export default class XRScene {
 		this.raycaster = new Raycaster();
 		this.hitTestTarget = new Object3D();
 		this.hitTestMarker = new Object3D();
-		this.hitTestMarker.rotateX(Math.PI / 2);
+		this.hitTestMarker.rotateX(-Math.PI / 2);
 		this.hitTestTarget.add(this.hitTestMarker);
 	}
 

polyfill/api/XRHitTestResult.js

@@ -1,20 +1,36 @@
 export const PRIVATE = Symbol('@@webxr-polyfill/XRHitTestResult');
+
+import { XRAnchor } from './XRAnchor';
+import { PRIVATE as XRFRAME_PRIVATE } from 'webxr-polyfill/src/api/XRFrame';
 import XRSpace from 'webxr-polyfill/src/api/XRSpace';
-import {
-  mat4
-} from 'gl-matrix';
+import { mat4 } from 'gl-matrix';
 
 export default class XRHitTestResult {
-  constructor(frame, transform) {
-    this[PRIVATE] = {
-      frame,
-      transform
-    };
-  }
+	constructor(frame, transform) {
+		this[PRIVATE] = {
+			frame,
+			transform,
+		};
+	}
+
+	getPose(baseSpace) {
+		const space = new XRSpace();
+		space._baseMatrix = mat4.copy(
+			mat4.create(),
+			this[PRIVATE].transform.matrix,
+		);
+		return this[PRIVATE].frame.getPose(space, baseSpace);
+	}
 
-  getPose(baseSpace) {
-    const space = new XRSpace();
-    space._baseMatrix = mat4.copy(mat4.create(), this[PRIVATE].transform.matrix);
-    return this[PRIVATE].frame.getPose(space, baseSpace);
-  }
+	async createAnchor() {
+		const anchorSpace = new XRSpace();
+		anchorSpace._baseMatrix = mat4.copy(
+			mat4.create(),
+			this[PRIVATE].transform.matrix,
+		);
+		const session = this[PRIVATE].frame[XRFRAME_PRIVATE].session;
+		const anchor = new XRAnchor(session, anchorSpace);
+		session.addTrackedAnchor(anchor);
+		return anchor;
+	}
 }