rest/example/fox-ar/components/tap-to-place.js

AFRAME.registerComponent('tap-to-place', {
    init() {
        this.raycaster = new THREE.Raycaster()
        this.camera = document.getElementById('camera')
        this.threeCamera = this.camera.getObject3D('camera')
        this.ground = document.getElementById('ground')
        document.querySelector('#tap-to-place-cursor').setAttribute('visible', 'true')
        // 2D coordinates of the raycast origin, in normalized device coordinates (NDC)---X and Y
        // components should be between -1 and 1.  Here we want the cursor in the center of the screen.
        this.rayOrigin = new THREE.Vector2(0, 0)
        this.cursorLocation = new THREE.Vector3(0, 0, 0)
        this.onTap = this.onTap.bind(this)
        this.el.sceneEl.addEventListener('touchstart', this.onTap)
    },
    remove() {
        this.el.sceneEl.removeEventListener('touchstart', this.onTap)
    },
    tick() {
        this.raycaster.setFromCamera(this.rayOrigin, this.threeCamera)
        const intersects = this.raycaster.intersectObject(this.ground.object3D, true)
        if (intersects.length > 0) {
            const [intersect] = intersects
            this.cursorLocation = intersect.point
        }
        this.el.object3D.position.y = 0.1
        this.el.object3D.position.lerp(this.cursorLocation, 0.4)
        this.el.object3D.lookAt(this.threeCamera.position.x, this.el.object3D.position.y, this.threeCamera.position.z)
    },
    onTap() {
        document.querySelector('#tap-to-place-cursor').setAttribute('visible', 'false')
        this.el.emit('placed')
        this.el.removeAttribute('tap-to-place')
    },
})