基于WebGL-ThingJS的的平面图导航（二）

前言

基于WebGL架构的3D可视化平台—平面图导航（一）中已经完成了iframe面板与我们的3D场景的简单交互，下面我们继续完善并给iframe页加上鼠标悬停事件让iframe页的img标签和我们场景中的obj一起动起来。

实现

第一步，还是使用之前的场景接着上次的继续，先编写iframe页。给每一个img标签都加上onmouseover、onmouseout 事件。

第二步，房间里的物体不要要让他“飞起来”，还要给他加一个“底座”。这里叫他SurveillanceCamera类，在自己编写类的时候一定要注意，想要当前类生效一定要继承THING.Thing，并且THING.factory.registerClass(‘ClassName’, ClassName);

class SurveillanceCamera extends THING.Thing {

constructor(app) {
    super(app);
    this.app = app;
    this.isFrustum = true;
    this.opacity = 1;
    this.color = 0xff00ff;
    this.vertices = [];
    this.near = 0.1;
    this.camera = null;
    this.node = new THREE.Object3D();
    this._frustum = new THREE.Frustum();
    this._projScreenMatrix = new THREE.Matrix4();

}

setup(param) {
    super.setup(param);
    this.fov = param['fov'];
    this.aspect = param['aspect'];
    this.far = param['far'];
    this.alpha = param['alpha'];
    this.lineAlpha = param['lineAlpha'];
    this.setupComplete(param);
}

setupComplete(param) {
    super.setupComplete(param);
    this.build();
}

build() {
    if (this.node.children.length > 0) {
        this.node.children = [];
    }

    if (this.camera != null) {
        this.camera = null;
    }

    var h = this.far * Math.tan(this.fov * 0.5 * 0.017453293);
    var w = this.aspect * h;

    var geometry = new THREE.Geometry();
    this.vertices = [new THREE.Vector3(0, 0, 0), new THREE.Vector3(w, -h, -this.far), new THREE.Vector3(w, h, -this.far), new THREE.Vector3(-w, h, -this.far), new THREE.Vector3(-w, -h, -this.far)];
    var faces = [new THREE.Face3(0, 1, 2), new THREE.Face3(0, 2, 3), new THREE.Face3(0, 3, 4), new THREE.Face3(0, 4, 1), new THREE.Face3(3, 4, 1), new THREE.Face3(3, 1, 2)];
    geometry.vertices = this.vertices;

    var line_mat = new THREE.LineBasicMaterial({
        color: "#b4f5f8",
        opacity: this.lineAlpha || 0.5,
    })

    var texture = THREE.ImageUtils.loadTexture("images/light2.png");
    texture.wrapS = THREE.RepeatWrapping;
    texture.wrapT = THREE.RepeatWrapping;
    var frustum_mat = new THREE.MeshBasicMaterial({
        color: "#0aa5ff",
        opacity: this.alpha || 0.5,
        transparent: true,
        side: THREE.DoubleSide,
    });
    var line_mesh = new THREE.Line(geometry, line_mat);

    var frustum_mesh = new THREE.Mesh(geometry, frustum_mat);
    geometry.faces = faces;
    this.node.add(frustum_mesh, line_mesh);

    this.camera = new THREE.PerspectiveCamera(this.fov, this.aspect, this.near, this.far);
    this.camera.position.set(this.position[0], this.position[1], this.position[2]);
    this.camera.rotation.copy(this.node.rotation);

    this.camera.updateMatrixWorld(true);
    this._updateFrustum();
}

setPosition() {
    this.camera.position.set(this.position[0], this.position[1], this.position[2]);
    this.camera.updateMatrixWorld(true);
    this._updateFrustum();
}

_updateFrustum() {
    if (this.camera) {
        this._projScreenMatrix.multiplyMatrices(this.camera.projectionMatrix, this.camera.matrixWorldInverse);
        this._frustum.setFromMatrix(this._projScreenMatrix);
    }
}

intersectsObject(object) {
    this._updateFrustum();
    return this._frustum.intersectsObject(object);
}

intersectsBox(box) {
    this._updateFrustum();
    return this._frustum.intersectsBox(box);
}

intersectsSphere(sphere) {
    this._updateFrustum();
    return this._frustum.intersectsSphere(sphere);
}

intersectsSprite(sprite) {
    this._updateFrustum();
    return this._frustum.intersectsSprite(sprite);
}

}

THING.factory.registerClass('SurveillanceCamera', SurveillanceCamera);

第三步，鼠标悬浮事件和鼠标离开事件，这里我们使用了之前创建的SurveillanceCamera类为obj加上了一个“底座”。

//鼠标悬浮事件
function onMouseOver(targetObj,viewPoint) {

if (currentModule != null)
    return;
overModule = app.query(targetObj)[0];
overModule.style.boundingBox = true;
overModule.moveTo({
    "offset": [0, 6, 0],
    "time": 80,
});
sCamera = app.create({
    type: 'SurveillanceCamera',
    name: 'SurveillanceCamera_',
    position:app.query(viewPoint)[0].position,
    fov: 65,
    aspect: 1.3,
    far: 6,
});
sCamera.angleX = 90;
sCamera.style.opacity = 0.1;

}
//鼠标离开事件
function onMouseOut(targetObj) {

if (currentModule != null)
    return;
if (sCamera) {
    sCamera.destroy();
    sCamera = null;
}
outModule = overModule;
outModule.style.boundingBox = false;
outModule.stopMoving();
outModule.position = [0, 0, 0];
outModule = null;

}

演示地址：EXAMPLE

总结

利用iframe与ThingJS进行交互完成了平面图导航功能，通过自制的HTML界面，嵌入ThingJS的面板中，形成一个可自定义的导航界面，通过偏移实现相应的视觉效果。

制作一个视锥，达到投放影像的效果，这里运用面向对象的方式是为了，能够更快捷的创建视锥，起到复用的作用。

在制作过程中，将物体悬浮的过程时出现了问题，发现如果快速的操作鼠标，物体不会达到预期的视觉效果，例如，鼠标快速的在两个导航图之间切换时，对应的两个物体会不断的上升，尽管将上升与还原的速度加快，也依然无法解决问题。最后解决的办法是：新添加一个变量，将上一次悬浮的物体记录下来，就是文中的 outModule，通过对 outModule 单独操作来解决影响问题。