Cesium快速上手2-Model图元使用讲解

Model示例讲解链接地址，注意是开发模式的示例
http://localhost:8080/Apps/Sandcastle/index.html?src=development%2F3D%20Models.html&label=Development

image.png

minimumPixelSize : 128 //保证不管地球缩放到多小，这个飞机依然能看得见

 model = scene.primitives.add(Cesium.Model.fromGltf({
        url : url,
        modelMatrix : modelMatrix,
        minimumPixelSize : 128 //保证不管地球缩放到多小，这个飞机依然能看得见
    }));

createModel具体使用讲解

modelMatrix
Cesium.Transforms.headingPitchRollToFixedFrame
Model readyPromise
camera.lookAt

//origin 基于空间直角坐标系，已地球的圆心为原点建的坐标系，本初子午线为X轴；origin = 需要从经纬度转为空间直角坐标系的值
//hpr 相对于飞机自身的三个旋转角度，heading左右摇头的角度，改变航向；Pitch 上下抬头低头角度，上正下负；Roll相对于视线方向，从左到右旋转的角度；
//在地球上的不同位置，飞机的初始姿态是不一样的。需要根据不同的位置初始化飞机的位置
//异步创建，
// camera.lookAt 调整相机角度，才能看到飞机的位置；设置视觉中心点，视觉角度；鼠标坐标拖动时可以看到，是围绕着视觉中心点进行旋转的，若需要解绑的话，需要用另外一个函数
//camera.lookAt Transform(Cesium.Matrix4.IDENTITY)可以完成解绑。

function createModel(url, height, heading, pitch, roll) {
    height = Cesium.defaultValue(height, 0.0);
    heading = Cesium.defaultValue(heading, 0.0);
    pitch = Cesium.defaultValue(pitch, 0.0);
    roll = Cesium.defaultValue(roll, 0.0);
    var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);

    var origin = Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706, height);
    var modelMatrix = Cesium.Transforms.headingPitchRollToFixedFrame(origin, hpr);

    scene.primitives.removeAll(); // Remove previous model
    model = scene.primitives.add(Cesium.Model.fromGltf({
        url : url,
        modelMatrix : modelMatrix,
        minimumPixelSize : 128
    }));

    model.readyPromise.then(function(model) {
        model.color = Cesium.Color.fromAlpha(getColor(viewModel.color), Number(viewModel.alpha));
        model.colorBlendMode = getColorBlendMode(viewModel.colorBlendMode);
        model.colorBlendAmount = viewModel.colorBlendAmount;
        // Play and loop all animations at half-speed
        model.activeAnimations.addAll({
            multiplier : 0.5,
            loop : Cesium.ModelAnimationLoop.REPEAT
        });

        var camera = viewer.camera;

        // Zoom to model
        var controller = scene.screenSpaceCameraController;
        var r = 2.0 * Math.max(model.boundingSphere.radius, camera.frustum.near);
        controller.minimumZoomDistance = r * 0.5;

        var center = Cesium.Matrix4.multiplyByPoint(model.modelMatrix, model.boundingSphere.center, new Cesium.Cartesian3());
        var heading = Cesium.Math.toRadians(230.0);
        var pitch = Cesium.Math.toRadians(-20.0);
        camera.lookAt(center, new Cesium.HeadingPitchRange(heading, pitch, r * 2.0));
    }).otherwise(function(error){
        window.alert(error);
    });
}

注册事件 ScreenSpaceEventHandler

scene.pick
scene.pick之后需要判断的属性字段根据你的需求而定，这里我们关注的是model，所以判断model的属性是否存在。
scene.pick之后判断model的属性是否存在

var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
handler.setInputAction(function(movement) {
    var pick = scene.pick(movement.endPosition);
    if (Cesium.defined(pick) && Cesium.defined(pick.node) && Cesium.defined(pick.mesh)) {
        // Output glTF node and mesh under the mouse.
        console.log('node: ' + pick.node.name + '. mesh: ' + pick.mesh.name);
    }
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

Sandcastle使用讲解

cesium 是通过knockout.js完成页面DOM和数据绑定操作的.关键语句如下：
toolbar
Cesium.knockout
Cesium.knockout.track(viewModel)
Cesium.knockout.applyBindings(viewModel, toolbar)

// 在html中
<table><tbody>
    <tr>
        <td>Mode</td>
        <td><select data-bind="options: colorBlendModes, value: colorBlendMode"></select></td>
    </tr>

// 在js中
// The viewModel tracks the state of our mini application.
var viewModel = {
    color : 'White',
    colors : ['White', 'Red', 'Green', 'Blue', 'Yellow', 'Gray'],
    alpha : 1.0,
    colorBlendMode : 'Highlight',
    colorBlendModes : ['Highlight', 'Replace', 'Mix'],
    colorBlendAmount : 0.5,
    colorBlendAmountEnabled : false
};

// Convert the viewModel members into knockout observables.
Cesium.knockout.track(viewModel);

// Bind the viewModel to the DOM elements of the UI that call for it.
var toolbar = document.getElementById('toolbar');
Cesium.knockout.applyBindings(viewModel, toolbar);


Cesium.knockout.getObservable(viewModel, 'colorBlendMode').subscribe(
    function(newValue) {
        var colorBlendMode = getColorBlendMode(newValue);
        model.colorBlendMode = colorBlendMode;
        viewModel.colorBlendAmountEnabled = (colorBlendMode === Cesium.ColorBlendMode.MIX);
    }
);

mode下的terrainProvider 属性

image.png

terrainProvider 其实是属于global的，这里是做了个快捷方式，直接访问了global.terrainProvider ;
还有很多类似这样的属性都是快捷方式。

ModelInstance示例讲解

scene 要创建1024个飞机，考虑渲染性能，一次把1024个飞机一次绘制出来，降低绘制批次，优化渲染性能。
ModelInstance 在文档里面没有，是因为ModelInstance.js文档里面有@private关键字，所以自动生成文档的时候没有该关键字。
链接地址
http://localhost:8080/Apps/Sandcastle/index.html?src=development%2F3D%20Models%20Instancing.html&label=Development

image.png

 var collection = scene.primitives.add(new Cesium.ModelInstanceCollection({
        url : url,
        instances : instances
    }));

Model子节点控制

http://localhost:8080/Apps/Sandcastle/index.html?src=development%2F3D%20Models%20Node%20Explorer.html&label=Development

image.png

改动子节点关键代码，获取子节点的名字model.getNode，改动node.matrix

 // respond to viewmodel changes by applying the computed matrix
    Cesium.knockout.getObservable(viewModel, 'matrix').subscribe(function(newValue) {
        var node = model.getNode(viewModel.nodeName);
        if (!Cesium.defined(node.originalMatrix)) {
            node.originalMatrix = node.matrix.clone();
        }
        node.matrix = Cesium.Matrix4.multiply(node.originalMatrix, newValue, new Cesium.Matrix4());
    });

本文转自 https://www.jianshu.com/p/ca1fe4735b38，如有侵权，请联系删除。