Cesium 中两种添加 model 方法的区别

概述

Cesium 中包含两种添加 model 的方法，分别为：

viewer.entities.add()viewer.scene.primitives.add()

方法 1方法 2

两种方法的区别

表面区别

方法 1方法 2方法 1方法 2方法 1方法 2

深层探究

方法 1方法 2方法 1方法 2

{

	id: object

	mesh: ModelMesh

	node: ModeNode

	primitive: Model

}

方法 2方法 1方法 1方法 2

从 Entity 获得 Model 的方法

function getModelForEntity(entity) {

    var primitives = viewer.scene.primitives;

    for (var i = 0; i < primitives.length; i++) {

        var primitive = primitives.get(i);

        if (primitive instanceof Cesium.Model && primitive.id === entity) {

            return primitive;

        }

    }

};

其它知识点

构建的对象中还包含 ModelMesh 和 ModeNode，ModelMesh 中包含了模型的网格和材质，ModeNode 中包含了一个 transform，可以在运行时对模型进行动态变换，以实现自定义模型动画。

示例代码

1. 方法1

function createModel(url, height) {

    viewer.entities.removeAll();
var position = Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706, height);

    var heading = Cesium.Math.toRadians(135);

    var pitch = 0;

    var roll = 0;

    var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);

    var orientation = Cesium.Transforms.headingPitchRollQuaternion(position, hpr);
var entity = viewer.entities.add({

        name : url,

        position : position,

        orientation : orientation,

        model : {

            uri : url,

            minimumPixelSize : 128,

            maximumScale : 20000

        }

    });

    viewer.trackedEntity = entity;

}

1. 方法2

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({

            speedup : 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);

    });

}