Cesium从入门放弃8：模型编辑Demo[转]

就是这个东西

1.添加模型

const url = "Apps/model/leida.glb";
const pos = Cesium.Cartesian3.fromDegrees(110, 40, 150);
const matrix = Cesium.Transforms.eastNorthUpToFixedFrame(pos);
const model = viewer.scene.primitive.add(
   Cesium.Model.fromGltf({
　　url: url,
　　modelMatrix: matrix
　　})
　);
});
viewer.camera.lookAtTransform(matrix, new Cesium.Cartesian3(-50, 0, 800));

2.画坐标轴

2.1 定义箭头线

坐标轴看上去是个带箭头的线，但是Cesium并没有定义箭头线的几何对象，Entity倒是可以给一个箭头材质，但是模型旋转平移涉及复杂的矩阵变换，所以Entity并不是一个好的选择，用Entity也许你能很方便的画出坐标轴，但是矩阵变换估计能把你整晕了，因此我们宁愿画坐标轴的时候多花点心思。下面是我基本Primitive封装的一个箭头线，实现的原理是一个圆柱加一个圆锥。

export default class ArrowPolyline {
/**
* 箭头线
*/
constructor(option = {}) {
this._color = option.color || Cesium.Color.RED;
this._width = option.width || 3;
this._headWidth = option.headWidth || 2 * this._width;
this._length = option.length || 300
this._headLength = option.headLength || 10
this._inverse = option.inverse || false
this.position = option.position
const id = option.id
//这里用的是圆锥几何对象，当topRadius和bottomRadius相同时，它就是一个圆柱
const line = Cesium.CylinderGeometry.createGeometry(new Cesium.CylinderGeometry({
length: this._length,
topRadius: this._width,
bottomRadius: this._width
}));
const arrow = Cesium.CylinderGeometry.createGeometry(new Cesium.CylinderGeometry({
length: this._headLength,
topRadius: 0,
bottomRadius: this._headWidth
}));
let offset = (this._length + this._headLength) / 2
if (this._inverse) {
offset = -offset
}

ArrowPolyline.translate(arrow, [0, 0, offset]);

return new Cesium.Primitive({
modelMatrix: Cesium.Transforms.eastNorthUpToFixedFrame(this.position),
geometryInstances: [new Cesium.GeometryInstance(
{
id: id + '-line',
geometry: line,
}
),
new Cesium.GeometryInstance({
id: id + '-arrow',
geometry: arrow,
})],
appearance: new Cesium.MaterialAppearance({
material: Cesium.Material.fromType('Color', { color: this._color })
})
});
}
/**
* 按上面的方法画出的箭头在线的中间，我们需要把它平移到线的一端
*/
static translate = function (geometry, offset) {
const scratchOffset = new Cesium.Cartesian3();
if (Cesium.isArray(offset)) {
scratchOffset.x = offset[0];
scratchOffset.y = offset[1];
scratchOffset.z = offset[2];
} else {
Cesium.Cartesian3.clone(offset, scratchOffset);
}

for (let i = 0; i < geometry.attributes.position.values.length; i += 3) {
geometry.attributes.position.values[i] += scratchOffset.x;
geometry.attributes.position.values[i + 1] += scratchOffset.y;
geometry.attributes.position.values[i + 2] += scratchOffset.z;
}
}
}

2.2 以模型中心为原点创建坐标轴

model.readyPromise.then(m => {
const center1 = Cesium.Matrix4.getTranslation(
m.modelMatrix,
new Cesium.Cartesian3()
);
//必须在模型加载完成后才能读到boundingSphere属性
const boundingShpere = m.boundingSphere;
const radius = boundingShpere.radius
const axisZ = new GV.ArrowPolyline({
id: "axisZ",
color: Cesium.Color.RED,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,//坐标轴的长度应该视模型的直径而定
headLength: 10
});
const axisX = new GV.ArrowPolyline({
id: "axisX",
color: Cesium.Color.GREEN,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisY = new GV.ArrowPolyline({
id: "axisY",
color: Cesium.Color.BLUE,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
viewer.scene.primitives.add(axisZ)
viewer.scene.primitives.add(axisX)
viewer.scene.primitives.add(axisY)
});

三个坐标轴已经创建完了，但是如果你打开浏览器应该只看到一条轴，应该它们是重叠在一起的，并且方向朝上，也就是说我们画了三条Z轴，以右手坐标系为例，Z轴绕Y轴逆时针旋转90度到到X轴，Z轴绕X轴旋转逆时针旋转90度得到Y轴。因此对X、Y轴做矩阵变换 。

model.readyPromise.then(m => {
const center1 = Cesium.Matrix4.getTranslation(
m.modelMatrix,
new Cesium.Cartesian3()
);
const boundingShpere = m.boundingSphere;
const radius = boundingShpere.radius
const axisZ = new GV.ArrowPolyline({
id: "axisZ",
color: Cesium.Color.RED,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisX = new GV.ArrowPolyline({
id: "axisX",
color: Cesium.Color.GREEN,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisY = new GV.ArrowPolyline({
id: "axisY",
color: Cesium.Color.BLUE,
position: center1,
3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});

const mx = Cesium.Matrix3.fromRotationY(Cesium.Math.toRadians(90));
const rotationX = Cesium.Matrix4.fromRotationTranslation(mx);
Cesium.Matrix4.multiply(
axisX.geometryInstances[0].modelMatrix,
rotationX,
axisX.geometryInstances[0].modelMatrix
);
Cesium.Matrix4.multiply(
axisX.geometryInstances[1].modelMatrix,
rotationX,
axisX.geometryInstances[1].modelMatrix
);
const my = Cesium.Matrix3.fromRotationX(Cesium.Math.toRadians(90));
const rotationY = Cesium.Matrix4.fromRotationTranslation(my);
Cesium.Matrix4.multiply(
axisY.geometryInstances[0].modelMatrix,
rotationY,
axisY.geometryInstances[0].modelMatrix
);
Cesium.Matrix4.multiply(
axisY.geometryInstances[1].modelMatrix,
rotationY,
axisY.geometryInstances[1].modelMatrix
);
viewer.scene.primitives.add(axisZ)
viewer.scene.primitives.add(axisX)
viewer.scene.primitives.add(axisY)
});

3.创建围绕坐标轴的圆

这里肯定有很多方法，我的实现思路以模型中心为圆心，模型半径为半径画圆。

3.1 定义创建坐标圆的方法

function createAxisSphere(id, position, matrix, color) {
const geometry = new Cesium.PolylineGeometry({
positions: position,
10
});
const instnce = new Cesium.GeometryInstance({
geometry: geometry,
id: id,
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(color)
}
});
return new Cesium.Primitive({
geometryInstances: instnce,
appearance: new Cesium.PolylineColorAppearance({
translucent: false
}),
modelMatrix: matrix
});
}

3.2 计算圆周坐标

const position = [];
for (let i = 0; i <= 360; i += 3) {
const sin = Math.sin(Cesium.Math.toRadians(i));
const cos = Math.cos(Cesium.Math.toRadians(i));
const x = radius * cos;
const y = radius * sin;
position.push(new Cartesian3(x, y, 0));
}

3.3 创建坐标轴圆弧

const axisSphereZ = self.createAxisSphere(
"axisSphereZ",
position,
matrix,
Cesium.Color.RED
);
viewer.scene.primitives.add(axisSphereZ);
const axisSphereY = self.createAxisSphere(
"axisSphereY",
position,
matrix,
Cesium.Color.GREEN
);
viewer.scene.primitives.add(axisSphereY);
Cesium.Matrix4.multiply(
axisSphereY.geometryInstances.modelMatrix,
rotationY,
axisSphereY.geometryInstances.modelMatrix
);
const axisSphereX = self.createAxisSphere(
"axisSphereX",
position,
matrix,
Cesium.Color.BLUE
);
viewer.scene.primitives.add(axisSphereX);
Cesium.Matrix4.multiply(
axisSphereX.geometryInstances.modelMatrix,
rotationX,
axisSphereX.geometryInstances.modelMatrix
);

4.结语

至此，最前面展示的内容就已经完成了，剩下的就是交互了,前面已经写过了，具体请参考
Cesium从入门放弃7：模型矩阵变换

原文链接 https://blog.csdn.net/xtfge0915/article/details/105277427/?utm_medium=distribute.pc_relevant.none-task-blog-title-2&spm=1001.2101.3001.4242

 有用，实现完毕，感谢共享