Cesium從入門放棄8：模型編輯Demo[轉]

就是這個東西

 

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.畫坐標軸

2.1 定義箭頭線

坐標軸看上去是個帶箭頭的線，但是Cesium並沒有定義箭頭線的幾何對象，Entity倒是可以給一個箭頭材質，但是模型旋轉平移涉及復雜的矩陣變換，所以Entity並不是一個好的選擇，用Entity也許你能很方便的畫出坐標軸，但是矩陣變換估計能把你整暈了，因此我們寧願畫坐標軸的時候多花點心思。下面是我基本Primitive封裝的一個箭頭線，實現的原理是一個圓柱加一個圓錐。

export default class ArrowPolyline {
/**
* 箭頭線
*/
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
//這里用的是圓錐幾何對象，當topRadius和bottomRadius相同時，它就是一個圓柱
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 })
})
});
}
/**
* 按上面的方法畫出的箭頭在線的中間，我們需要把它平移到線的一端
*/
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 以模型中心為原點創建坐標軸

model.readyPromise.then(m => {
const center1 = Cesium.Matrix4.getTranslation(
m.modelMatrix,
new Cesium.Cartesian3()
);
//必須在模型加載完成后才能讀到boundingSphere屬性
const boundingShpere = m.boundingSphere;
const radius = boundingShpere.radius
const axisZ = new GV.ArrowPolyline({
id: "axisZ",
color: Cesium.Color.RED,
position: center1,
width: 3,
headWidth: 5,
length: radius * 2 + 50,//坐標軸的長度應該視模型的直徑而定
headLength: 10
});
const axisX = new GV.ArrowPolyline({
id: "axisX",
color: Cesium.Color.GREEN,
position: center1,
width: 3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisY = new GV.ArrowPolyline({
id: "axisY",
color: Cesium.Color.BLUE,
position: center1,
width: 3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
viewer.scene.primitives.add(axisZ)
viewer.scene.primitives.add(axisX)
viewer.scene.primitives.add(axisY)
});

三個坐標軸已經創建完了，但是如果你打開瀏覽器應該只看到一條軸，應該它們是重疊在一起的，並且方向朝上，也就是說我們畫了三條Z軸，以右手坐標系為例，Z軸繞Y軸逆時針旋轉90度到到X軸，Z軸繞X軸旋轉逆時針旋轉90度得到Y軸。因此對X、Y軸做矩陣變換 。

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,
width: 3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisX = new GV.ArrowPolyline({
id: "axisX",
color: Cesium.Color.GREEN,
position: center1,
width: 3,
headWidth: 5,
length: radius * 2 + 50,
headLength: 10
});
const axisY = new GV.ArrowPolyline({
id: "axisY",
color: Cesium.Color.BLUE,
position: center1,
width: 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.創建圍繞坐標軸的圓

這里肯定有很多方法，我的實現思路以模型中心為圓心，模型半徑為半徑畫圓。

3.1 定義創建坐標圓的方法

function createAxisSphere(id, position, matrix, color) {
const geometry = new Cesium.PolylineGeometry({
positions: position,
width: 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 計算圓周坐標

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 創建坐標軸圓弧

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.結語

至此，最前面展示的內容就已經完成了，剩下的就是交互了,前面已經寫過了，具體請參考
Cesium從入門放棄7：模型矩陣變換

原文鏈接 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，實現完畢，感謝共享