cesium primitive 移动 缩放 旋转 矩阵

旋转参考：cesium 指定点旋转rectangle Primitive方式 矩阵篇-CSDN博客

平移参考：cesium 调整3dtiles的位置 世界坐标下 相对坐标下 平移矩阵-CSDN博客

一、primitive方式添加polygon

let polygonInstance = new Cesium.GeometryInstance({

geometry: Cesium.PolygonGeometry.fromPositions({

positions: Cesium.Cartesian3.fromDegreesArray([

...p1,

p2[0], p1[1],

...p2,

p1[0], p2[1]

]),

height: 0,

vertexFormat: Cesium.EllipsoidSurfaceAppearance.VERTEX_FORMAT

}),

attributes: {

color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromCssColorString('#00ff00').withAlpha(0.5))

}

});

let polygonPrimitive = new Cesium.Primitive({

geometryInstances: [polygonInstance],

undisplayable: true,

appearance: new Cesium.PerInstanceColorAppearance({

flat: true,

translucent: false

})

});

viewer.scene.primitives.add(polygonPrimitive);

二、平移

以p1为原点，将p1移动到（113.392209, 38.095546），其他几个点相对p1移动

let origin = Cesium.Cartesian3.fromDegrees(...p1);

let offset = Cesium.Cartesian3.fromDegrees(

113.392209, 38.095546

);

let translate = Cesium.Cartesian3.subtract(

offset,

origin,

new Cesium.Cartesian3()

);

polygonPrimitive.modelMatrix = Cesium.Matrix4.fromTranslation(translate)

三、缩放

以p1为原点，在x轴方向缩放2倍大小

let origin = Cesium.Cartesian3.fromDegrees(...p1);

let localToWorld_Matrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);

let worldToLocal_Matrix = Cesium.Matrix4.inverse(localToWorld_Matrix, new Cesium.Matrix4);

let scaleMatrix = Cesium.Matrix4.fromScale(new Cesium.Cartesian3(2, 1, 1));

let localScaleMatrix = Cesium.Matrix4.multiply(scaleMatrix, worldToLocal_Matrix, new Cesium.Matrix4);

let worldMatrix = Cesium.Matrix4.multiply(localToWorld_Matrix, localScaleMatrix, new Cesium.Matrix4);

polygonPrimitive.modelMatrix = worldMatrix;

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