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;