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 localMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(origin);
            let inverseMatrix = Cesium.Matrix4.inverse(localMatrix, new Cesium.Matrix4);

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

            polygonPrimitive.modelMatrix = Cesium.Matrix4.multiply(localMatrix, modelMatrix, new Cesium.Matrix4);