The geometric energy added by the Primitive can not change the property？

CesiumJS
1

1. A concise explanation of the problem you're experiencing.

The geometric energy added by the Primitive can not change the property?

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

  viewer.scene.primitives.add(new Cesium.Primitive({
          geometryInstances: new Cesium.GeometryInstance({
                geometry: new Cesium.PolygonGeometry({
                polygonHierarchy : new Cesium.PolygonHierarchy(
                  Cesium.Cartesian3.fromDegreesArray([
                    -72.0, 40.0,
                    -70.0, 35.0,
                    -75.0, 30.0,
                    -70.0, 30.0,
                    -68.0, 40.0
                  ])
                ),
                 extrudedHeight: 300000
              })
          }),
          appearance: new Cesium.EllipsoidSurfaceAppearance({
            aboveGround: false,
            material: WaterMaterial
          }),
          show: true
     }))

As shown in the code, I add a PolygonGeometry,But I can't dynamically change the value of extrudedHeight，

I tried to dynamically change the value of extrudedHeight with the Cesium.CallbackProperty() method，But it doesn't work。

I hope the teacher can help me solve the problem,Thanks!
                                                        
                                                           Liu from China.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

I want to change the extrudedHeight property dynamically.Primitive must be used.Because of the use of material.

4. The Cesium version you're using, your operating system and browser.

2

Hi Liu,

Here is an example of how to use Cesium.CallbackProperty.

You would do the following:

    extrudedHeight : new Cesium.CallbackProperty(function(time, result) {

        // Get the value for extruded height

        return extrudedHeight;

    }, false)

is “geometric energy” a custom property? If so, you can access the value like this:

 var propertyValues = entity.properties.getValue(viewer.clock.currentTime);

 propertyValues.custom_property;

Thanks,

Gabby

3

Hi Gabby,

I changed my code：

var extrudedHeightCallback = 5000;

scene.primitives.add(new Cesium.Primitive({

geometryInstances: new Cesium.GeometryInstance({

geometry: new Cesium.PolygonGeometry({

polygonHierarchy : new Cesium.PolygonHierarchy(

Cesium.Cartesian3.fromDegreesArray([

-72.0, 40.0,

-70.0, 35.0,

-75.0, 30.0,

-70.0, 30.0,

-68.0, 40.0

])

),

extrudedHeight: new Cesium.CallbackProperty(function(time, result) {

// Get the value for extruded height

console.log(result);

return extrudedHeightCallback += 50;

}, false)

})

}),

appearance: new Cesium.EllipsoidSurfaceAppearance({

aboveGround: false,

material: WaterMaterial

}),

show: true

}))

This does not work，I think it might be that I used Primitive, not Entity,The use of CallbackProperty in Entity is successful,But Primitive can’t do it？

Thanks,

Liu

4

My mistake, I didn’t see that you were using a Primitive. What we do under the hood for entities is create a new primitive when a relevant value is updated, and destroy the old primitive.

var newExtrudedHeight = extrudedHeight + 50;

primitives.remove(oldPrimitive);

oldPrimitive.destroy();

// create the new primitive with the newExtrudedHeight

You’ll want to put the above block in an function that updates with the simulation time, see Clock.onTick.

Thanks,

Gabby