pickPosition picks groundPrimitive BoundingVolume on pickTranslucentDepth

[jbo023]

Hi,

we have some problems with pickTranslucentDepth and GroundPrimitives. If we call pickPosition and set pickTranslucentDepth to true, pickPosition will pick the BoundingVolume of the GroundPrimitive.

In the Sandcastle, you can reproduce this by left clicking on the polygon and the area around. The logged height should return a value around 100m, but if the boundingvolume of the polygon is hit, the height will get up to 1200m.

Maybe in a pickTranslucent Pickpass the boundingvolume can be skipped ?

Sandcastle example:

var viewer = new Cesium.Viewer('cesiumContainer', {
    terrainProvider: Cesium.createWorldTerrain(),
    selectionIndicator : false,
    infoBox : false
});
var handler;
var scene = viewer.scene;
Sandcastle.addToolbarButton('Pick position', function() {     
    var bluePolygon = viewer.entities.add({
        name : 'Bluepolygon',
        polygon : {
            hierarchy : {
                positions : Cesium.Cartesian3.fromDegreesArrayHeights([13.508413568947175, 52.624609203388985,63.489969498150046,
                                                                13.507974260302085,52.62343609585099,62.40131342659079,
                                                                13.512261239882516,52.623435464323194,62.62432512380137,
                                                                13.512411447299176,52.62507247479826,64.79929751403317])
            },
            material : Cesium.Color.BLUE
        }
    });
    viewer.scene.camera.flyTo({
        destination:Cesium.Cartesian3.fromRadians(0.23573022033928406,  0.9180339714130956,2468.1889113351654),
        orientation: {
            direction: new Cesium.Cartesian3(-0.9763134662556562,-0.2010860623885384,-0.07985243340649456),
            up: new Cesium.Cartesian3(-0.08359955704461564,0.010197801592665909,0.996447248430453)
        },
        duration: 0
    });
    handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
    handler.setInputAction(function(movement) {
        var scene = viewer.scene;        
        var pickedObject = scene.pick(movement.position);
        if(pickedObject) {
         pickedObject.primitive.debugShowBoundingVolume = true;   
        }
        if (scene.pickPositionSupported) {
            scene.pickTranslucentDepth = true;
            viewer.scene.render();            
            var cartesian = viewer.scene.pickPosition(movement.position);
            scene.pickTranslucentDepth = false;

            if (Cesium.defined(cartesian)) {
                var cartographic = Cesium.Cartographic.fromCartesian(cartesian);
                console.log(cartographic.height);
            }            
        }
    }, Cesium.ScreenSpaceEventType.RIGHT_CLICK);
});


Sandcastle.reset = function() {
    viewer.entities.removeAll();
    handler = handler && handler.destroy();
};

[jbo023]

I think, i found a possible solution for this problem.

if picking and renderTranslucentDepthForPick are true, we don't need to render classification passes.
At least I think it is not necessary, because the result for position picks don't change if we left out the classification passes. As they should not change the geometry.

For the above sandcastle, the following change fixes the problem, but i am not sure if there are other implications.
virtualcitySYSTEMS@2c92954

[jbo023]

Do you have any thoughts no this problem, should i open a merge request

[hpinkos]

Whoops, sorry we missed this issue @jbo023. @lilleyse @bagnell thoughts on this?

[lilleyse]

@jbo023 that fix works. You should go ahead and open a PR.

Though we should also look at the underlying issue. Because of the required render call before pickPosition the commands that are used in the renderTranslucentDepth pass don't have pickOnly set and depth commands are rendered instead. If we can, we should try to remove the requirement of calling render before pickPosition. I might have an idea for that.

[lilleyse]

@jbo023 I incorporated your fix into https://github.com/CesiumGS/cesium/tree/globe-alpha 32e2953