Clarify the need to call scene.render in between picks with pickTranslucentDepth in docs

[bkuster]

I'm trying to pick the position of a translucent primitive as outlined in #4511, which was closed with #4979.

What I expected: setting the scene.pickTranslucentDepth to true will allow me to not pick through translucent primitives, but this is not the case. Am I missunderstanding the docs?

Set Scene#pickTranslucentDepth to true to include the depth of translucent primitives

To recreate use this sandcastle and add this at line 5:

viewer.scene.pickTranslucentDepth = true;
viewer.screenSpaceEventHandler.setInputAction(function onLeftClick(movement) {
    var pickedFeature = viewer.scene.pick(movement.position);
    if (!Cesium.defined(pickedFeature)) {
        console.log("nothing");
        return;
    }

    console.log(viewer.scene.pickPosition(movement.position));
}, Cesium.ScreenSpaceEventType.LEFT_CLICK);

Clicking on the translucent wall Primitive or one of the rectangles in the Atlantic when facing the horizon will not pick the position of the Primitive but log undefined.

[hpinkos]

Hi @bkuster. You need to call scene.render between picks. This fixed the example for me:'

viewer.screenSpaceEventHandler.setInputAction(function onLeftClick(movement) {
    var pickedFeature = viewer.scene.pick(movement.position);
    if (!Cesium.defined(pickedFeature)) {
        console.log("nothing");
        return;
    }
    viewer.scene.render();
    console.log(viewer.scene.pickPosition(movement.position));
}, Cesium.ScreenSpaceEventType.LEFT_CLICK);

In the future, please ask questions like this on the forum: https://groups.google.com/forum/?hl=en#!forum/cesium-dev
We use GitHub exclusively for tracking bugs and planning new features. Thanks!

[ggetz]

@hpinkos Reopened to make this clear in the reference docs.

See https://groups.google.com/forum/#!topic/cesium-dev/C-yXSf6-8aQ

[cesium-concierge]

Congratulations on closing the issue! I found these Cesium forum links in the comments above:

https://groups.google.com/forum/#!topic/cesium-dev/C-yXSf6-8aQ

If this issue affects any of these threads, please post a comment like the following:

The issue at #6151 has just been closed and may resolve your issue. Look for the change in the next stable release of Cesium or get it now in the master branch on GitHub https://github.com/AnalyticalGraphicsInc/cesium.

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