KML Lines not clamped to ground

[fironalia]

i have a kml that i want to add it to cesium, this kml contains lines and polygones.
polygones clamped to ground works fine, but lines are not working, is there any way to do it? or it is really a problem ??

[Crocsx]

Might be related to #4326

[fironalia]

this problem is related to kmldatasrouces.Only lines are not clamped.

[OmarShehata]

@fironalia please share a Sandcastle example reproducing this issue. If you're not sure if it's a bug you can always ask on the Cesium forum.

[fironalia]

@OmarShehata i am sure it is a bug, points and polygones are clamped to ground, but lines are not.
if you load any kml file that contains lines you will see that these lines are not clamped.
Polygones and points works fine.
i am loading points and polygones the same way with the lines.so for sure it is a bug, or there is something else missing that i dont know it.

[OmarShehata]

@fironalia submitting a complete bug report requires putting together a reproducible code example that shows the issue so we can test/debug it. Otherwise it's unclear whether the problem is in your code, or if it is a bug, where the issue may be.

For example, are you setting the clampToGround option when loading the KML as shown in the docs? https://cesium.com/docs/cesiumjs-ref-doc/KmlDataSource.html?classFilter=kmlData#.load

Here's a code example that shows that shows a line from a KML file clamped to ground in CesiumJS.

[fironalia]

i really thank you for your fast replies.
in the example, you are assigning to the coordinates an Altitude value (2357), i am not assigning an Altitude value to line coordinates same for the polygones. polygones without any altitude value, Clamped to ground works. but with lines it does not work.
And YES i am setting clampedToGround option when loading the KML.

[fironalia]

@OmarShehata this is an example for a kml file that conains one line and one polygon, if you want to try it. you will see that lines are clamped to ellipsoid and not to the terrain.
and the javascript code is :
var kml = kmlDataSrouce.load('http://examplehost/example.kml',
{
camera : viewer.scene.camera,
canvas: viewer.scene.canvas,
clampToGround : true
});
viewer.dataSources.add(kml);

example1.txt

[fironalia]

@OmarShehata am i right or wrong ?

[OmarShehata]

@fironalia your line is not clamped because the tesselate flag is false by default. You can fix this by adding <tessellate>1</tessellate>. I'm closing this because it's not a bug. I opened a PR inhttps://github.com//pull/8428 to add a warning when the clampToGround flag is ignored or perhaps to document the cases when a line cannot be clamped.

[fironalia]

@OmarShehata
when i add
**<tessellate>1</tessellate>** a message shows : An error occurred while rendering.Rendering has stopped.
i added tessellate to the same example i have sent right after the altitudeMode.

[fironalia]

@OmarShehata
i tried the file "example1" with <tessellate>1</tessellate> in googleEarth and no error occured.
but in cesium the same message shows "An error occurred while rendering.Rendering has stopped.Undefined Object"

If I dont write <tessellate>1</tessellate> no error occured but line not clamping, when i write <tessellate>1</tessellate> the error occurs.