[Papervision3D] Z-fighting/clipping issue with plotting objects on a globe (sphere)

[Paul Tondeur]

Hi Aaron,

The sorting on your globe can perfectly solved with viewportLayers.  
The globe can be rendered at layer 1 and the planes at layer 2, so  
they will appear always on top.

An example implementation of this looks as follows:

var globe:Sphere = new Sphere();
scene.addChild(sphere);

var plane:Plane = new Plane();
scene.addChild(plane);

var globeLayer:ViewportLayer = viewport.getChildLayer(globe);
var planeLayer:ViewportLayer = viewport.getChildLayer(plane);
globeLayer.layerIndex = 1;
planeLayer.layerIndex = 2;
viewport.containerSprite.sortMode = ViewportLayerSortMode.INDEX_SORT;

This is just one of the ways you can use viewport layers. I hope this  
helps.

Paul

On Jul 3, 2009, at 12:18 AM, Aaron Meyers wrote:

> Hello,
>
> I am starting work on a project where objects will be plotted on the  
> earth. I've put together a quick test and found that when i position  
> objects around a sphere, I have some clipping problems with the  
> polygons of these objects. I put together an example to show what  
> I'm talking about:
>
> http://aaron-meyers.com/globetest/
>
> You can click to change from plotting planes to cubes. I've actually  
> offset the planes a bit away from the radius of the sphere, but the  
> clipping problem is still pretty severe. I once encountered  
> something similar in an OpenGL project and it turned out to be z- 
> fighting and after adjusting the near clip and far clip distance on  
> my projection matrix, it was fine. I suspect something like this  
> might be the cause of my problem, but I don't really understand the  
> inner workings of the Papervision3D transformation pipeline.
>
> Does anyone know how to get around this? Any tips? Thanks for any  
> help.
>
> -Aaron
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