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Bug in scene.pick ?


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I'm currently using a lot of picking actions, as described in this playground : http://www.babylonjs.com/playground/#1HCGBN


This scene is a simple ground in a biiiiig red sphere (a skydome).

A click on the ground creates a box. Try to click on the sphere in front of you : no box.

Well, there is a box... Press the 'back' arrow key of your keyboard. Surprise !


What ?The box is behind me ? What the hell ... ?


I came to the conclusion there was a bug in the function scene.pick, so I tried to investigate...

And here is what I found : 

Ray.prototype.intersectsTriangle = function (vertex0, vertex1, vertex2) {    ...    var det = Vector3.Dot(this._edge1, this._pvec);    if (det === 0) {        return null;    }    ...}

In my case, the box is behind the camera because the dot product is negative. I think (but I'm not sure as I'm not a math professional :/ ) that it should never be negative in a picking case...

So I added this : 

if (det <= 0 ) {    return null;}

And it works... But I don't have any box on my ground now :/ 


Help me Babylon lovers ! What should I do ?



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Yes, but the sphere cannot be targeted anymore :/


Actually I want to pick always in front of the camera, not behind it. How can something like this be achieved ? In my mind, it can be if the cos between my two vectors is > 0, thus the dot product > 0... But I don't understand why it does not work with the ground :(

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