Ahiru

Mesh facing the camera

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Maybe I am just a bit slow understanding, but how can I actually bring a mesh to face the camera? (And further more: Only do that turning around its local "Z"-Axe)

Here my trials so far:

http://playground.babylonjs.com/#12U7QB#2

Even tried to find out the angle between the actual rotation and the camera, but the actual rotation does not really look right?

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how can I actually bring a mesh to face the camera? 

 

I added a feature in Babylon 2.2 that is available since yesterday: getFrontPosition (distance) to place an object in front of the camera and whatever the rotation and position of the camera.

 

exemple:

sphere.position = camera.getFrontPosition(12); //Sphere has 12 unit front the camera.

This what you were asking?

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No - nice function, but probably not what I need at the moment.

 

You see the cylinder lying on the box, right? And I want it to turn its face always to the camera. (But without standing up - it still has to lie flat like it does now - only this movement like shown at the moment allowed)

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If you want to rotate a mesh into a known target system (ex : cube top sides and camera axis) so it always face the cam, you may use Vector3.RotationFromAxis() to get the needed rotation angles.

 

doc : http://doc.babylonjs.com/overviews/How_Rotations_and_Translations_Work  ("generating a rotation from a target system" part)

ex : http://www.babylonjs-playground.com/#VYM1E#5

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Well - it can't completely face you, because it's fixed on the "Ship" - maybe it's clearer now like this? http://playground.babylonjs.com/#12U7QB#5

 

So it can't completely face you (only when the box is aligned correctly), but it can at least turn in your direction on the axis it CAN move. I tried to find out the angle, so I can put it into the quaternion rotation, but I am still not sure how to find this angle. If the cannon would move like you suggested it will break the ship :D

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Yes, like this, but that was easy to solve, since click-point, ship and face-to point are all on the same plane. But could not work it out yet to make it work when they are not ...

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Hmm, I see... well, then I don't know either :P

Just an idea: maybe you can make them use the same (imaginary) plane for the calculation and then rotate according to that?

Trying to illustrate the idea: http://playground.babylonjs.com/#12U7QB#8

By the way: how do I get the coordinates of a mesh in world space?? I somehow couldn't figure it out... might be too late... or just my lack of knowledge... but please tell me :D

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plane.position = cylinder.getAbsolutePosition(); (Don't get confused by the console.log show 0,0,0 - if you expand it the real numbers are shown - no idea why that is)

 

But I am struggling with getting the "absolute" rotation of the cylinder. After I rotate it with the .rotate() function - which is done with quaternions - the rotation is always (0,0,0). So now I try to find out how to rotate with quaternions manually.

 

Because how much I have to turn depends not only on the cylinders position, but also on the rotation, right?

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