How to say ahead of the cam by this much?

General Discussion
1

Hi!

I need some help understanding how to ie. create something in front of wherever the camera (cam.) is  looking (not relevant of it's up vector) …

I have cam.getDirection()

and cam.getLocation()

I'm guessing we'd somehow mix those with some maths and some value H which is a float expressing how far ahead of the cam do we want to go. But since I'm no good at Maths and a newbie at jME(jme2 btw), I was hoping someone could help me get this idea :slight_smile:

Thank you in advance people!

Cheers!



PS: or point me to the relevant documentation

2


Vector3f targetTranslation = cam.getLocation().add(cam.getDirection().mult(NunitsAwayFromCam));



set targetTranslation as the localtranslation of the object you want there.
3

Cool! That is so awesome! Thank you mucho  :smiley:

That is very intuitive.



I am reading that localTranslation is "Spatial's translation relative to its parent. " so I am deducing that both the camera and my new object are children of ie. rootNode (aka parent) and that is why localTranslation "works"… and obviously they are both Spatial :slight_smile: I find myself thinking if this works for any Spatials in any location in the tree, but I am guessing it should work… so for example:

root->Z->X->W->K->cam

root->A->B->C

where leftmost are parents and to the right are children of parents…

and if I wanted to move C in front of cam, I would still use localTranslation right? like:

float NunitsAwayFromCam=10f;
Vector3f targetTranslation = cam.getLocation().add(cam.getDirection().mult(NunitsAwayFromCam));
C.setLocalTranslation( targetTranslation );


This would work even if cam and C don't have same common parent? (well they do have root as indirect common parent) but I wonder if when doing ie. ".mult()" above , does the localTranslation get transformed into worldTranslation of sorts? else it wouldn't make sense, unless I'm missing something (as per usual)  XD
4
abugsfriend said:

where leftmost are parents and to the right are children of parents...
and if I wanted to move C in front of cam, I would still use localTranslation right? like:


hi there, no that won't work unless the parent nodes dont have a localTranslation for their own. But you can search the forum for "setWorldTranslation" which lets you find out the the appropriat localTranslation to set so it fits.