Camera looking direction vector

[Flyon]

After moving the camera around, I want to calculate the coordinates of
a point right in front of the camera, at say distance 100..
Is there any way to get the vector of my 'looking direction' ?

[Rich Elmes]

maybe there is something that i didn't find in away3d, but i achieved
this with this method :

create a dummy object (ObjectContainer3D)
copy position and rotation values from the camera to the dummy object
call moveForward(100) on the dummy object
now the dummy object is your point in front of the camera at distance
100 and difference in position between camera & dummy object is a
vector of your "looking direction"

[David Lenaerts]

There's an easier way if you directly use the camera's transformation matrix. The 3rd column of a transformation matrix is always the local Z-axis in the transformation's destination space. So the camera's transform object has its local z-axis (which is the "forward" vector) in scene coordinates. Getting that is pretty straightforward:

var camDirVector : Number3D = new Number3D(camera.transform.sxz, camera.transform.syz, camera.transform.szz);

Since your camera isn't (or shouldn't be) scaled, it's also unit-length, so a position 100 in front of the cam is simply as follows:

pos.x = cam.x + camDirVector.x*100;

pos.y = cam.y + camDirVector.y*100;

pos.z = cam.z + camDirVector.z*100;

Alternatively, you can also do something like this:

pos = new Number3D();

tgt = new Number3D(0, 0, 100);

pos.transform(tgt, camera.transform);

This literally means: I want an object 100 in front of the cam, but expressed in the camera's parent (ie: scene) coordinates. Both do the same thing, but the former method should be a bit faster, if it matters.

Hope that helps!

David

--
David Lenaerts
Flash platform developer
http://www.derschmale.com

[John Brookes]

Which brings me to the question isn't forward wrong in MatrixAway3D class?

As in, you should be able to do
pos.x = camera.position.x + camera.transform.forward.x*10;
pos.y = camera.position.y + camera.transform.forward.y*10;
pos.z = camera.position.z + camera.transform.forward.z*10;

but that doesn't work.

Change MatrixAway3D forward to

public function get forward():Number3D
{
    _forward.x = sxz //szx;
    _forward.y = syz  //szy;
    _forward.z = szz;
    return _forward;
}

Above works.

[Flyon]

Excelent!

The first solution worked perfect for me, and the second made me
better understand the transform function :)

tnx!