Get orientation of an Object3d child

Question

Ok, here is the problem: I am using a PerspectiveCamera as a child of an Object3d to chase it.

...
player.add(backCamera);
backCamera.position.set(0, 10, -80);
backCamera.lookAt(player.position);
...

Now i am trying to use a Raycaster to find the objects between the camera and the player and make them invisible, but i need the camera position and the camera orientation.

Thanks to this question i was able to find the "true" camera position like that:

...
player.updateMatrixWorld();
var vector = new THREE.Vector3();
var temp = vector.setFromMatrixPosition(backCamera.matrixWorld);
...

but i still need to find the "true" camera orientation. I tried to follow this approach and the approach linked in that question as well.

...
var pLocal = new THREE.Vector3( 0, 0, -1 );
var pWorld = pLocal.applyMatrix4(backCamera.matrixWorld);
var direction = pWorld.sub(backCamera.position).normalize();

raycaster.set(temp, direction);
...

but seems like the ray is not properly oriented, probably because the orientation is relative to the parent object.

Since the camera is a child of another object, you need to subtract off the camera's world position -- not `camera.position`. — WestLangley, May 21 '14 at 14:06
hmm @WestLangley why is there no .setFromMatrixRotation? I figured he could just use that, but it's missing... — Doidel, May 26 '14 at 07:32

score 1 · Accepted Answer · answered May 21 '14 at 13:25

1

Knowing the target position (say, TP, Target Position) that the camera is looking at, and you know the camera position (say, VRP, View Reference Point), the camera orientation is simply given by:

TP-VRP

That you may want to normalize as well.

answered May 21 '14 at 13:25

cifz

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Get orientation of an Object3d child

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