Calculate near/far plane vertices using THREE.Frustum

Question

I need some help to deal with THREE.Frustum object. My problem: I need to calculate near/far plane vertices; I've taken a look at these tutorials - http://www.lighthouse3d.com/tutorials/view-frustum-culling/view-frustums-shape/ - http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-extracting-the-planes/ and I've sketched this function implementing exactly (I hope so) the procedure explained (just to get top-left/right vertices, assuming the camera can only look left and right): ``` // Near Plane dimensions hNear = 2 * Math.tan(camera.fov / 2) * camera.near; // height wNear = hNear * camera.aspect; // width // Far Plane dimensions hFar = 2 * Math.tan(camera.fov / 2) * camera.far; // height wFar = hFar * camera.aspect; // width getVertices : function() { var p = camera.position.clone(); var l = getCurrentTarget(); // see below var u = new THREE.Vector3(0, 1, 0); var d = new THREE.Vector3(); d.sub(l, p); d.normalize(); var r = new THREE.Vector3(); r.cross(u, d);…

Accepted Answer

`Three.Frustum` is not really going to help you -- it is a set of planes. The good news is your solution appears correct, but there is an easier way to think about this.

The upper right corner of the near plane is a point in camera space with these coordinates:

```
var ntr = new THREE.Vector3( wNear / 2, hNear / 2, -camera.near );
```

using your definition of `wNear` and `hNear`, which are correct.

Now, making sure that `camera.matrixWorld` is updated, you convert that point to world coordinates like so:

```
camera.updateMatrixWorld();
ntr.applyMatrix4( camera.matrixWorld );
```

Now, flip the signs to get the other three corners, and then repeat the calculation for the far plane.

See, you had it right; you just took a more complicated route. :-)

EDIT: updated to three.js r.66

Calculate near/far plane vertices using THREE.Frustum

Solution

Problem

Related problems