Ray.intersectsSphere(sphere) is incorrect for empty Spheres

[jmeurice]

Description

The intersectsSphere(sphere) of Ray is not correct for empty Spheres:

intersectsSphere( sphere ) {
    return this.distanceSqToPoint( sphere.center ) <= ( sphere.radius * sphere.radius );
}

Spheres use radius=-1 to indicate "empty", which is not correctly considered when squaring it here.

This breaks raycasting when testing objects with empty geometries (in some conditions, like when the ray passes close to the origin/Sphere's center)

Reproduction steps

1. Raycast an empty object (with uninitialized BufferGeometry), for example Line

Code

scene = new THREE.Scene();
scene.add(new THREE.Line()) // Empty geometry in Line
    
const raycaster = new THREE.Raycaster() // Default ray traverses the origin -> distance to empty Sphere-center will be 0 < (-1*-1)
raycaster.intersectObject(scene) // Throws an error (intersectsSphere() doesn't exclude properly)

Live example

• jsfiddle

Screenshots

No response

Version

r176

Device

No response

Browser

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OS

No response

[jmeurice]

A simple fix would be:

intersectsSphere( sphere ) {
    if (sphere.radius < 0) return false;
    return this.distanceSqToPoint( sphere.center ) <= ( sphere.radius * sphere.radius );
}

[Mugen87]

I wonder if the default value of radius could be 0 again. That was actually the original value but it was changed via #19000.

[mrdoob]

What do you think @WestLangley?

I think we should be able to support scenes that have empty geometries (for whatever reason).

[WestLangley]

TBH, the simple fix proposed above by the OP seems fine to me.

[Mugen87]

@jmeurice Do you mind creating a PR with your suggested change?

[Mugen87]

In the meanwhile I have filed a PR so we can get this in for r177.