Function xQuickCullForRay

src/SB/Core/x/xCollide.cpp:2666–2668

    xVec3 d1 = v2 - v1;
    xVec3 d2 = v1 - center;

    F32 r = radius + width;
    F32 f31 = d1.length2();
    F32 b = 2.0f * d1.dot(d2);
    F32 q = SQR(b) - 4.0f * f31 * (d2.length2() - SQR(r));