public boolean collides(Sphere s) {
float a = mDirection.dot(mDirection);
float b = 2 * mDirection.dot(mOrigin);
float c = mOrigin.dot(mOrigin) - (s.radius * s.radius);
float disc = b * b - 4 * a * c;
if (disc < 0) return false;
float distSqrt = (float) Math.sqrt(disc);
float q;
if (b < 0) q = (-b - distSqrt) / 2.0f;
else q = (-b + distSqrt) / 2.0f;
// compute t0 and t1
float t0 = q / a;
float t1 = c / q;
// make sure t0 is smaller than t1
if (t0 > t1) {
// if t0 is bigger than t1 swap them around
float temp = t0;
t0 = t1;
t1 = temp;
}
// if t1 is less than zero, the object is in the ray's negative direction
// and consequently the ray misses the sphere
return t1 >= 0;
}
public void RayFromPoints(Vector3 v0, Vector3 v1) {
mOrigin = v0;
mDirection = v1.clone().sub(v0);
mDirection.normalize();
}