Ray->Sphere intersection?

Hi Devils Child,
I've written a function to reflect a ray below. To use it you need to perform the following steps:-

1 - Create a Unit Vector called Ray from Line start x,y,z to sphere intersection point ix,iy,iz:-

    global Ray.vector=new vector
    Ray\x=ix-x : Ray\y=iy-y : Ray\z=iz-z
    UnitVector(Ray)

2 - Create a Normal Unit Vector from the sphere center sx,sy,sz to the intersection point ix,iy,iz:-

   global Normal.vector=new vector
   Normal\x=ix-sx : Normal\y=iy-sy : Normal\z=iz-sz
   UnitVector(Normal)

3 - Now you can present these to the function ReflectRay to get the new ray direction:-

  newRay.vector=ReflectRay(Normal,Ray)

Hope that helps!

Cheers,

Roy

Type vector
    Field x#,y#,z#
End Type

Function ReflectRay.vector(normal.vector,ray.vector)
	Local newray.vector=New vector
	Local normpiv%=CreatePivot()
	AlignToVector normpiv,normal\x,normal\y,normal\z,3
	TFormVector ray\x,ray\y,ray\z,0,normpiv
	ray\x=TFormedX()
	ray\y=TFormedY()
	ray\z=TFormedZ()
	TurnEntity normpiv,0,0,180
	TFormVector ray\x,ray\y,ray\z,normpiv,0
	newray\x=-TFormedX()
	newray\y=-TFormedY()
	newray\z=-TFormedZ()
	FreeEntity normpiv
	UnitVector(newray)
	Return newray
End Function

Function UnitVector(v.vector)
	Local l#
	l=Sqr(v\x*v\x+v\y*v\y+v\z*v\z)
	If l=0 Then l=1
	v\x=v\x/l
	v\y=v\y/l
	v\z=v\z/l
	If Abs(v\x)<0.000001 Then v\x=0
	If Abs(v\y)<0.000001 Then v\y=0
	If Abs(v\z)<0.000001 Then v\z=0
End Function