# [Bf-committers] ior

Ivan Sedo ikoframe at zoznam.sk
Sun Jun 12 17:14:29 CEST 2005

```Hi Ton,
have you checked possible issues with that yet?

Ivan

On Sun, 2005-04-03 at 15:52 +0200, Ton Roosendaal wrote:
> Hi,
>
> The camera is in 'void', so when it sends rays the first material hit
> will be an IOR > 1.0. For every subsequent hit the IOR value is 1/ior
> flipped.
>
> could be useful yah. Will check on the problems that come with that! :)
>
> -Ton-
>
> On 3 Apr, 2005, at 15:26, Frédéric van der Essen wrote:
>
> > Ooops...
> > replace "negative" by "<=1" and "positive" by ">=1" in my post and it
> > should be correct...
> > Physically, Ior ranges ]0,->[
> >
> >
> >> indeed it is not negative, if one ior was i_1 than for the opposite
> >> direction the ior is i_2 = 1/i_1
> >>
> >> it comes out from senll's law
> >>
> >>
> >> Anyway
> >> On Sun, 2005-04-03 at 12:56 +0200, Frédéric van der Essen wrote:
> >>
> >>> Of course it can !
> >>> the ior isn't lightspeed_in_void / Lightspeed_in_material !!!
> >>> this is the special case of an object standing in void.
> >>>
> >>> the real formula = lightspeed_in_first_material /
> >>> Lightspeed_in_second_material.
> >>>
> >>> if the light goes slower in the first than in the second, then the
> >>> ior is smaller than one.
> >>>
> >>> in the case of a bubble in water, the lightspeed is slower in the
> >>> water than in the air, so the ior is negative when the light
> >>> enters the bubble, and positive when the light goes out the bubble.
> >>>
> >>>
> >>> Daniel Barbeau wrote:
> >>>
> >>>
> >>>> ior_of_material  = Lightspeed_in_void /  Lightspeed_in_material
> >>>>
> >>>> Lightspeed_in_void is light's maximum speed. 300 000 km/sec If i
> >>>> recall well.
> >>>>
> >>>> Lightspeed_in_material can't be higher than Lightspeed_in_void, so
> >>>> ior_of_material can't be lower than 1.
> >>>>
> >>>> I guess this could be an Elysiun question and an Elysiun answer.
> >>>>
> >>>> Dani
> >>>> _______________________________________________
> >>>> Bf-committers mailing list
> >>>> Bf-committers at projects.blender.org
> >>>> http://projects.blender.org/mailman/listinfo/bf-committers
> >>>>
> >>>>
> >>>>
> >>> _______________________________________________
> >>> Bf-committers mailing list
> >>> Bf-committers at projects.blender.org
> >>> http://projects.blender.org/mailman/listinfo/bf-committers
> >>>
> >>
> >> _______________________________________________
> >> Bf-committers mailing list
> >> Bf-committers at projects.blender.org
> >> http://projects.blender.org/mailman/listinfo/bf-committers
> >>
> >>
> >
> > _______________________________________________
> > Bf-committers mailing list
> > Bf-committers at projects.blender.org
> > http://projects.blender.org/mailman/listinfo/bf-committers
> >
> >
> ------------------------------------------------------------------------
> --
> Ton Roosendaal  Blender Foundation ton at blender.org
> http://www.blender.org
>
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at projects.blender.org
> http://projects.blender.org/mailman/listinfo/bf-committers

```