[Bf-committers] Blender tangent space calculation

Eugene Minov minov.eug at gmail.com
Mon Nov 14 00:41:24 CET 2011


Oh, my bad :) I've seen that page but I'd thought this page is explains
different baking modes in blender's render.

Morten Mikkelsen - thank you for your great implementation! I'will learn it!
M.G. Kishalmi - thanks for explanation )

On Mon, Nov 14, 2011 at 1:55 AM, M.G. Kishalmi <lmg at kishalmi.net> wrote:

> Eugene,
>
> the link Morten pointed you
> to<http://wiki.blender.org/index.php/Dev:Shading/Tangent_Space_Normal_Maps
> >explains
> that
>  the tangent space you created your normal maps in (in blender)
>  is generated by the implementation in
> mikktspace.h<
> https://svn.blender.org/svnroot/bf-blender/trunk/blender/intern/mikktspace/mikktspace.h
> >and
> mikktspace.c<
> https://svn.blender.org/svnroot/bf-blender/trunk/blender/intern/mikktspace/mikktspace.c
> >
> .
>
> you might want to use those in your app (check the licence inside).
>
> cheers,
>  lmg
>
>
> On Sun, Nov 13, 2011 at 10:51 PM, Eugene Minov <minov.eug at gmail.com>
> wrote:
>
> > Wow!! Thanks a lot, for pointing me to the google ;)
> >
> > But I afraid that maybe I've not correctly describe my problem. If so,
> > sorry for that, because my english is still kinda weak.
> > My problem not in generating a normal maps (a textures) in blender. Not
> at
> > all.
> >
> > My problem is that I cannot fully correct render my already generated
> > normal maps in my app. Because, how I mentioned in the last mail, the
> usual
> > methods for this purpose (by UV coords) is not gives me desired results.
> >
> > So I wanted to ask for help with information about methods blender uses
> for
> > generating tangents.
> >
> > And yes, I had searched in google but unfortunately have't found
> something
> > helpful yet.
> > If someone can point me to that kind of info, I will be very grateful!
> >
> > On Mon, Nov 14, 2011 at 12:08 AM, Morten Mikkelsen <mikkelsen7 at gmail.com
> > >wrote:
> >
> > > There you go buddy --> http://lmgtfy.com/?q=blender+tangent+space
> > >
> > >
> > >
> > > On Sun, Nov 13, 2011 at 8:46 AM, Eugene Minov <minov.eug at gmail.com>
> > wrote:
> > >
> > > > Hi.
> > > > I am sorry if I subscribe into a wrong place, I am new and I've not
> > > > actually planned to change or to debug the blender sources yet.
> > > > But I trying to write app that'll be render models with normal
> mapping
> > > > exported from blender, and I have a question about how exactly is
> > blender
> > > > calculates a tangent vectors when Unwrap operation in the editing
> mode
> > > > performs?
> > > >
> > > > Calculating tangents in my app in usual manner (using UV coords and
> > verts
> > > > positions) gives me different tangents for each face of the same
> vertex
> > > > indexed from, and thus crumpled normal map looking.
> > > > Then by looking into blender sources (searching  by 'tangent'
> keyword)
> > > I've
> > > > found a couple of functions with tangents calculations, like:
> > > >    float axis[3] = {0.0f, 0.0f, 1.0f};
> > > >    cross_v3_v3v3(tangent, normal, up);
> > > >    normalize_v3(tangent);
> > > >
> > > > After I tried same method in my program I've gotten almost perfect
> > > looking
> > > > model, depending on what initial axis I've used.
> > > > To choose, which axis to use (0, 0, 1), (0, 1, 0) or (1, 0, 0) for
> each
> > > > normal, I calculate max dot product of tangent calculated by each
> axis
> > > with
> > > > tangent calculated from UV coords.
> > > > But still it seems that in some rare vertices tangent is calculates
> > > wrong,
> > > > maybe because of wrong initial axis.
> > > >
> > > > So, can anyone please give me any information about tangents
> > calculation
> > > > formula that blender uses while generates UV coords or some advice
> > about
> > > > choosing initial axis.
> > > > Thanks for help.
> > > >
> > > > Eugene
> > > > _______________________________________________
> > > > Bf-committers mailing list
> > > > Bf-committers at blender.org
> > > > http://lists.blender.org/mailman/listinfo/bf-committers
> > > >
> > > _______________________________________________
> > > Bf-committers mailing list
> > > Bf-committers at blender.org
> > > http://lists.blender.org/mailman/listinfo/bf-committers
> > >
> > _______________________________________________
> > Bf-committers mailing list
> > Bf-committers at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-committers
> >
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at blender.org
> http://lists.blender.org/mailman/listinfo/bf-committers
>


More information about the Bf-committers mailing list