There you go buddy --> http://lmgtfy.com/?q=blender+tangent+space
On Sun, Nov 13, 2011 at 8:46 AM, Eugene Minov <minov....@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@blender.org > http://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers