[..Re-post because my original reply never seemed to show up...] "Jesper Knudsen" <[EMAIL PROTECTED]> writes: > It seems necessary to negate x-coordinates of meshes, if its matrix has > negative determinant. Can anyone explain why the designers of 3ds made this > 'special case'?
What do you mean "it seems necessary to negate x-coordinates"? IIUC, if a transformation matrix has a negative determinant, that means it encodes an odd number of mirroring operations. This means, for instance, that if you compute the normals of mesh triangles by using the cross-product of specific triangle edges, the normals of the transformed matrix will be flipped (if the original normals pointed "out", the transformed normals will point "in"). For some applications, that doesn't matter, I suppose; for others, it may. [This has nothing to do with lib3ds in particular, just a general observation.] -Miles -- Politeness, n. The most acceptable hypocrisy. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ lib3ds-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lib3ds-devel
