From: Tom Forsyth <tomf@mu...>  20020228 14:02:10

Yes, you need to animate them as well as the normals, and in the same way. Note that a shortcut that works suprisingly well is to only animate normals and tangent vectors by the most important (usually firstlisted) bone, rather than doing the full fourway blending. The difference in lighting is usually very small and hard to see, and it's a lot quicker. Alternatively, instead of animating the normals and tangent vectors, "deanimate" the light vector. It's often quicker in the simple case because there's only one vector to move, not three, but if you're also doing anisotropic lighting and all that sort of stuff, you have more "light" vectors to transforms and it can be slower. Also, depending on what animations you are doing, you may not be able to find the inverse of the animation matrices very easily. Tom Forsyth  purely hypothetical Muckyfoot bloke. This email is the product of your deranged imagination, and does not in any way imply existence of the author. Original Message From: Adam Moravanszky [mailto:amoravanszky@...] Sent: 28 February 2002 13:33 To: Algorithms List Subject: [Algorithms] Skinning + Tangent vectors Hello. I am completely new to mesh deformation with bones, so this may sound naive: If I have a mesh which needs tangent vectors per vertex (for bump mapping, for example) , should these be animated along with the vertex positions and the normals, or can that be avoided? Regenerating them from scratch every frame from the unchanging texture coordinates is too expensive??! P.S: I am doing skinning in software with Cal3D so this need not be hardware friendly. What I would like to avoid is rewriting my shaders to light in any other space than standard tangent space. P.P.S: I saw in the archives that this is supposedly covered in the book "Mathematics for 3D Game Programming & Computer Graphics", but alas, I don't have it. Thanks, Adam 