   how to calculate normals and tangents vector?
  when we know the verticle's postion has changed according the following rule:P1 = P0 + V; where V is the transformed vector, P0 is the original postion vector and P1 is the transformed vector. If we know the normal and tangent of P0, then how to calculate the transformed normal and tangent of P1? Thank you very much.   
  If only the position of your vertices change by some delta v, then your normals and tangent vectors do not change at all.   ;  I forget to say the context.Just like a object(like cylinder),when it bend around its axis, all the position of the vertice on the cylinder will change, accordingly, the normal and tangent of the vertice will also change. So if P1 = P0 + V; where V is the transformed vector, P0 is the original postion vector and P1 is the transformed vector. If we know the normal and tangent of P0, then how to calculate the transformed normal and tangent of P1?   ;  It is not possible to compute the new normal and tangents only from P1, P0, and V. As dietepiet has already explained, the correspondence of P1 and P0 is a translation (by V) only, and that does not change the normal or the tangent. Either you're required to deal directly with the transformation that has produced V, or else you need to re-compute the normals and tangents from P1 and the other new vertices surrounding P1.   ;  I'm going to move this from Game Design to Graphics Programming and Theory sunrisefe. It's more appropriate and you may get many more replies there.   ;Quote:Original post by haegarrIt is not possible to compute the new normal and tangents only from P1, P0, and V. As dietepiet has already explained, the correspondence of P1 and P0 is a translation (by V) only, and that does not change the normal or the tangent. Either you're required to deal directly with the transformation that has produced V, or else you need to re-compute the normals and tangents from P1 and the other new vertices surrounding P1.From one paper, the author says:we can compute the Jacobian Jp of this transformation, then normals=Jp^(-T)normals and tangent=Jptangent. Maybe I will do a test.;  Yes you can compute the Jacobian provided you know the partial derivatives of the transform. And you can avoid computing the inverse of it when you transform tangent and binormal vectors and compute the normal from them.See the explanation in GPU Gems article about deformers.I used it in transformation by 3-axis fractal displacement and it works nicely.   ;Quote:Original post by cameniYes you can compute the Jacobian provided you know the partial derivatives of the transform. And you can avoid computing the inverse of it when you transform tangent and binormal vectors and compute the normal from them.See the explanation in GPU Gems article about deformers.I used it in transformation by 3-axis fractal displacement and it works nicely.thank you very much. It works.