   Curve caluclation
  Hi,does anyone know how I can caluclate a Curve in 3D???If I have for example 7 Coordinates where the Curve should go trough, how can I calculate the path of the Curve???Au''revoir,   Aya~ 
  see the catmull-rom spline aglorithm for that matter. The spline will pass through all the control points. http://www.mvps.org/directx/articles/catmull/ ;  Hi,thanks.. but, I don''t realy understand this.. And the D3D Example.. I can''t use this, because I can''t use D3D for my problem Could you explain me, how I can calculate the points by hand?? (also if I have more than 4 Points where the Curve should go trough)Au''revoir,  Aya~ ;  The formula for calculating the path is in the document Oliii posted the link to. If you calculate it by hand, you still have to understand the formula anyways. ;  Hi,ok...let''s take this row of the formula for example:[0,2,0,0] * [P0]What is  0,2,0,0??? It''s nowhere written in the Text... it''s just there, and I don''t know why... Au''revoir,   Aya~  ;quote:Original post by AyaKoshigaya    [0,2,0,0] * [P0]This looks like a vector-matrix multiplication (one row of that).Basically, at any point, the matrix defines at what weight the control points affect the function in any given parameter.Catmull-Rom interpolation has fixed parameter domain of 0 < t < 1 to be valid.I am not very good in explaining mathematical formulas, even if i know them, because i don't know the literal terms. Sorry  [edited by - Nik02 on August 3, 2003 10:24:49 AM] [edited by - Nik02 on August 3, 2003 10:25:35 AM];quote:Original post by Nik02  This looks like a vector-matrix multiplication (one row of that).Yes, but where does this Matrix came from??? 0,2,0,0.. i absolutly have no idea about that Au''revoir,  Aya~;quote:From Robert Dunlop's paper on Catmull-Rom splines:   q(t) = 0.5 *(    (2 * P1) +   (-P0 + P2) * t +(2*P0 - 5*P1 + 4*P2 - P3) * t2 +(-P0 + 3*P1- 3*P2 + P3) * t3)  This formula gives Catmull-Rom spline the following characteristics: The spline passes through all of the control points.  The spline is C1 continuous, meaning that there are no discontinuities in the tangent direction and magnitude.  The spline is not C2 continuous.  The second derivative is linearly interpolated within each segment, causing the curvature to vary linearly over the length of the segment.  Points on a segment may lie outside of the domain of P1 -> P2.  P0, P1, P2 and P3 are the control points thru which your curve goes. The matrix is only cleaner looking version of the same vector multiplications.I can't make it clearer than that, please read the article again.Kind rgds, NikEDIT: A matrix is representation of the influence of some vectors on some vector. (That's as good an explanation as i can think of.)   [edited by - Nik02 on August 3, 2003 11:00:01 AM];quote:Original post by Nik02  P0, P1, P2 and P3 are the control points thru which your curve goes. The matrix is only cleaner looking version of the same vector multiplications.Hi,yes.. P0, P1, P2 and P3 are the control Points...[0, 2, 0, 0] * [P0]here I''m multiplying a Matrix with P0.. right???Ok, so far it''s all clear, no problems... but i absolutly don''t understand why i am using [0,2,0,0].. why not [4,8,-2,0]?? I mean.. where does this Matrix came from???or is [0,2,0,0] the Coordinate of P0???Au''revoir,   Aya~ ;  The row marks weight values, with which you multiply the parameter and given control point to determine that given control point''s influence on the final result (or something, please correct me if wrong). Calculate for all control points, and you have the result. 