   unknown matrix
  Hey all. Another question. Lets say i have a model A and model B. I know that model B is just a copy of model A, but transformed by some matrix (this matrix 4x4 contains rotation about custom axis and translation).Now i'd like to calculate this matrix. How would one do that?So i have vertices from A and transformed vertices from B. How to calculate the matrix?   
  Do you know for each vertex which to which vertex in the other model it corresponds to?;  yes.   ;  Let P_a_i be a vertex from mesh A and P_b_i be a vertex from mesh B.Let T be our unknown transformation.We have that P_b_i = T * P_a_i for all i. Written a different way:| P_b_i_x |   | T_11 T_12 T_13 T_14 | | P_a_i_x || P_b_i_y | = | T_21 T_22 T_23 T_24 | | P_a_i_y || P_b_i_z |   | T_21 T_22 T_23 T_24 | | P_a_i_z || P_b_i_w |   | T_21 T_22 T_23 T_24 | | P_a_i_w |We want to solve for T, so we need more points. We can simply write these points as columns:| P_b_i_x P_b_j_x P_b_k_x P_b_l_x |   | T_11 T_12 T_13 T_14 | | P_a_i_x P_a_j_x P_a_k_x P_a_l_x || P_b_i_y P_b_j_y P_b_k_y P_b_l_y | = | T_21 T_22 T_23 T_24 | | P_a_i_y P_a_j_y P_a_k_y P_a_l_y || P_b_i_z P_b_j_z P_b_k_z P_b_l_z |   | T_21 T_22 T_23 T_24 | | P_a_i_z P_a_j_z P_a_k_z P_a_l_z || P_b_i_w P_b_j_w P_b_k_w P_b_l_w |   | T_21 T_22 T_23 T_24 | | P_a_i_w P_a_j_w P_a_k_w P_a_l_w |For some points P_a_i, P_a_j, P_a_k, P_a_l in mesh A and points P_b_i, P_b_j, P_b_k, P_b_l in mesh B. Now we can simply multiply by the inverse of the P_a matrix on the right side of the equation to get T.   ;  Then you can just pick any 4 vertices from your first mesh, create a matrix P that has those 4 vertices as columns, create another matrix Q that has the same 4 vertices form the second mesh as it's columns. The matrix which you want will then beA = Q * inv(P)   ;  thanks!   