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Showing results for tags 'transformation'.
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Hello every one, I've been studying some linear algebra to better understand this amazing piece of software called Houdini. I came across some problems and after some RnD I've put together an example scene that I hope can be usefull for every one struggling with matrices and other related concepts. I feel the need to share this, because most of the tutorials I've seen on this subject end up using quaternions for the transformations, and I've put up a Matrix only approach. Do remember that the "correct" approach in this cases is the quaternion one. If any one is kind enough to convert this scene into a .hipnc and re-share it, I'd be grateful. At the moment I don't have time to do it myself. Cheers! Matrix_Transform.hip
Lately I have been trying to wrap my head around transforming point positions with the use of matrices in VOPs. To do that, I tried the following: Lets assume I have 3 points with their position vectors A, B and C which come from an alembic and are constantly changing values. I use a time shift and set it to $F + 1, and extract the same points position vectors, which are now called D, E, F. Then I set A,B and C into a 3x3 matrix, transposing it (to get the vectors in columns instead of rows) and do the same with D, E, F. After all this, I multiplied the inverse of the matrix containing ABC with the one containing DEF (this was not inverted). The resulting matrix was multiplied with new Position inputs, but the resulting transformations didn't match the original ones... What am I doing wrong? Thank you.