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Found 6 results

  1. Lets say you use c4d and you instance an object into different particles (with random rotations for example). If then you export that instanced geometry as an alembic and import it in 3ds max you get geometry with world transformation information (each geometry instanced has its own rotate/scale/translate info). Is it possible to do the same in Houdini?
  2. Hey folks, would there be a way to identify and extract, procedurally, animated rigid pieces from soft point deforming pieces? Say, you have a character alembic cache and several meshes on that character are rigid (i.e. their points don't change positions relative to each other). For example: the weapon of a warrior, or the plate armour, the shield... etc. I want to find those meshes procedurally and extract their transformations (and of course replace their point deformations with object-level transformations, duh...) Would you have a clue how to approach that? There wouldn't be a node for it already, would it? I'm thinking what heuristic to employ to differentiate between pieces which points do change positions relative to each other vs such that don't. Maybe just maybe... extract transformation matrices for every piece for some arbitrary prim, be it rigid or not multiply by the inverse to set each piece to the origin and... compute velocity in the result? all inversely tranformed points of rigid pieces have 0 velocity, some points (other than the points on the arbitrary prim from #1) of soft deforming pieces have v>0. tag them.
  3. Hello! I have this two models, one of them is an animated mixamo fbx of a character doing a spin-attack with a sword, and the other is a katana, the mixamo model doesn't have the sword, just the hand open like holding something. I isolated some points on the hand, got the centroid and created a point there, subtracted the position of two points in the palm and the transfered that vector as a normal to the central points where the sword will be, so its aligned to the hand, kind of. This worked for the first frame of the animation but get it comes to the spin the sowrd just keeps the same angle as in the first frame, the long of the sword is correctly oriented but the blade-side of the sword doesn't follow correctly the orientation of the hand. I'm still learning houdini and I for sure missing something and I don't know how to really look up for this anywhere else. Thanks. Here are some snaps: https://gyazo.com/f6dac5288ed223ac63a6ccea8b69fce5 https://gyazo.com/018df6bf2b990d3a9cd2cb8f2b0aff6b https://gyazo.com/0e6803c89574a2899cc7c4ecf005e8fa https://gyazo.com/1f886158016b065d9fca1400ffa4e380
  4. Drive Particles from Point A to Point B

    Hey guys, how can I do something like this but within a pop network? Thx
  5. Matrix Transformations

    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
  6. 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.