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Found 19 results

  1. Hey guys, new here, nice to meet y'all! I'm new to Houdini and have been dabbling with VEX recently. It's a love hate thing. Being interested in social insects I got the idea to build a little "ant robot" that could follow a trail. It has a body (point) and three points that serve as sensors. These sensors sample the ground's trail attribute (red, works), compare their values, find the "winner" (works) and then the whole thing should rotate accordingly and move along a vector that goes from the body to the best sensor point to stay on track. (Works not so well). That's the status and at least it's doing some following the path, but I can't get the robot thing to rotate around a custom position. Instead, the matrix rotation always uses the world origin as a pivot which looks increasingly bad with distance and at a certain stage just breaks. Also, the body promptly severs itself from the rest, which is a tad unfortunate, as I wanted it to follow the sensors (stay attached) and serve as a the pivot for the rotate(). I know this is a little messy but maybe one of you would like to have a look at the hip and point me to the obvious mistakes I made. Much appreciated! Cheers, Felix Robot_movement_issue.hiplc
  2. Hi everyone, I'm trying to create a delay effector style effect on some copied boxes, but I've chosen the option to pack primitives before copying and now in CHOPS I want to know how to make say a Spring CHOP pick up the rotation of a packed prim. Here is an example scene file below. Thanks to anyone who can help. C4D_mograph_rebuilding_01.hip
  3. I have a popnet creating some particles with the POP spin, to have a random rotation in each particle, also Im copying a tube in each particle, the tube rotates as it supposed to, but when they hit the ground, the tubes stays with a random rotation as well instead of pointing Y. I'm thinking that if I use the normals instead of the POP spin I could blend between the N0 and N1 when the particle hit the ground, using the hit info from the POPnet, but truthfully I don't know how to achieve this .-. I'm using POPs and copy the tubes/coins to the particles because the particles born magicaly from the floor after a character hit the floor with his cane. If anyone could help me or have any idea I would appreciate it!!!
  4. I was testing to transfer particles from Houdini to Maya,i use Cortex plugin to go into Maya,since Maya default importer sucks like 3dsmax roadmap So i was triying to get rotations, so far i cant get to work. Anyone tried this? Thanks
  5. VDB rotation using VEX

    Hello everyone. Got a question about vex rotation for VDB objects. I've got a FLIP setup in which there is a model of a ship moving forward and rotating slightly. I created rotation control using VEX code. Very simple version of it looks like this: //Rotate object along X axis; this is just for an example matrix3 m = ident(); float angle_x = radians(ch('Angle')); rotate (m, angle_x, {1, 0, 0} ); @P *= m; This works for regular objects just fine. However, I want to use VDB version of the ship for collisions. When I apply this code to VDB object it doesn't work. I need VDB object to move and rotate as the original model exactly. So the question is - How can I transform this code or write a new one to rotate VDB object exactly as regular model?
  6. matrix rotation issue

    Hi, I am trying to give little banking in my flying object.......so i have created a 3 by 3 matrix,gave an angle and an axis in the direction of velocity....and then used it in vex as a rotate matrix.... vector axis = normalize(@v); vector matx = cross(axis, {0,-1,0}); vector maty = cross(axis, matx); matrix3 m = set(normalize(matx),axis,normalize(maty)); float angle = fit(sin(@Time * 0.5 + fit(random(@ptnum),0,1,0,360)),-1,1,-45,45); @angle = radians(@angle); rotate (m, @angle, axis); @orient = quaternion(m); i want to know is there any way to print the value of rotate matrix?? i did the same thing in vop sop and its working but here i face some issue. what's wrong i didn't understand.
  7. Hi guys, I've been giving VEX a go recently and I've hit a block in something I'm trying to achieve. I'd like to take a set of points from a scatter node and wobble or wiggle each of them randomly on a given axis (Y) over time. As an expression this is as easy as sin(time * #) in the rotation transform for a desired axis. This doesn't work in VEX as everyone knows. I did find a lot of reference on matrix and quaternion functions in VEX and this seems like the way it should be done. It looks pretty complicated though for something as simple as wobbling a point on an axis. I know VEX works with radians only. Anyway, I'm sort of stuck. Any help would be appreciated. Thank you!
  8. Copying Constraints?

    I am super stuck on trying to create constraints across multiple copied geometry. I attached my file to make more sense of it. If you open the DOP Network you can see that from left to right I have a position constraint>rotation>rotation. However, I'm confused on why the second rotation constraint isn't connecting to the 1st. It acts as if it's just a position constraint with a rotation constraint on it. Hopefully my file explains more. It's kind of a mess because I tried to copy the constraints across instead of making a new line each time. Trying to learn the most basic form of using constraints so any help is much appreciated. constraint.hipnc
  9. RBD stylish collapse

    Hi guys I'm trying to simulate two tall buildings destruction like the attached image. So I fractured my entire blue building and the wing of the red building and I made a lot of constraints with different strength and break forces. The plan is to make it stylish that the blue building collapse as height of the green rectangle and the wings of the two buildings fracture apart and few pieces in entire buildings. But in all different situation that I tried, the blue building starts to rotate counterclockwise after colliding with the red wing. So do you guys know how should I approach this problem? Thank you in advance
  10. Hi, I'm trying to do a simple A to B transformation like this from Rohan Dalvi .But I wanted to do more so I want the object to mach perfectly. I separated it in chucks using voronoy and packed it using assemble sop. I did the animation I want but I when I copy back to chunks I don't get the rotation of the points. When I do it with copy sop it works fine. I will send you this file with a demonstration. MORPH_POINT_POS.hiplc
  11. Hi guys, I found 2 ways to export points in maya using RF plugin and otl. https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=141806 Maya reads particles, but I can't force them to rotate. I Created rotationPP attribute in maya and assigned different vectors, for example: particleShape1.rotationPP = particleShape1.rfNormalVector but each of them doesn't look like if I use copy sop in houdini. any Ideas?
  12. Hi guys. I'm trying to get point rotation around local axis (around local Y axis) I need to export points in Maya later, so I can't use copy sop for stamping. If I use transorm sop with Copy Stamping I can rotate Objects along local axis, but if I'm trying to edit rot and orient point attributes points are rotating in worldspace (around world XYZ) not along local axis. If I use orient attribute points are aranged in worlspase, not along normal. Can sombody help with that, please? ps I found Make Instance Transofm Vex node, but 'Ive got no Idea how to use it >__> point_rotation_001.hip
  13. hi everyone. i make the angluar velocity in SOP. and inheritied Point velocity in DOP. (i was modify RBD Packed Ojbect DOP like H14. this allow Overwirte attribute.) but, doesn't rotate in simulation. what made the wrong w attribute or i missed something??? i shared my hip. thanks for your read. have good day! w_attribute.hipnc
  14. Glue Wire to Animation - no rotation!

    Hi all, I'm trying to make som plants stick to a moving rock and deform with wire constraints, and have some issues getting the animated rotation to work with wire constraints.. Hopefully you can help me out. The curve is parented to the animated object and made it in to a wire object using the "Wire Object" shelf tool. Then I used the "Glue Wire to Animation" and selected the lowest point on the plant curve to get the animation in to the DOP network. The translation works perfect but the animated rotation doesnt seem to work at all, and the wire keeps a constant orientation. Probably this is how it's supposed to work...but I can't figure out how to get the orientation from the animation in to the DOP network. Anyone? I've attached a simple .hip file RND_GrassTwigs_v01.hip
  15. Hi. Follow the white \\ \\_ .-----( ' ). o ( ) _ - \_ => https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=38999 to read the rest. Thanks!
  16. Hello there, can anyone tell me how to set up random rotation of particles in houdini 13? First I would like to have the particles have a random rotation on creation. I haven't been able achieve this in the file attached to this message, so I tried to do this in sops using the copy sop and transform. However, doing this seems to create some weird kind of snapping behaviour. Isn't there a good way of doing this in the particle sim? Second, i would like the particles to have a random rotation over time as well. I've used the torque node for this, but there are some problems. For example, the torque accumulate over time (I think), so it tends to start from a low angular velocity and then goes higher. Attaching a drag fixed the issue of too high speed, but not the issue of too low in the beginning. How can I control this better? And then I tried to use vexpressions, which I know next to nothing about. I seem to only be able to control one of the axis with my expression. Controlling axisx, axisy and axisz failed... What am I doing wrong? I would appreciate any help! Thanks, Doug particle_rot_problem.hipnc
  17. Hi, How to find rotation angles between two vectors? Lets say Vector A = {0, 1, 0} and B = {1, 0, 0}, the angle between these vectors is 45. We can find this angle by using combination of dot product and inverse cosine. But I would like to know the rotation vector like {45, 0, 0} Thanks for your time
  18. Pop align to ground when hit

    Hey all, I'm playing with Pop to create a confettis setup. I had some difficulty to figure out how to make particles align to the collider object when they hit. I did some test with a vop pop and playing with orient attribute but I had problem mixing 2 orientation together, the vop node is still there but inactive. I've linked a scene so if someone can have a look, that could be nice. Thanks Doum Confettis_falling.hipnc
  19. Hello, I'm looking for the equivalent to the pops nodes rotation, velocity, and attribute in dop pops, trying to simply convert a H12 to H13 setup. Not sure if this need be an RFE, or if there is an equivalent already there. Thanks -Ben
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