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Found 22 results

  1. Rotate pyro container

    Hello everyone, So the basic idea I'm trying to achieve is some geometry emitting a flame following a path. Not really difficult and I've got the basic version down. The trouble starts when I try to implement a rotated container for efficiency. My object doesn't travel at 90 degree angles on a perfectly aligned grid, that'd be boring! So why should I waste time simulating all that empty space? So what I've got is a geo node with a CHOP Network inside, constraining it to follow a path from a separate geo node. I create some velocities for my path-following, constrained object, then rasterize to volumes, as per the H17 workflow. Then in my curve object, I create orient data according to it's points, which I feed into a "Point Position" for my smoke object inside my DOPnet (I then drive it's "point number" parameter with a setup that determines the point along the path that is nearest my constrained object's center). Hooray, the container rotates along the path! Don't party yet... The point position node sets the "Position" data to pivot 0, and the translate data to match whatever "point number" it's looking at, causing the rotations to be applied around world center. But only for the incoming volumes, not the container. The container is positioned exactly where you would expect (perhaps because of the "Gas Resize Fluid Dynamic"). This seems kind of stupid, and I'm not sure when this would be useful. Maybe if the transforms were on the source volumes but NOT their containing object? I don't know. To solve this we next add an RBDState node because apparently it's one of the only other nodes that can write to the position data (THAT took a while to figure out). In the RBDState node we set the pivot to reference the translate of the original emitter (which is constrained to move along the path), and the translation (confusingly parameterized as "position") to zero, and set both of these parameters to "Set Always". Good god we're so close... But no. The container is correct, following our emitter's orientation along the path. The volumes are there too, centered where they should be, but wait... They're double rotated now. They get the rotation that's applied to the source volumes by the CHOP net in the object where they're created, AND the same rotation applied again from the "point position" node. I'm having a devil of a time with this. If anyone can help I'd be very grateful. There's another thread here: where someone managed to fix this by editing the old "Source Volume" node, but it doesn't seem to work the same way with the "Volume Source" node, or at least that I could discover. inverse_transforms_demo_4.hip
  2. I'm running a for-each-connected loop, and need to rotate separate shape such that the largest face is down, for example the one marked L is the largest for the shape in the image. I have a theoretical idea, no clue how to implement it, and not sure if there is a faster or simpler way: (1) get the largest face (no idea how) (2) rotate till the normal of the largest face is facing down Again it's too theoretical, but if you have a way that would turn these flat on they largest face I'll be grateful
  3. Hi, I am trying to set up controls for rotating the geometry created by polywire. I saw this post, but the scene doesn't work for me. https://forums.odforce.net/topic/25804-how-to-turnrotate-an-polywire/ I figured out how to gain some control by creating a local variable upvector and binding the joint up vector in poly wire to it. The part that confuses me is how to just create a slider that would allow me to continuously rotate, like in the example in my scene. Thanks in advance rotate_polywire.hiplc
  4. Hey, I have a line that I would like to transform in the direction of the curve. How can I rotate the pivot rotation to match the line? I am trying to match the Z axis to the line by rotation the pivot rotation y. Thanks
  5. I am trying to make a setup where I align an object orthographically and then after I do my operations move the result back to the original position. I have a working way for aligning but am sure there must be an easier way... My method for aligning now: - Create oriented bbox - Measure prims - delete all but largest, then delete 1 of the largest in order to just have 1 rectangle, 4 points - make a vector from point 0 to 1 to align with x - make a vector from 0 to 2 to align with y - make normals to align with z - in vops use the align vop to align the 0 1 vector to x then use the (rotated) normals to align with z Even though this works I assume (hope) there is a better way to find the vectors, using pointnumbers is not procedural enough imho so any tips here would be great. But then the part I can't seem to get... How do I rotate my result back to the original position? there must be a way to store the rotations and invert these or something but everything i tried didin't work. my vectormath and matrices could def use some work. ofcourse i can use a point deform but that would not be accurate enough plus i am 00% sure there must be a way to invert what i did in the first vop. Thanks!
  6. Twistet Stripe / Tape

    Hey guys, I'm trying to create twisted stripes / tapes like on this picture. I'm a beginner and know how to create a stripe out of a curve, but how can I twist it in a certain area? Is there a way to make it procedural? Thank you very much
  7. Particle rotate based in friction

    Hi guys I have a question that is breaking my headoff. I have a simple set up, I have a ground to collide and is scattering points in the surface , based in the distance threshold of an animated geo, I created a group based in an attribute, also have the N and v set up. From this group I'm creating particles to simulate some kind of debri left behind of the falling "rock". The particles when are born they rotate until they hit the ground, but not when are falling or "sliding" in the surface of the ground. I have a POPGraings that give me this nice falling/sliding look. Any idea on how to get the particles rotate based on the friction or contact with the ground surface? Thanks for any idea you can give me
  8. Hi guys I have a question that is breaking my headoff. I have a simple set up, I have a ground to collide and is scattering points in the surface , based in the distance threshold of an animated geo, I created a group based in an attribute, also have the N and v set up. From this group I'm creating particles to simulate some kind of debri left behind of the falling "rock". The particles when are born they rotate until they hit the ground, but not when are falling or "sliding" in the surface of the ground. I have a POPGraings that give me this nice falling/sliding look. Any idea on how to get the particles rotate based on the friction or contact with the ground surface? Thanks for any idea you can give me
  9. hi, I know how to do some basic rotations with vex although the objects is always rotation around itself. Is it possible to do the same thing but use an external rotation point e.g. one of the corners of the box ?
  10. Hi there, I have been trying to figure this out but probably don't know enough about transform/rotate matrices and how they work. What I got is a circle of flat boxes all orientated in Z. The flat side is always faced to the center of the circle. See attached image for better understanding. Now what I want is a rotation around the local X axis of each box. Attached is an example file to see what should happen and also what I have come up so far. To better illustrate what the end result should be there is the same setup built with a copy SOP and a transform node before to do the rotation. Now the solution I came up with kind of works. The main problem is that there seems to be some sort of scaling. You can see this when viewing the solution made in Houdini in template mode. Maybe someone can point me in the right direction. Also, my setup is not very elegant so if there are other or better solutions I would love to hear them. Thanks in advance! Dennis rotate_objects_local_v01.hiplc
  11. Frame of Reference _ Matrix

    Hi EVERYONE : Maybe this tutorial is not very short, watch it completely, i am sure that you find new stuff about matrix and you will learn new technique .Hope you find it useful !!! Hossam Aldin Alaliwi more training here : www.hossamfx.org
  12. particles path circle

    Hi guys! I've made a sim with particles but I would like to keep them rotate in circle for some seconds and then use their inherit velocity. how i can keep them rotating? i've been trying to add angular velocity with cos ($T * 180) ty = sin ($T * 180) this expression, but doesnt seem to work. any suggestions? thanks!
  13. DOPs Initial spin at event.

    This has been a very hard search to find an answer to. What I'm trying to do is add an initial spin/rotation to a DOP object. I attached a simple scene of a torus that has an initial upward velocity and then just falls to the ground due to gravity. Essentially, I'm trying to give it a "punch" that will cause it to spin - but not perpetually. A good example would be if you had an object that hit "glass." Although the sim would be physically correct, to add interest it would be nice to add a little spin force to the shards of glass on the initial impact. I can't for the life of me find a way to do this in DOPs. I'm sure I could be overlooking the most obvious parameter, but it's also Houdini and sometime the simplest task takes some finagling. Any help is appreciated! DOP_spin.hipnc
  14. I'm trying to mess around with orienting a particle's alignment to it's vector. Or a watered down version would be a cube on a path that follows it based on the particle's vector or velocity. Basically, orienting the particle to "speed space" if that makes sense? I tried mixing Normals and Velocity to possibly get them aligned but I'm pretty much lost. I took a look at @mestelahere to help me out, but I'm pretty much in over my head trying to do it in Houdini. I attached my file that is just a spinning circle with box's copied onto them. I was trying to make a simple scene where the boxes rotation matches it's vector. So nothing too out of the ordinary, but still kind of confusing. Thanks :)! velAlign.hipnc
  15. pre random rotation then orient.. hi!Some questions,just can`t get this effect in instance!could anyone help~!thx! rotate_in_copy_H15.hip
  16. Hi. Guys. I met a problem, There was a bent tube i want rotate it along itself. I make a sketch to help understand. D: The problem was i need do it by maketransform node of pointvop, i initial the pivot, but i can't set the rotate right. So if anyone can give me a hint will be great. Thanks. maketransform.hip
  17. Hi Folks! This is my first post here! I'm returning to Houdini after a break only to find that POPs have changed a lot... I'm stuck on one little thing - POPspin. I have a very simple AutoDOP network - (location - POPsprite - POPsolver) in POPsprite I have a VEXpression (spriterot = rand(f@id)*360) which sets the sprite angle to random. I want to give each sprite a slight random spin which I have tried to do with POPspin but I have had no joy! Should POPspin come before or after POPsprite? (at the moment neither works...) Any help welcomed, Thanks S.
  18. I want to copy objects on points and randomize them in rotation (e.g. Y axis) from 0° to 360° but in 90° steps. I think I need kind of an expression like " (round(rand($PT))*90)" but this gives me only 0° or 90°. I do not quite come up with the right solution for 360°. Would be nice to get some help with that. kind regards Jon rotateIn90degreeSteps.hipnc
  19. ROTATE PER PRIM HELP

    hi there, please help me with these, i have spend alot of week for these, and still stucked.. basicly i want to try to rotate perprimitive base, effected by color and rotate some degree..but yeah, im still alot of learning with these.. i have recreated on my daily tools cinema4d, and its just required some step to achive fx that i want...but for some reasond i want more freedom with those fx....so i jump to houdini... please anybody on these forum help me with these... i got help from official site houdini forum...and got helped..but still got error for the rotation... i upload all the file, from the refference video, and all the houdini file i created and got helped... thanks.. help please... the reff video: jk_rotate_with_n_124 (1)_helped.hipnc rotate_per_prim_needHelp.hipnc
  20. Per primitive rotation

    Hello everyone, I am trying to recreate the per primitive rotation example i found here with VEX for learning purposes. The example file uses VOP to calculate a quaternion to rotate the points but when i do it in vex something weird happens and points doesn't behave as expected. I have also used qrotate() but no luck. Can you please take a look at file? Am i calculating the quaternion wrong? Thanks in advance Per_prim_rot_vex.hipnc
  21. Copy SOP and Rotations

    Hi everyone. I'm hoping one of you clever people will be able to help me with this little problem I'm having. When copy-stamping objects onto some animated points, the copied objects are transformed along with the points, but they do not fully respect the rotations. I have a feeling the solution will require a vopsop, with some kind of vector math to get Y normal rotations, but my knowledge of vector math is very limited and I'm struggling to find an elegant solution. I've created a simple scene to demonstrate the issue. You'll see that the teapots do not rotate along with the grid that they are copied onto. Any help would be much appreciated! rotNotWorking.hip
  22. Hello! I am currently trying to wrap my head around being able to transform (rotate) instance objects for sop copy and instance rendering. Basic stuff, I know, but I'm stuck and my math suck. I have a hard time grasping dot product, cross product, matrices and quaternions -> 3D transforms There are, as far as I can see, a multitude of attributes and options to do this, and I am wondering what would be best suited for my use? Some use up, some use orient. Basically, I would like to have the rotation options of the transform sop (x, y, z rotate) to work on a point instance where the normal direction is the "up" direction (think teapots standing on a displaced ground plane, rotating planar to the ground when editing the y axis). I've been through a lot of examples but I just can't make them work for my scene. Either the objects are flipped or rotation is happening on the wrong axis or objects are not rotating smoothly, or I am not able to figure out how to "flip" to the right axis when using N and up (usually +-90 degrees in x) inside the vop. Most of all, it needs to be stable on deforming geometry. Any example of rotation working in this scenario would be most welcome! Also, if you have a link to a good (basic level) resource regarding this topic, that would be awesome! Thanks.
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