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Everything posted by gaurav

  1. DOP group exprresion

    IMHO, $OBJ is local variable for any dop object's position in current order of dop objects being processed. I could be wrong but don't think its possible the way you are wanting it. However, Individual dop objects can be part of multiple groups. Here is a rather simple way to split single wire in to multiple pieces / groups and control forces on them. wireGrp.hipnc Cheers !
  2. Fast smoke simulation

    Hi, Quick setup attached to illustrate the idea. Give it a go. fastGas.hipnc Cheers!
  3. Hi Guys, Long time Sharing some of the Fun Effects work done about a year ago for Dreamwork's Boss-Baby. Sorry for WIP takes, I don't have final renders. Cheers!
  4. Old vs 'new' PopNet

    Some correct me if i am wrong. They are also much more Memory Efficient, earlier pops were linked lists in memory.
  5. CG Short film, WIP

    Very Cool Adam ,very Cool !
  6. Spray(whitewater) collision

    You may ask How did bunker figure that out ? with experience of course. But if you are new to Dops best place to look for this info is details view. Important thing to remember is that Merge node in dops doesn't merge multiple data streams in Sops sense but it creates relationships. Relationship data is the one that tells dops dynamic engine which object affect which other object. Affector Matrix(Table) in dops Details view is very useful in figuring that out. Top row is of Affector objects and left col is Affected objects. Green color is two way, Blue is one, and grey no color means no relationship. If you hove rover cells you get the popup text. Play around with different Affector relationship types on Merge node to see how it reflects in this table. Cheers !
  7. Hey Guys, I have a situation with flip sim where every time i write out / cache there is a change in particles positions in some areas of sim. My scene particles have somewhat moderate velocities with wide variation in viscosity ranging between (0.000 to 1.000)*40 in few decimals places. Although overall sim shape remains the same but there is a visible change in secondary shapes, fine tendrils it makes. My suspicion is on the viscosity solver as i bypass viscosity calculations the error goes away. 64 bit float precision doesn't help the case either. I am aware of rounding errors that are inherent in floating-point computation but have no idea of how is viscosity solved. Has anyone experienced it behaving it non-deterministic ? Thought to ask around before submitting as a bug. H14.xx.xxx Thanks,
  8. Minute Houdini Tips

    Hey Guys, Long time ! Tried my hand at creating short Houdini Video tip under 5 minutes. Had fun doing it. Hope it proves useful to someone Cheers !
  9. hundreds of tiny bubbles in FLIP

    Hi, Wanted to share something similar tried a while ago. Bubbles are generated as johnny described but test rendering was all together. Indeed the more control at comp the better. Cheers!
  10. Hi Guys, To avoid guesswork from multiple open session with %>ps -a | grep ..... How do you access PID of a session *Being inside the same session* ? Tried looking for env var in %>hconfig -a with little luck. Thanks,
  11. Two ways in wrangle 1. append v before @side rotate(rot, rot_mul ,v@side) 2. or declare before using as variable. vector side = v@side; rotate(rot, rot_mul , @side); Cheers!
  12. Unique Linear Algebra Book

    With Interactive Figures ! https://youtu.be/TIcSnsmitHw http://immersivemath.com/ila/index.html#
  13. POP kill in flip fluids?

    Turn on Reap Particles found on Flipsolver > Particle Motion > Behavior tab
  14. Minute Houdini Tips

    Hip attached , HTH, gm_contained_FLIP_fluid.hipnc
  15. Minute Houdini Tips

    You are welcome Try increasing particle radius scale. .05 is too low i believe defaults is > 1. Cheers!
  16. Hello Folks, What are some preferred methods of extracting transforms from the sop level and apply them at the scene level ? Something like what rivet does. But how can i access transformation matrix which rivet generates ? I need to transform another obj only for a frame at the obj level as per the orientation of geo inside the sop. Reason being, I dont want to parent my obj to rivet and need it only for a frame to position/orient another obj at scene level. Right now i have very crude way of doing it, Would like to hear how pros do it. Thanks,
  17. Vine Around Trunk?

    Here is another simple approach for generating twisting vines around center core /trunk, keeping dynamic animation in mind. Sorry for untidy file never had time to clean it up. wire_solver_capture01.hipnc Cheers!
  18. Houdini world is divided into those who use quaternions and those who are going to use them Now say you want to rotate Normals for point num 0 1 and 2 by 45 degrees around X axis. Laydown attrib wrangle enter @ptnum == 0 1 2 in Group field and following in VEXpression field : float angle = radians(45); vector axis = set(1,0,0); vector4 myQuaternion = quaternion(angle,axis); @N = qrotate(myQuaternion,@N);
  19. Newbie Transform Node confusion

    try following in tx ty tz fields eval(chsraw("../xform3/tx")) eval(chsraw("../xform3/ty")) eval(chsraw("../xform3/tz"))
  20. Hi Guys, Missing some basics here.. I want to be able to Visualize force vector field from, lets say Gas Vorticle Forces (using vector field viz) and Modify ( gasfield vop/wrangle) it pre solving step. How do I go about doing it ? Thanks, -GM
  21. Extracting Transforms

    Hey Guys, Sorry been off lately.. I think I used optransform() vex function in inline to fetch transforms of given object and passed returned matrix to extract transform vop. HTH, -GM
  22. Sorry for cross posting. No replies make me question the legitimacy of the question itself. I am new to it.. May g...OD help 1. With Stochastic transparency optimization turned on. Is it possible to set the number of transparent rays per pixel ? 2. Stochastic transparency turned off : Opacity sample image plane is shows 0 samples per pixel. Why is that ? Thanks in advance, -GM
  23. Check out siggraph 13 course Parallelism in Houdini for deeper insights. http://www.multithreadingandvfx.org/course_notes/