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hmihalis1

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hmihalis1 last won the day on May 26 2019

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About hmihalis1

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    Harry Sanderson
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  1. save particle velocities every frame

    Hi All, TL;DR - How do you save particle velocities each frame to feedback into a sim? I'm working on a particle effect for rain on a window. Currently adapting a nice example from Toadstorm. I've made some changes to his setup. He has new particles growing over time and becoming droplets past a certain pscale, so i've derived mass from pscale to connect droplet size and speed, as the wind force i'm using to move them is not set to ignore mass. video I added a sop solver after the DOP to delete still particles touched by moving ones. And a popinteract and a popfluid to try and get the moving drops to coalesce and follow each other as they move down, but this has only slightly worked. Ideally i'd like to write the velocities of the moving drops into a volume which could then come back into the sim the advect the particles, or some other technique that follow make it so that new drops hitting and existing trail would follow its path precisely, and add a little to their speed and size. I presume I would use a sop solver inside my DOP network for this, but no clue beyond that. Any advice much appreciated, H windowdrops-uv3-w.mp4
  2. Kill particles by distance

    I combined your code and this seems to have the desired effect: f@distance = (float)abs(length(v@startPos - v@P)); if(f@distance > ch("distance_threshold")){ @dead = 1; } will make sure to set up the groups properly. still new to pops and getting my head around streams etc
  3. Kill particles by distance

    Ok thanks it seems to work kind of but also deletes points i want to keep so i'll try your solution now
  4. Kill particles by distance

    Hi @Noobini Thanks for your response! Right now I have this situation: //Rounding my particle age up to get the frame number (no idea if this maths is right): f@frameAge = ceil(f@age*24); //if frameAge is 1 save the startPos: if(@frame == 1){ v@startPos = v@P; } //Then get vector length and kill if it exceeds threshold: f@distance = (float)abs(v@startPos - v@P); if(distance > ch("threshold")){ @dead = 1; } Do you think this makes sense? Not confident i'm getting the vector length correctly. I'll check your solution now. Thanks so much!
  5. Kill particles by distance

    Hi all, I'm trying to come up with some vex to use to kill particles in a sim when they have traveled a certain distance from their birth location. I have mother particles that last one frame and i'm using a pop replicate to spawn new splash particles from them. What i'd like to do is store the position of the mother particles and subtract it from the position of each replicated particle every frame to get the distance, then set them as dead once this has passed a given threshold. Extremely limited VEX experience here, so if anyone could give me some kind of starting hint/snippet that would be amazing Many thanks, H
  6. Hi all, I'm trying to come up with some vex to use to kill particles in a sim when they have traveled a certain distance from their birth location. I have mother particles that last one frame and i'm using a pop replicate to spawn new splash particles from them. What i'd like to do is store the position of the mother particles and subtract it from the position of each replicated particle every frame to get the distance, then set them as dead once this has passed a given threshold. Extremely limited VEX experience here, so if anyone could give me some kind of starting hint/snippet that would be amazing Many thanks, H
  7. Hi, reformulating my question from my previous post: If I have a VOP net animating the positions of a plant mesh with a noise, how do i blend back to a rest position at the end of my frame range so that the animation loops? I've tried the blend shapes node with a time shifted version of the noise but i don't get any transformation.
  8. Thanks @anim that worked perfectly!
  9. Hi, I want to set the value of a parameter based on the value of a switch node, so if switch is 0 set the parameter to 1, if its 1 set the parameter to 10. Could anyone help with this? currently I am trying if((ch("../switch1/input")=0,1,10) could anyone tell me where im going wrong? thanks
  10. UVs for procedural corals

    amazing thanks so much - i'll give it go
  11. UVs for procedural corals

    Thanks @AslakKS, do you mean to smooth the low poly VDB? should I try to make it slightly bigger than the highpoly one?
  12. UVs for procedural corals

    Hi there, I'm making some proecural corals for a game engine situation using VDB advection: so of course the highpoly models need to be reduced and have normals and height etc maps baked, but i'm having a bit of a nightmare trying to find a auto UV solution that can create Uvs that don't contain errors, see below a baked AO texture resulting from auto UVs, the errors are even more noticeable on the normals channel: Could anyone advise me on what settings to try in the autoUV SOP? I'm currently using the UV autoseam, I tried cluster but its just crashing my machine. It doesn't matter if it takes an hour+ to generate the UVs for each coral, or should I just abandon trying to autoUV shapes this organic and weird? UV maps are always very confusing for me. Any help at this time is hugely appreciated, H
  13. Hi there, I'm working on adapting this effect to grow crystals on an animated character. so far I have created a color map which drives the density of the crystals, which i've bound to a mesh_density value fed to a remesh node to remesh the body of the character with bigger polygons at the centre and smaller ones as the color falls off, then divided it to get hexagons and extruded them out using some VEX that i've just guessed at, the zscale is calculated from the mesh_density but remapped a bit, and with some randomness applied: My main problem now is how to de-intersect the extruded geometry. I was thinking I could use a measure SOP in the loop and all the crystals into a large group and a small group, then cut the ones in the small group off wherever they intersect a larger crystal. Once I have this done the plan is to take the crystals in the large group and extend the loop for them so they can cut off at random angles at the top+some additional details as explained in the CGMonkey/Entagma tutorials covering minerals. So my questions are: 1. How to check for intersections in extruded geometry and bool a smaller group from a larger group 2. How to make the VEX in this wrangle better so I can control the random heights and fall offs with values and curves. 2. Will point deform work to stick this geometry back onto my animated creature? To be clear, my effect is a static encrustation of crystals on this lizard which is animated, I don't need to figure out the crawl on animation in the above video. Any help is very much appreciated! Thanks, H crystal_growth_001.hipnc
  14. Hi there, I have what I'm hoping is a simple thing for someone with a little vex knowledge. I'm trying to adapt the adhesion force in the condensation shelf tool to be driven by a gradient or noise on the mesh instead of applying the same amount of adhesion force all over the mesh. I have made a custom attribute called 'friction' with a gradient and some noise, clamped the values between zero and one and exported it: Unfortunately I am not nearly clever enough to understand how to adapt the VEX in the DOP Network to take this into consideration: Right now the particles that hit the floor get pulled back up to its neck. Ideally I would like the this friction attribute to remap whatever value is entered in "strength" so that in the red sections adhesion force is whatever is entered there, scaling to zero as it approaches the black. Been struggling with this for awhile but vex is a real wall for me so would really, really appreciate it if someone could be so kind as to help me out here Thanks! H friction-adhesion01.hipnc
  15. Wire solver from moving lines

    Hi, I'm trying to figure out a saliva effect and am currently looking at the strands of saliva connecting the top and bottom of the gums and mouth of the creature tgats been animated and brough originally as an alembic (now cached to houdini geo) I've got points scattered correctly on deforming geomettry, then used point deform and add to connect the points, and have been following the entagma connect the yarns tutorial to resample the lines and set the mass for the connecting points to 0. However when I try to go to the next step using a POP network I can't figure out how to have the POP source update the lines and am only able to simulate movement if I create them on the first frame. Is there a mrelatively simple way I can get these lines and their anchor points into a DOP or POP network so I can simulate them to add some movement? I'm looking to mesh them and add then to some drool that im trying to put together using the condensation shelf tool. Any help is greatly appreciated EDIT: figured out the simulation using vellum thanks to Rohan Dalvi, although if anyone could give advice on how to mesh these look close to the strands in this video that would be amazing:
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