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About Sean-R

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    Sean Rowe
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  1. Sticky FLIP on moving Object

    There are a couple of VEX functions you can use to help stick particles to an object, volumesample() and volumegradient(). You will have to convert your cherry geometry into a vdb to make it work. Multiplying the returned values together (and negating the volumegradient) and adding the result back onto the particle position. The code should be put in a POP wrangle and looks like this: @vs = volumesample(1, 0, @P); v@vg = volumegradient(1, 0, @P); @P += @vs * -@vg; The "1" means to look at the POP wrangles second input, which I've set to the cherries vdb. The "0" means it's looking at the first primitive of that input. @P is the current position of the particle This should work with both pops and flip. I've attached a hip file trying to recreate that gif you linked. the above setup can be found in the DRIP_SIM section cherries_colliding.hipnc
  2. @Atom - Ah yeah you're right. I've attached a file with the point deform in the correct place to get your group to work with your new geo groupOnRemeshedGeo.hipnc
  3. You can use a timeshift set to the frame you set the group on and then use a point deform against the deforming mesh to get your point consistency back. How have you prepared the mesh? It would be better to go back and fix the swimming there.
  4. How to create curves from particle fluid?

    I'm not sure what you mean. That was straight from the sim, do you mean the points from the trail?
  5. Patronus Charm Effect

    You can control the glow and fade away in a shader. The prinicipal shader has an emitint and an opacity scale parameter which you can drive attribute, like age.
  6. How to create curves from particle fluid?

    Here's one way, I could get quite heavy though. I checked "Add ID attribute" in the flipsolver node, connected a trail to the flip particles and chose how long I wanted the stream to be. Then I dropped down an add node, set it to group by attribute and set it to ID
  7. Explosion effect with particles

    Bit late to the party but thought I'd throw together a quick and dirty setup. Scatter some points on a sphere. "Group" together areas of points using the cluster sop. Colour the points using the cluster attribute created in step 2. Set up initial velocites in a pointvop, randomised with a noise. Sim with some variation added to the initial velocities to break up the shape. Emission is only on for the first frame. Trail the sim to a frame that you're happy with in regards to explosion size. Use a point replicate to bump up the number of particles* Use a VDB from particles node to create a density and Cd volume. * I wanted more control over the pop replicate node so I added a UV attribute which then drives the uniformscale parameter. It needs a fair bit of tweaking to get to that top picture but should get you off to a good start! particleExplosion.hipnc
  8. Bullet Going Through a Mechanical Heart

    I would just animate the bullet and treat it as a collision object. If you absolutely have to sim the bullet then I would treat it as two sims, one with just the bullet, then with the bullet as a collision object for the heart.
  9. Dry sand, density of initial grains

    Have you checked out this page? http://www.sidefx.com/docs/houdini/grains/stablepile.html
  10. Persistent Point ID on Changing Topology

    Try this in a wrangle: @id = @ptnum;
  11. Flip Fluid Collision Problems

    Looks like you need some thickness, use a polyextrude to create a thick barrier around the cup. Then in the dopnet, check the Collision guide under the Flip Fluid Object node to see it's true representation
  12. Loop over prims and delete

    Ah, I'm not too savvy with Python so can't help you there. If you want to do it in vex you would probably want to do this in two nodes. The first one would be the same as you have there but instead of using the removeprim() you can either create a group or set and attribute. Something like this: if(@Cd > chv("Color")){ @group_deleteMe = 1; } ; You would then do the deleting in a second node, either by using a Delete node set to "Delete By Range", or by another if statement in a wrangle: if(@group_deleteMe && rand(@primnum) < chf("threshold")){ removeprim(0, @primnum, 1); } ; Hopefully someone can help with the Python side of things!
  13. Loop over prims and delete

    Then you want to compare the @Cd attribute with a vector, either with a hardcoded vector like in my original code or a channel like you set up with the slider attribute. So: v@minCd = chv("minCd") @Cd > @minCd What are you setting your slider attribute to? If you set the rmprimitives channel to something like "1" it ill only delete primitive 1.
  14. Loop over prims and delete

    Have a read of the removeprim() help, you are currently manually selecting which prim to delete with that slider attribute. @primnum calls the current primitive that is being run through the code, it will then delete that primitive if it matches the if statement.
  15. Loop over prims and delete

    Ok, if you only want to select the red prims and not the purple/pink ones then try this: @Cd.x>0 && @Cd.y+@Cd.z == 0