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adrian_graham

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adrian_graham last won the day on April 16 2015

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  1. Start keyframe animation on every particle event in maya

    Maya's particle instancer is a bit ancient, but you can do this. The limitation here is that you can't use keyframed animation; the instancer can, like its name implies, only instance a node or nodes, so the keyframe animation would be identical on all instances. What you'll need to do is: figure out how many frames of animation you need (let's say you have 10 frames of animation) for every frame, duplicate the sphere add all these spheres to your instancer node, note how they are ordered, this is important add an 'indexPP' per-particle float attribute to your particle on the particleShape, under the instancer options, set 'index' to 'indexPP' Now you can control which instance is shown via the indexPP attribute. Your task now is to animate this indexPP attribute when the particle hits something. Create a per-particle runtime expression on your particles like this: if( event && indexPP < 10 ) { indexPP++; } Adding an 'event' attribute allows the particle to know when it's collided with something. As long as it's 0, the particle hasn't collided with anything. See attached file. instance_sphere_anim.ma
  2. New Bifrost features which seem very powerful

    No, not for computations. Not yet, at least. However, we are heavily leveraging Maya's updated Viewport 2.0 OGS for display purposes. You can see this in those demos, showing fully lit and shadowed aero voxels or 50 million particles in the viewport without a hit in performance.
  3. New Bifrost features which seem very powerful

    I think you guys are on the right track. Aero (or aerodynamic) sims in Bifrost are FLIP-based, therefore are particle-driven, not based on a predefined grid. The sims, therefore, are not bound to any particular domain, unlike grid-based systems. There are two different simulations happening in the aero solver: the FLIP particles and the render particles. The FLIP particles drive the movement, are affected by velocity/collisions/accelerators, and the render particles are advected through the FLIP sim. You can have a low-res FILP sim and high-res render component, or vice-versa. Eventually, we'll be able to deform the render particles independent of the FLIP particles, so we can add detail, curl noise, etc. We can't do this just yet, but it's on our roadmap.
  4. New Bifrost features which seem very powerful

    Right now it's brute force, there's really no control over how those holes are exposed. Once the viscosity model is improved, however, this should become less of a problem, but we really need graph access to prevent this from happening in a sim such as this. If you made the pool (or petri dish, really) deeper, this wouldn't happen. Note the scale of that first sim is tiny; I think the initial drop itself is 4mm across, so this may happen in the real world.
  5. New Bifrost features which seem very powerful

    Oh, right, one more thing. You can get thin-sheet simulations within a liquid Bifrost FLIP simulation; there is a surface tension model built in (albeit a rudimentary one). Physical viscosity (which is coming soon) should help greatly. Here's a couple of examples: https://www.dropbox.com/s/j1upal7e64agu0c/milk_crown_slowmo.mov?dl=0 https://www.dropbox.com/s/yx8wyt0fj7jfbad/bifrostDropViscosityDrag.mp4?dl=0 They're both slow motion, and very small scale (to emphasize the thin sheeting). They also show the limitations of the current viscosity model, in that it's more like 'velocity smoothing' than anything else. But there's some surface tension anyway.
  6. New Bifrost features which seem very powerful

    Yeah, just google "flip bridson" and you'll get a ton of results. I should point out that it was Robert Bridson and Michael Neilsen who are the authors of the adaptive methods You can find all of Robert's publications on his page: http://www.cs.ubc.ca/~rbridson/ Robert has been a long-time collaborator with Marcus, as well as Michael Neilsen, who is also on the Bifrost team.
  7. New Bifrost features which seem very powerful

    Let me first answer this question by pointing out that the demos you see online are the 'Generalist Workflow' demos. We haven't posted the 'TD Workflow' videos yet, because we're still working on making the Bifrost graph a complete environment and overall nice place to work. We haven't shown delving into the procedural graph at all, which this group will want to see. If I could show you the inner workings of the graph (which I can't just yet), you would see there are different components of the graph, most of which run once per timestep. Within the liquid and aero graphs there is a compound that can be computed more than once, depending on various graph-step adaptivity parameters. In effect, this isn't dependent on time, but rather the solve itself. This iterator compound will run until certain conditions are met, independent of time step. EDIT: oops, internally, we refer to 'Time-Stepping Adaptivity' as 'Graph-Stepping' Adaptivity. But the important thing to note here is that only a portion of the graph is run multiple times, as opposed to the entire graph. Bifrost is decoupled from Maya, so Maya is, in effect, merely a client application (albeit one that's very well integrated with Bifrost). Bifrost has been designed this way so in the future we could run it on the cloud, on a renderfarm as standalone, from a client on an iPad, or, yes, perhaps if you're determined enough, via the various APIs from within Houdini.
  8. New Bifrost features which seem very powerful

    Hey guys, poking my head into this forum to hopefully answer any questions you may have pertaining to Bifrost, or Maya FX in general. I'm the Product Designer for Bifrost, working with Marcus Nordenstam, who is the Product Manager for Bifrost at Autodesk. Re: adaptivity, yes, the foam 'adaptivity' is kind of no big deal: just clipping based on camera frustum, and controlling emission based on distance from camera. This is not one of the killer features of Bifrost. There are many other types of adaptivity in the Bifrost solvers. That video link someone posted of Marcus showing spatial adaptivity is not a prototype, it's in Maya 2016. This type of adaptivity essentially lowers the tile resolution of large interior volumes that don't need high detail (ie deep underwater). When detail is added (via velocity field, collison, etc), the resolution is bumped back up to the finest level (like you see in the video: where the ship crashes underwater, there's higher resolution). There is also time-step adaptivity (which is only run during the particle/voxel transport stage), and graph-step adaptivity (which is run throughout the simulation). We're also working on other adaptivity tech in other areas. Basically, our mantra is "high resolution where it's needed, low resolution where it isn't", which extends to many areas of simulation and FX. Finally, the demos by Daryl Obert that were posted at the beginning of this thread are just that: demos. They're designed for speed and to show the basic usage of the toolset to the average user, which is definitely NOT this group. There is no smoke and mirrors, because he has the resolution dialed down fairly low to maintain interactivity. There will be other videos soon that will delve much deeper into the technical aspects behind Bifrost, which I think you guys will find quite interesting.
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