5 ms·

Could this extend to 3D?

by Osmium 9y ago

striking 9y ago
It already does, for water effects.
- santaclaus 9y ago
  No one to my knowledge actually uses metaballs for surfacing fluids.
  - efraim 9y ago
    What is used instead?
    - dvt 9y ago
      Fluid simulation; see https://developer.nvidia.com/particles https://developer.nvidia.com/particles and https://www.youtube.com/watch?v=2gp7-ejkwBQ https://www.youtube.com/watch?v=2gp7-ejkwBQ Metaballs are way too expensive.
      - efraim 9y ago
        Metaballs would not be for simulating fluids but for creating the simulated fluid's surface. In your youtube link it would be a step between "simulating particles" and "meshed result".
        slavik81 9y ago
        "Fluid simulation" was a bit of a nonsense response to that question, but there are similarities between metaballs and fluid simulations. The kernel functions used to interpolate Smoothed Particle Hydrodynamics samples are basically the same thing as metaball functions. The main difference is that you probably don't need the isosurface during simulation. On a related note, one of the annoying things about metaballs for fluid surfacing is that there's some spooky action at a distance. Two drops of water will reach out towards each other as they come closer together, which makes no physical sense at all.
        dvt 9y ago
        Totally right. I meant to say "fluid dynamics," as in, approximating Jacobians, etc.
      - pdkl95 9y ago
        From the associated article for that video: > SPH ... with 500 000 particles ... about 2.5 fps on my GTX 1070 Still slower than what CNCD & Fairlight demonstrated in 2011 with "Numb Res", at 120fps (stereo 3D) on a geforce 280: > The demo features up to 500,000 particles running under 3D SPH in realtime on the GPU, with surface tension and viscosity terms; this is in combination with collisions, meshing, high end effects like MLAA and depth of field, and plenty of lighting effects https://directtovideo.wordpress.com/2011/05/03/numb-res/ https://directtovideo.wordpress.com/2011/05/03/numb-res/
winkerVSbecks 9y ago
¯\_(ツ)_/¯ you could probably make 3D bezier curves to generate the connector. The real iso-surface metaball definitely works in 3D.
knolan 9y ago
You can do 3D metaballs with Blender.
Ologn 9y ago
Like this? https://www.youtube.com/watch?v=wcdKHCp9foY https://www.youtube.com/watch?v=wcdKHCp9foY Works on Unix, Mac, iOS and Android Code mirror is here - https://github.com/Zygo/xscreensaver https://github.com/Zygo/xscreensaver W.P. van Paassen's metaballs C code is here - https://github.com/Zygo/xscreensaver/blob/master/hacks/metaballs.c https://github.com/Zygo/xscreensaver/blob/master/hacks/metab... Also, you can set various parameter tweaks for the metaballs from the command line or settings - count, radius etc.
kowdermeister 9y ago
Yes, there's a Three.js demo: https://threejs.org/examples/#webgl_marchingcubes https://threejs.org/examples/#webgl_marchingcubes
- Osmium 9y ago
  That's marching cubes though, which is different from the parametric/Bézier approach in the article?
  - kowdermeister 9y ago
    Marching cubes is the rendering technique, it's based on distance fields which is a similar idea to iso-surfaces. With the SVG/Bézier approach I doubt you could do 3D, true :)
thibaut_barrere 9y ago
Like this? https://youtu.be/RiHUKEEtzNE?t=3m48s https://youtu.be/RiHUKEEtzNE?t=3m48s (1997).
elihu 9y ago
Jim Blinn was doing that in the 80's. http://delivery.acm.org/10.1145/360000/357310/p235-blinn.pdf http://delivery.acm.org/10.1145/360000/357310/p235-blinn.pdf
Impossible 9y ago
My first experience with metaballs was in 3D as a feature in Truespace (https://en.wikipedia.org/wiki/TrueSpace https://en.wikipedia.org/wiki/TrueSpace) where they were used for modeling. In order to render a surface you have to either use a contouring algorithm like marching cubes to generate a mesh like the above three.js demo, or raytrace or raymarch them. Because metaballs describe a distance function, its really easy to use SDF raymarching and there is a whole category dedicated to metaball shaders on shader toy (https://www.shadertoy.com/results?query=tag%3Dmetaballs https://www.shadertoy.com/results?query=tag%3Dmetaballs).
deleted 9y ago
[deleted]

Could this extend to 3D?

by Osmium 9y ago

Could this extend to 3D?

striking 9y ago

It already does, for water effects.

santaclaus 9y ago
No one to my knowledge actually uses metaballs for surfacing fluids.
- efraim 9y ago
  What is used instead?
  - dvt 9y ago
    Fluid simulation; see https://developer.nvidia.com/particles https://developer.nvidia.com/particles and https://www.youtube.com/watch?v=2gp7-ejkwBQ https://www.youtube.com/watch?v=2gp7-ejkwBQ Metaballs are way too expensive.
    - efraim 9y ago
      Metaballs would not be for simulating fluids but for creating the simulated fluid's surface. In your youtube link it would be a step between "simulating particles" and "meshed result".
      - slavik81 9y ago
        "Fluid simulation" was a bit of a nonsense response to that question, but there are similarities between metaballs and fluid simulations. The kernel functions used to interpolate Smoothed Particle Hydrodynamics samples are basically the same thing as metaball functions. The main difference is that you probably don't need the isosurface during simulation. On a related note, one of the annoying things about metaballs for fluid surfacing is that there's some spooky action at a distance. Two drops of water will reach out towards each other as they come closer together, which makes no physical sense at all.
        dvt 9y ago
        Totally right. I meant to say "fluid dynamics," as in, approximating Jacobians, etc.
    - pdkl95 9y ago
      From the associated article for that video: > SPH ... with 500 000 particles ... about 2.5 fps on my GTX 1070 Still slower than what CNCD & Fairlight demonstrated in 2011 with "Numb Res", at 120fps (stereo 3D) on a geforce 280: > The demo features up to 500,000 particles running under 3D SPH in realtime on the GPU, with surface tension and viscosity terms; this is in combination with collisions, meshing, high end effects like MLAA and depth of field, and plenty of lighting effects https://directtovideo.wordpress.com/2011/05/03/numb-res/ https://directtovideo.wordpress.com/2011/05/03/numb-res/

winkerVSbecks 9y ago

¯\_(ツ)_/¯ you could probably make 3D bezier curves to generate the connector. The real iso-surface metaball definitely works in 3D.

knolan 9y ago

You can do 3D metaballs with Blender.

Ologn 9y ago

Like this? https://www.youtube.com/watch?v=wcdKHCp9foY https://www.youtube.com/watch?v=wcdKHCp9foY Works on Unix, Mac, iOS and Android Code mirror is here - https://github.com/Zygo/xscreensaver https://github.com/Zygo/xscreensaver W.P. van Paassen's metaballs C code is here - https://github.com/Zygo/xscreensaver/blob/master/hacks/metaballs.c https://github.com/Zygo/xscreensaver/blob/master/hacks/metab... Also, you can set various parameter tweaks for the metaballs from the command line or settings - count, radius etc.

kowdermeister 9y ago

Yes, there's a Three.js demo: https://threejs.org/examples/#webgl_marchingcubes https://threejs.org/examples/#webgl_marchingcubes

Osmium 9y ago
That's marching cubes though, which is different from the parametric/Bézier approach in the article?
- kowdermeister 9y ago
  Marching cubes is the rendering technique, it's based on distance fields which is a similar idea to iso-surfaces. With the SVG/Bézier approach I doubt you could do 3D, true :)

thibaut_barrere 9y ago

Like this? https://youtu.be/RiHUKEEtzNE?t=3m48s https://youtu.be/RiHUKEEtzNE?t=3m48s (1997).

elihu 9y ago

Jim Blinn was doing that in the 80's. http://delivery.acm.org/10.1145/360000/357310/p235-blinn.pdf http://delivery.acm.org/10.1145/360000/357310/p235-blinn.pdf

Impossible 9y ago

My first experience with metaballs was in 3D as a feature in Truespace (https://en.wikipedia.org/wiki/TrueSpace https://en.wikipedia.org/wiki/TrueSpace) where they were used for modeling. In order to render a surface you have to either use a contouring algorithm like marching cubes to generate a mesh like the above three.js demo, or raytrace or raymarch them. Because metaballs describe a distance function, its really easy to use SDF raymarching and there is a whole category dedicated to metaball shaders on shader toy (https://www.shadertoy.com/results?query=tag%3Dmetaballs https://www.shadertoy.com/results?query=tag%3Dmetaballs).

deleted 9y ago

[deleted]