ParticleConstraint Usage

jonobr1

in Contributed Library Questions • 3 years ago

Okay, didn't totally understand this from the documentation, but here it goes. I noticed that all the object constraints for toxiclibs Verlet Physics ( ie SoftBoxConstraint, CylinderConstraint, etc. ) all interface with ParticleConstraint.

This is how all these objects apply the constraints?

Is it possible to interface our own custom shapes, say for instance an array of Vec3D points, with ParticleConstraint or would we have to build a custom shape out of the existing constraints?

—
http://jonobr1.com/

Replies(3)

toxmeister

Re: ParticleConstraint Usage

3 years ago

All these existing constraints don't interface with ParticleConstraint, but implement this interface. The definition of ParticleConstraint is simply this:

public interface ParticleConstraint {


  /**
   * Applies the constraint to the passed in particle. The method is assumed
   * to manipulate the given instance directly.
   * 
   * @param p
   *            particle
   */
  public void apply(VerletParticle p);
}

Using only an interface makes the physics engine much more flexible, since it doesn't need to care how a particle is being constrained by a given implementation. That's purely the constraint's concern...

So if your maths & physics skills are good enough, you can, by all means, define an entire mesh and use it as a constraint... You'll have to check for intersections/collisions and then are responsible to resolve them too. For meshes, that will involve ray-triangle intersections (see toxi.geom package) and back projecting points from inside the surface. You'll also have manipulate the velocity of collided/constrained particles or else you'll get havok. This all is something I'm very interested in myself, but not have had a serious go at yet...

jonobr1

Re: Re: ParticleConstraint Usage

3 years ago

Ah I see, thanks for clearing that up for me. Definitely more complicated than I had initially thought, but not too intimidating. First step is to get the array of Vec3D into Ray3D and create the mesh with the proper faces. I'm not familiar with 3D meshes (really only played around with Lee Byron's 2D Voronoi Mesh). Does anyone have any recommendations for online readings on the subject matter?

—
http://jonobr1.com/

fraguada

Re: ParticleConstraint Usage

2 years ago

Hello,
I have been quite fascinated by this library for some time. I am trying to achieve something based on the BoxFluidDemo, but inside a custom constraint. Are there any examples using a custom mesh as a constraint, or is the above suggestion the valid current answer?

So if your maths & physics skills are good enough, you can, by all means, define an entire mesh and use it as a constraint... You'll have to check for intersections/collisions and then are responsible to resolve them too. For meshes, that will involve ray-triangle intersections (see toxi.geom package) and back projecting points from inside the surface. You'll also have manipulate the velocity of collided/constrained particles or else you'll get havok. This all is something I'm very interested in myself, but not have had a serious go at yet...

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