Hi

I am trying to place a grid of particles on the an objects surface. Normally I would use PRT volume with the jitter turned off but as this geo is a bit complex and curved I am not getting good placement. I was wondering if anyone had a magama that did what PRT surface does but has the option to have no jitter.

Thanks

You can always “gridify” a jittery distribution, but then multiple particles might end up in the same location, affecting density.
youtube.com/watch?v=9rmOunBRKoA

You could also take a grid distribution and project it onto the target surface using nearest point or ray intersection.

Last but not least, if you have good uniform UVs on the surface, you could just convert UVs to surface coordinates to turn UV to XYZ (Z being 0.0 relative to the surface)

If you would post a screenshot of what the setup looks like, I might have a better idea.

Hi

as of now I dont have any flows. I was looking into this method that you did.
youtube.com/watch?v=QyNu2eGndhM

But I am getting similar issues as the image where there are gaps in the grid. The one is the grid is with prt volume and i have similar issues when i use birh grid from pflow.

Thanks

arches.jpg1024×1024 571 KB

The object is curved, but the grid is not. The Grid is normally in Object Space of the PRT Volume, unless the In World Space option is checked, then it is in world space. So if you have a curved surface, or even a slightly rotated plane, the particle grid might be under a shallow angle to the surface, and some particles might be in the shell threshold, and others outside. I just tested with a vertical plane rotated at 15 degrees about Z. A world-oriented PRT Volume from it with Shell of 1.0 produced vertical columns of particles with some of them missing, just like in your example. Increasing the shell kinda solved it, but it produced more columns behind the plane.

Once I rotated the PRT Volume at 15 degrees too, it produced the right result. But in your case, you cannot do that because there isn’t a single rotation, but the whole surface is curved in space.

Of course, you could draw a spline that follows that curve (or extract some edge to spline), and then try to Path Deform a grid created from a simple plane to get a regular grid with the same curvature as the mesh. You could then delete any particles from that grid that do not “see” a mesh via a ray intersection to remove particles that are inside the openings…

I recorded a video of a possible solution using the Path Deform approach. Krakatoa MX 2.6.1 with WSM Magma and WSM Delete is required.
youtu.be/zk5i0ib-hug

Note that if the mesh is too complex to extract a single edge loop from it, you can use the Section shape object to create a new one at a good height, then center to the mesh…

The resulting MAX file is attached (saved from Max 2015 as Max 2012 format):
KMX2_PRTVGridOnCurvedSurface_v003.zip (48.3 KB)

Thanks a lot. Most appreciated.

For now I just worked with the grid with a few gaps but I will have a look at this asap.