Birth Particles, Row By Row

[abvfx]

hi guys, got a quick question.

I want to spawn particles in a certain way.

Imagine a polygon sphere, all points deleted $TX >= 0 and $TY <= 0. So it looks like a quarter of a sphere.

Then i flatten that geometry with a point sop, TY = 0.

So there is this flat half circle, with the edges going in a half circle.

How do i spawn particles so that they happen row by row. Right now i cant do it, it based by point number so its basically spiraling.

Plus i would love to birth more than one particle at each vertex. I dont know alot of OP's in Pop's so if you could point me in the right direction, im happy to read the help file.

cheers

-andy

[old school]

If you start out with a sphere as a mesh, then you can append a primitive SOP > Face/Hull folder > Vertex: Swap U and V.

Append your Convert SOP to convert to Polygons.

Then follow up with a SortSOP and in the Point folder sort based on vertex.

These should be inserted right after the sphere SOP.

You may be able to insert the Sort SOP _after_ the Delete/Blast SOP so you don't have to redo that.

[old school]

Birthing more than one point per vertex is trivial. Use the min and max birth probability in the Source POP to birth more than one particle per point.

In the Source POP > Birth folder > Birth Probability 10 10 would give you minimum 10 and maximum 10 particles per second if you are using continuous and that number per timestep if you are using impulse activation.

Use the min and max birth probability to birth more than one particle per point.

[abvfx]

cheers mate, i will try that out and post the results.

I think this will be a pretty cool effect if i get it right.

thanks again

-andy

[rjpieke]

Another possibility (if I understand your "row by row" request correctly), is to apply a Sort SOP on your flattened geometry and sort by proximity to the centre of the circle.