point clouds, vops and creating edges

[magicU]

Hi all, I've just been diving into learning about Point Clouds and I've been trying to dissect examples to figure out what's going on..

 

I've been looking through Matt Estella's "Create Edges with Vops" file:

 

http://www.tokeru.com/cgwiki/?title=Houdini#Create_edges_with_vops

 

and whilst I'm able to replicate the effect, I'm wondering if it's possible at all to access the points on the floor that are being connected to the floating soot points. What I'd like to do is make the ones on the floor which are being connected, to change colour to red, but then go back to being black once disconnected. So far, I'm thinking that in the current setup this can't be done,since it's the soot points that are being queried? A thought just popped into my head- Would the way to go about it be to scrap the initial group check, sampling everything and only checking for groups later when calling add-primitive & add-vertex?

 

Thanks for any pointers... 

[mestela]

Yep, you can set the value of another point with setpointattrib(). 

 

I just did some relearnin' of point cloud funcitons, this time with vex rather than with vops, I think its easier to read. Here's the guts of it (the wrangle has its group dropdown set to only run on the body points) :

 

float dist = ch('dist');
int num = chi('num');
int pc = pcopen(0,'P',@P,dist,num);
int pt;
int prim;

@Cd = {1,0,0};  // set body colour red

while (pciterate(pc)==1) { 
  pcimport(pc, 'point.number',pt);
  if (pt != @ptnum) {   // the results will include ourselves, skip that
      prim = addprim(0,'polyline');
      addvertex(0,prim,pt);
      addvertex(0,prim,@ptnum);
      setpointattrib(0,'Cd',pt,{0,1,0},'set');  // set foot colour green
  } 
}

And a hip file:

 

soot_colours.hipnc

 

 

-matt

[mestela]

And a silly variation based on the plexus stuff Atom mentioned the other day.

 

spiders.hipnc

 

[sebkaine]

Now i know how those lazy animators at ILM has animated the War of the World mecha ...  

[magicU]

Amazing! Thanks Matt. I just knew there'd be a function somewhere to access that info.

 

VEX has suddenly jumped up a few places on my to-learn list... though I think the new un-nested loops in VOPS do help with reading "code" a bit..