Point Expression into VEX

[Sepu]

Im trying to fake age like in particles with points I have solver which is making trails in points.

How you would transfer this expresion into VEX 

If you add this into POINTSOP - ADD COLOR on Red Channel this work.

1-$PT/$NPT

But I'm trying to make it work with a Point Wrangler and this is what I have. 

v@Cd = set(0,0,0);

@Cd.r = 1-@ptnum/@numpt;

Im trying o drive the age through color.

Then I would like to delete some of trailing as well.

So If I add A deleteSOP and I delete by an expression 

$CR>0.5; 

This also work.

But Im trying to do everything through the Point Wrangler or a Point VOP
 

Edited August 12, 2016 by Sepu

[3dome]

@Cd = set(1-@ptnum/float(@numpt), 0, 0);

for the delete part you have to do it after the solver.
the code would be

if (@Cd.x > 0.5)
{
    removepoint(0, @ptnum);
}

 

[Sepu]

That worked great, thanks so much!

Im definitely overthinking thing I guess. Now that I see the Vex code make a lot sense.

 

[Sepu]

Thanks, I was wondering how would you do the same with an Attribute VOP Im trying to understand, the way I can do it in both ways. This is what I got so far, but isnt working as expected

Thanks.

[Sepu]

Im almost there but  I have to issues it seems that the Attribute VOP my red color it has wacky numbers and the Attribute Wrangler is normalized and also why the points are not being remove?

Any ideas? Thanks 

Edited August 13, 2016 by Sepu

[3dome]

well, first of all you have to take care when dividing and subtracting. input order matters! your divide and subtract have wrong input order.
second, i told you you cant delete the points in the same vop/wrangle as you do the color work. you have to delete the points AFTER the solver.

top of my pic is the wrong setup (remove the deleting part), but color is right.
bottom is the delete part in a vop AFTER the solver

[Sepu]

Hey Dominik,

Thank you so much for all your help. I'm coming from Maya so Im still getting used to think in Houdini terms!

Figure out!

Again Thanks! 

Edited August 16, 2016 by Sepu