Emit Particles on Painted Attribute

[CinnamonMetal]

I painted a point attribute using the paint sop by naming the color (override color) a unique name. I  then copied the attribute using an attribute copy; but there are two problems.  The first is, how do I see the painted attribute as I can see when the paint sop is selected, from within the POPNet in the viewport ? Second, I want to only emit particles from the attribute which I painted using the paint sop; therefore the Emission type is set to, Scatter onto Surfaces and the Emission Attribute is the attribute name override which I created from within the paint sop, but the particles are not emitting strictly from that painted point attribute ?

[WLVL]

in the pop source, under source, make sure Scale Point Count by Area is ON.

This will prevent emission in areas where your emission attribute is zero.

 

to visualize the color check here:

https://www.sidefx.com/docs/houdini/basics/visualizers.html

 

[CinnamonMetal]

It worked, except; rather then only particles only emitting where I painted the attribute, there are particles emitting where I painted the attribute and the rest of the object ?

[6ril]

I kind of recall running into this problem, and solved it by specifying a SOP path instead of using the first context.

Not sure this is the same pb you have, tho

 

*EDIT*

Nah... it ain't the trouble, I just tried and it's all good in H18.

 

better post a .hip of your problem.

Edited March 30, 2020 by 6ril

[CinnamonMetal]

I tried your suggestion 6ril, unfortunately it didn't work as I wanted it; thanks  

[6ril]

you should post a simple .hip illustrating the trouble.

I just tried to emit from attribute, and it worked just fine. I used that new FANTASTIC attribute paint node.

Edited March 30, 2020 by 6ril

[CinnamonMetal]

The white particles are those emitting from the painted attribute; the rest I don't want ?

Fluid_Liquid_Sphere.hipnc

[Noobini]

here...see the difference when you actually POST your file ? this goes for all other readers too....c'mon....don't be shy in posting your file when asking for help.

Note the attribpaint.....not paint

vu_Fluid_Liquid_Sphere.hipnc

[6ril]

okm there's a few mistakes in your network.

If you check your spreadsheet with the paint node selected, you will see that you are not writing anything in the emitparticles attribute. It's all to zero. If you're with H18, use the ATTRIBUTEPAINT node, otherwise try to redo you painting, something seems odd there.

Also, you wired the attributecopy the wrong way around : you are telling it to copy @emitparticles from a node where it's not there to the node where you try to create it (failing paint node).

 

And mainly, to use the attribute feature in your popsource the emission type needs to be "scatter on surface". Otherwise the attribute field is ghosted, meaning it's not active.

 

I got it working just fine

[Noobini]

haha sorry i just got in 1 min b4 ya!!!

[CinnamonMetal]

2 minutes ago, 6ril said:

Also, you wired the attributecopy the wrong way around : you are telling it to copy @emitparticles from a node where it's not there to the node where you try to create it (failing paint node).

I did it the other way around so I could see the painted attribute on the mesh, when in attributeCopy or POPNet. 

 

3 minutes ago, 6ril said:

And mainly, to use the attribute feature in your popsource the emission type needs to be "scatter on surface". Otherwise the attribute field is ghosted, meaning it's not active

It was working when its set to points. I'm using H17.5.

[6ril]

 

2 minutes ago, Noobini said:

haha sorry i just got in 1 min b4 ya!!!

beaten by a noob  : /

 

[6ril]

1 minute ago, CinnamonMetal said:

I did it the other way around so I could see the painted attribute on the mesh, when in attributeCopy or POPNet. 

 

It was working when its set to points. I'm using H17.5.

you got the solution now tho ?

is attributepaint available in 17.5 ? (can't remember)

[CinnamonMetal]

When overriding color in the paint sop, shouldn't that give me a value; although if I create an attribute before the paint sop, I don't get a value for that attribute ? 

If I switch inputs of the attributeCopy, I see the attribute where the particles are emitting from in the viewport; otherwise I don't see it. 

Since your scene was created in H18, it doesn't work on my end.

[6ril]

switch to H18 it's free.

if you need to use the old paint to create @emitparticles :

you can go down a single line of nodes (no need for that attribute copy) :

attributefromvolume -> paint (and redo your paint from scratch in order to see some values in the spreadsheet for @emitparticles) -> popnet       it works.

 

And don't forget to switch the emission mode to SCATTER ON SURFACE. (you can untick the scale point count by area if you want)

 

Edited March 31, 2020 by 6ril

[CinnamonMetal]

Fluid_Liquid.hipnc