I have a chance at my dream job. During my interview it was suggested to me to study POPs and ROPs as much as I could… So that is what I have been focusing on. I am having some trouble with some of the POP legacy material. Specificaly the color pop, render pop, and mantra. I have been working on the POP_fire_4_pdf last night and after appending a color pop and making the suggested changes I could see the update in open gl with no problem. Then I went to render with view mantra as noted and all I got were a bunch of white blobby spheres and no alpha ramping as expexted. The tutorial stated that I should see the color changes and the alpha effect. I tried debugging this for a while before moving on…. Am I missing something or should this tutorial work straight out of the box. Any suggestions would greatly be appreciated as I have had a similar problem in a previous tutorial… Thanks In Advance Todd

Hi Todd, congrat on your chance at your dream job.


As far as passing the color of the particle out, you can do that in your SOP network. So in your SOP network, you have the POP SOP, and another geometry that you want to instanced to your particles via Copy SOP. In your Copy SOP, go to the Attribute tab and turn on “Copy Template Point Attributes” If you know specifically that you want the Cd ( Color Diffuse) attribute to be copied, than type in “Cd” in your Set column on the “To Point” field. THis will copy ONLY the Cd attribute, nothing else. If you want all your attributes to be copied, just leave the * as it is.

Now, if you have a shader assigned to your geometry, you won't need to to do anything else because the Shader can pick up the Cd and convert it to diff attribute to assign it to shader. Only a few VEX SHOP will accept this. So I think the best thing is to rename your attributes to something else so that all shaders will pick up the color. Thus you'd append an Attribute SOP, and rename from “Cd” to “diff” and voila.

Hope that helped.
Alex

I followed all your directions and learned and relearned some things. In my viewer everything looks great (opengl) but within mantra still white spheres.. Could I have messed up the rop settings? I am still at a loss.. Gues I will now focus on the bombing exorcies… Thanks Though… I am sure that once I become more familiar with pops I will figure it out. There isn't any way you would post a pop to sop with your recipe.. It would help me debug this thing alot thanks…

Hey Todd,

See if the following work. Below here is a small hscript command example that I wrote – since I can't attach files in this forum. Just copy and paste this into a plain text file and rename your file and extension to my_script.cmd (you can name whatever filename you like) and put it somewhere.

Then, inside Houdini, open up a textport and type this to run through the commands:

source <my directory path>/my_script.cmd

Look through the POP (popnet1) and SOP (tmp_geo) network. In the viewport, you won't see any color at the moment – that's fine. Do a simple test render out at some frame and you should see some color on the sphere.

ANyhow, I Hope this help.
Cheers,
ALex








#Passing POP color EXAMPLE to SOP for mantra.
#BEGIN
echo Begin sourcing…

echo Creating and setting POPs in POPNET1…
opcf /part/popnet1
opadd location tmp_location1
opadd color tmp_color1
opwire tmp_location1 -0 tmp_color1

opparm tmp_location1 vel 0 1 0 var .2 .9 .2
opparm tmp_color1 cswitcher 2
opramp tmp_color1 0 .357 .23 1 1
opramp tmp_color1 .3 1 0 0 1
opramp tmp_color1 .57 1 .96 .52 1
opramp tmp_color1 1 1 1 1 1

oplayout
opset -C on -d on -r on tmp_color1


echo Create a temporary obj and necessary SOP…
opcf /obj
opadd geo tmp_geo

#Now go into tmp_geo
cd tmp_geo
rm *
opadd pop pop
opadd sphere sphere
opadd copy copy
opadd attribute attribute_rename
opwire sphere -0 copy
opwire pop -1 copy
opwire copy -0 attribute_rename

opparm sphere rad .1 .1 .1
opparm pop popnet popnet1 pop __cook_pop__
opparm copy doattr on setpt Cd
opparm attribute_rename frompt0 “Cd” topt0 “diff”

oplayout
opset -C on -d on -r on attribute_rename

echo All done.
#END OF FILE

When I get home tonight I will definately, try this out… Can't wait…. It is so nice to have a user base with such willingness to help newcomers… Thanks

Alex again I am blown away by your kindness and willingness to help me… Honestly, I have been studying Houdini Aprrentice since August/September 2002… I put a second on my truck to buy a kick ass HP system with a nvidia 900 gxl board simply to learn Houdini…. It is everything I always wanted in a graphics app…. I try to get in an hour or so a day…. Currently I am a fulltime employee at a commercial post facility in west hollywood. Ring of Fire…. My title is Lead Motion Graphics Artist/ Special Effects Artist.. Some title uh… Well I basicaly assit the inferno and henry artist with the things that they can't do or are simply below them…. Don't get me wrong they are great artist and great friends that have taught me alot… but when I got my first taste of Houdini I felt like iggy from taxi in the episode where tom hanks brings some pot brownies to a havard dorm room and Iggy (Ignakowski) first gets stoned.. I had that kind of high and I never turned back… Sometimes going through the legacy material gets frustrating, because there are little differences that don't quite equate… I think I get something but what the !@#$…. When I post someone always comes to my rescue…. I know that once I get it I owe the next generation of newbies some support… Thanks your file totaly works and is exactly the type of bench mark I need to debug my setup…


I wish I could say I fixed my file but I went to a designer friends house tonight for drinks and conversation… See January 31 is my last day of employment at Ring of Fire and I will enter the crazy world of Hollywood (although all the coolest shops and boutiques are in Santa Monica, Venice and the Westside) for the first time in 3 years… So I have a little networking I got to do from time to time… And tonight was one of those nights.. I am home now but its almost 1 am and I have had a bottle of wine… So my debug skills are a little blurry so tomorrow night… I will get the file working…


Sorry for the personal rant I have had a bottle of wine…. And I am very grateful of your time and help… I also surf oddforce on a daily basis… I know that you can post links there… I just took your code and pasted it into the textport and viola perfection… Thanks Todd

I love your saying at the end of your signature… Did you make that up? Awesome Philosophy! I feel that way everyday now that I face the unknown cash flow….

Hey there, Todd.
It's a pleasure to help however I can help. (You can never get tired of seeing that spark of joy when it clicked in their head. )


Wow. Honestly, Todd, you're doing far far better than I am. When I first started Houdini back in version 3, it was a struggle for me to trying to figure things out on my own – especially when I barely have any knowledge of 3D at all. :wink:
I still have so much more to learn at the moment. :shock:

As far as legacy material is concerned, they are still a great for learning the workflows of Houdini – through the Network of course. In a lot of the legacy material, you won't be doing much with your viewport other than viewing your objects. You'll be doing most of your stiff through the Network Editor. It's great fun.

Take care,
Alex

Ok, sorry if this is insulting in any way, but sometimes it's important to check thebasics:

Did you apply a shader that takes accepts point colors and alpha? You'll always get plain white if you have no shader on the object at all. Try using a VEX Super Material.

To be perfectly honest with you the code that the usualAlex supplied allowed me to get the expected color out of the color pop without any shaders in sops..

On a secondary level.. I personaly have not gotten into Shops, texturing and lighting yet.. Although, I have been following some post on odforce dealign with a GI hack in vex with some tricky shader compositing… I just have not gotten to outputting images yet.. I think that I am still too wraped up in the entire procedural modeling, CHOPs and now playing physics with POPs is just blowing my mind… I was just having some diffiuclties and have not been able to get to it until tonight 2:00 am california time… Last night I was out on the smooze tonight I tried chasing the wife around the apartment… You know priorities… I redid the fire pop legacy tutorial and implemement alex's sop network and everything worked perfect… Again It was so nice of him to help me out… Tommorrow I move on to flocking…. and beyond…