Stream: brlcad

Topic: Sand Grains

Rahil Malik (Jan 07 2018 at 07:20):

How to model sand grains in Mged, i have to use them in the hourglass . Also if i could create a group or something related to that so there wouldn't be a lot of stuff in the ls command

Sean (Jan 07 2018 at 07:21):

clone or Pattern Tool

Sean (Jan 07 2018 at 07:21):

don't worry about what they look like (e.g., a regular or circular grid)

Rahil Malik (Jan 07 2018 at 07:22):

What about Gravity ? how to use that in mged ?

Sean (Jan 07 2018 at 07:22):

there's typically no problem with 10's or even 100's of thousands of objects in a database

Sean (Jan 07 2018 at 07:22):

that's a complex topic :)

Sean (Jan 07 2018 at 07:24):

This is out of date and requires a custom compile of BRL-CAD to even work, and may not even be working right now if it is enabled, but the "simulate" command turns on gravity: http://brlcad.org/wiki/MGED_CMD_simulate

Sean (Jan 07 2018 at 07:25):

it's the same system doing this: https://www.facebook.com/brlcad/videos/10155107336943873/

Rahil Malik (Jan 07 2018 at 07:57):

yea i tried doing the simulate command everything was good until at the last step , error said the build of brl-cad was not compiled with Bullet Support

Rahil Malik (Jan 07 2018 at 07:59):

What Should i do now ?

Rahil Malik (Jan 07 2018 at 08:40):

Kinda helpless !

Rahil Malik (Jan 07 2018 at 09:13):

So as Simulate doesn't work in my build of mged is there any else way to enable gravity ?

Lucas Prieels (Jan 07 2018 at 15:16):

I'm trying this task too but to make the sand, it takes more than two hours only to create and draw the spheres...

Siddharth (Jan 07 2018 at 15:17):

Same @Lucas Prieels

Jeff Sieu (Jan 07 2018 at 15:18):

Wow, so many of you doing this task

William Cook (Jan 07 2018 at 15:18):

Anyone help me on off-topic please.

Jeff Sieu (Jan 07 2018 at 15:19):

@William Cook What do you need help with?

Siddharth (Jan 07 2018 at 15:19):

Yeah, tell us

William Cook (Jan 07 2018 at 15:20):

Sec

Jeff Sieu (Jan 07 2018 at 15:20):

@William Cook try to post it under the correct topic ;)

William Cook (Jan 07 2018 at 15:20):

Look under no-topic

Jeff Sieu (Jan 07 2018 at 15:22):

So, what is the question here exactly?

William Cook (Jan 07 2018 at 15:23):

Im attempting to find the QT libraries. Are they downloaded seperate from the LibreCAD src files?

Sean (Jan 07 2018 at 18:11):

What Should i do now ?

I wasn't suggesting that you should run simulate -- I was saying that you should simply create a big grid of sand grains

Sean (Jan 07 2018 at 18:11):

@Rahil Malik that's basically just running the clone command maybe two times, or the Pattern Tool once

Sean (Jan 07 2018 at 18:11):

we can run simulate on it later -- it becomes a useful test case

Sean (Jan 07 2018 at 18:12):

I'm trying this task too but to make the sand, it takes more than two hours only to create and draw the spheres...

Rahil Malik (Jan 07 2018 at 18:13):

I don't understand, instead of cone, you want me to put sand grains(little) but cloning them and placing them at different places to make it look like a pile ?

Sean (Jan 07 2018 at 18:13):

I'm trying this task too but to make the sand, it takes more than two hours only to create and draw the spheres...

@Lucas Prieels that's because that's the wrong way. that's like the entire point of the task -- figuring out how to do it more efficiently than creating a bunch of spheres by hand. You need to create a million spheres ... so figuring out how to do that is kind of critical to the task.

Sean (Jan 07 2018 at 18:13):

@Siddharth ditto to you creating the sand grains wrong :)

Sean (Jan 07 2018 at 18:14):

@Rahil Malik no, they don't need to look like a pile -- they can/should be floating up in the air in the upper chamber

Rahil Malik (Jan 07 2018 at 18:15):

so a thousand grains in a single spot is Okay ?

Rahil Malik (Jan 07 2018 at 18:17):

@Sean as i can run the for loop and create 1000 copies of the grain at the same spot

Sean (Jan 07 2018 at 18:18):

in a single spot, no

Sean (Jan 07 2018 at 18:18):

that's invalid geometry

Sean (Jan 07 2018 at 18:18):

you create 1000 copies to place them in 1000 different spots -- the's the point of clone or pattern tool

Sean (Jan 07 2018 at 18:19):

you're basically doing something like this, without running the simulation: https://www.youtube.com/watch?v=k6nKC_DCh3o

Lucas Prieels (Jan 07 2018 at 18:32):

I'm trying this task too but to make the sand, it takes more than two hours only to create and draw the spheres...

@Lucas Prieels that's because that's the wrong way. that's like the entire point of the task -- figuring out how to do it more efficiently than creating a bunch of spheres by hand. You need to create a million spheres ... so figuring out how to do that is kind of critical to the task.

I'm not doing them by hand, I'm using a loop but it took approximately 10 minutes just to make one layer. Maybe I'm trying to do too small spheres

Sean (Jan 07 2018 at 18:36):

that still sounds horribly wrong for some reason...

Sean (Jan 07 2018 at 18:37):

I can create a million spheres in less than a second

Sean (Jan 07 2018 at 18:37):

what's your code/loop/script doing? paste?

Siddharth (Jan 08 2018 at 07:47):

We use cp sand1 sand2

Siddharth (Jan 08 2018 at 07:48):

that still sounds horribly wrong for some reason...

Doesn't take 2 hours to make the particles but placing them is a lengthy process

Rahil Malik (Jan 08 2018 at 09:41):

better than that type clone in command line, it will show you how to use use it , you can set a difference between each clone and much more, just type clone in command line and it will show you the usage

Rahil Malik (Jan 08 2018 at 10:02):

if you want patterns use this
http://brlcad.org/w/images/9/9a/Principles_of_Effective_Modeling.pdf
pg 73 (Appendix E)

Sean (Jan 08 2018 at 14:53):

that still sounds horribly wrong for some reason...

Doesn't take 2 hours to make the particles but placing them is a lengthy process

this is a process that does not scale to the number of particles needed. seriously, there needs to be thousands of grains of sand. the grains if modeled ACCURATELY (this is a CAD system after all) means there should be thousands or 10's of thousands of grains of sand.

Sean (Jan 08 2018 at 14:53):

so the question is how can you make all that sand without running cp 10's of thousands of times (isn't going to happen) and without placing each grain individually (which also isn't going to happen)

Sean (Jan 08 2018 at 14:54):

if you want patterns use this
http://brlcad.org/w/images/9/9a/Principles_of_Effective_Modeling.pdf
pg 73 (Appendix E)

rather, this was the right answer

vasugarg (Jan 08 2018 at 17:51):

@Jeff Sieu were you able to figure out anything ?

Siddharth (Jan 08 2018 at 18:57):

Woah, it seems simple now, never read this pdf before

vasugarg (Jan 08 2018 at 19:04):

?

vasugarg (Jan 09 2018 at 05:18):

@Sean did you have a look at what i posted ?

vasugarg (Jan 09 2018 at 05:19):

@sean can we continue where we left ?

Sean (Jan 09 2018 at 05:25):

@vasugarg what does it have to do with sand grains??

vasugarg (Jan 09 2018 at 05:36):

@sean i am getting confused

vasugarg (Jan 09 2018 at 05:36):

where should i post it

vasugarg (Jan 09 2018 at 05:37):

there are too many topics

vasugarg (Jan 09 2018 at 05:39):

also pls can you tell from where i should start explaining things ?

vasugarg (Jan 09 2018 at 05:44):

?

vasugarg (Jan 09 2018 at 05:50):

@**Sean can we start ?

Sean (Jan 09 2018 at 05:52):

@vasugarg you should post it on the topic that we were talking on before or start a new topic. using Sand Grains topic is just wrong, confusing, and disrespectful to others to keep using it for a different topic. please find your old topic or start a new one.

Siddharth (Jan 09 2018 at 07:34):

@vasugarg Why have you created more 3+ topics for the same task?

vasugarg (Jan 09 2018 at 17:08):

@Siddharth i haven't

Last updated: Jan 09 2025 at 00:46 UTC