View Full Version : How to stop the grass growing/going through the object?

04-12-2007, 01:55 AM
Hey guys, i created a field of long green grass, but when i place an object like a chair or a table on the field, the grass went through the chair and table, how do i stop it from going through other object? is there a object collision function in lightwave? thanks!

My scene is not animated, it's a still image!! thanks in advance

04-12-2007, 02:34 AM
what sort of grass? Poly modelled or Sasquatch?
If poly, you can do it in Layout with a Pole deformer and 2 Null objects to control the falloff and strength, or in modeller also with the Pole tool.
With sasquatch you can, as far as i remember use null objects to press down the grass.

04-12-2007, 03:13 AM
I used Saslite for the grass in layout, and what's a null object? how do i create it or implement it into my scene?

04-12-2007, 03:30 AM
Hmmm...maybe you should open up the manual for a bit (and i don't mean this belittling), because that's a very basic but very often used 'dummy' object, it looks like a 3 axis cross.
But, you can create them using <CTRL> + <n> or via the menu Load/Add -> Object -> Null (Studio Production Menu preset)

In other software these are used for a multitude of functions aswell, also often referered to as a Gizmo or Locator.

04-12-2007, 07:40 AM
Well, i checked outt he manual and i think i got the gist of it, well a little anyway, so, do i place an null object onto the area (where the grass is) and it will flatten them? and than place my chair onto the same spot where the null object is? can some one please en-lighten me on this? thanks,,

also, i have another question, this is layout/endering related, For a few of my objects(like 20), i used the 'weight map' to sharpen the edges of my Sub-d models, but when i opened it in layout, it looks like a blob, how do i fix this problem? one of my object still maintain its crease edges because i used 'Band saw' instead of weight map. But i can't afford to use band saw to sharpen the edges for all my models, it's too costly(time, polygons and major slow down). Is there anyway to fix this problem?

One last thing, some of my objects looks very blocky in layout but not in modelling,! i checked the surface editor and have all the smoothing for all the surfaces turned on, anyone know what the problem is??

i know i have been asking heaps of questions, but i really do appreciate and grateful for all the help from you guys! many thanks in advance!

04-12-2007, 10:06 AM
- Better to make the null a child to the chair so you just have to move the chair and the null will follow.

- On the object properties panel, select last as the subdivide order and that should help alleviate the blobbies and the next issue of the blocky look, as well.

04-12-2007, 07:57 PM
thanks Grafx, how do i parent the null object to the chair? i looked up the manual but it's all about parenting the bone and the meshes, and not object to object, thanks

04-12-2007, 08:25 PM
Mah friend,
Do you have the software? If so, GIVE IT A GO!!! ;)P

I only say it that way because parenting works betwixt them all: lights to cameras to objects to nulls to ... all around.

Be brave in your interactions with LW. My biggest problem when I started was forgetting that this was all digital stuff and I could save it to come back. To that end I was AFRAID to try stuff. Don't be afraid, my friend, mucking up is good for the learning process.

Go out and muck it up!!

04-13-2007, 04:00 AM
Hey guys, i parented my null object to the chair, but how do i get it to press down the grass?? i turned on the dynamic 'FX collison' and 'gravity' in properties manual, but it's not presseing down the grass,
i ahve 3 layers now, 1 for grass, 1 for the chair and 1 for the null object in layout, i parented the Null to the chair, but some how it's not affecting the grass, any ideas?

04-13-2007, 04:05 AM
Also, i used saslite to genrate the grass and it looks very blocky, is there a way to make it look smooth? here is a pic of what i'm talking about,( http://img187.imageshack.us/my.php?image=grasscu0.jpg )
i played around with the options in Saslite but i still couldn't managed to get the grass looks smooth! please help! thanks!!

04-13-2007, 06:55 AM
Mind sharing your scene?

04-13-2007, 08:01 PM
I'm too embarassed to share the scene file, there's nothing much(details) to it really, just a field of grass, just an old chair and a table. I used Saslite for the grass and it's very long, that's the look i want but it's going right through my chair and table! i can't seem to fix this problem,

here is what i did, i loaded my scene in layout, with 3 layers,layer 1 is grass, layer 2 is chair and layer 3 is table, I created the grass for layer 1 using Saslite, than i created a 'Null object' and it got its own layer, so now i have 4 layers.

I placed the Null object right ontop of the grass and than i placed the chair on top of the null object, i than parented the Null object tot he chair, after that, i opened the Properties menu for the Null object, i turned on the collision FX and Gravity FX, i didn't change any of its setting and left everything as default, so when i rendered it, the grass still poking right through my object!!

any advice? many thanks in advance