LookAt constraint for trees in max?

ShaunDon · February 20th, 2004

Hey guys --

I've got a quick question... I'm trying to simplify some RPCs into planes with a LookAt constraint to keep them facing the camera, but I can't figure out how to constrain their orientation such that they only rotate on the Z-axis. Otherwise it keeps the full face perpendicular to the camera and pulls the trees out of the ground.

Anyone have any ideas? I'm in max 4.2 if it makes a difference. Thanks!

Shaun

mbr · February 20th, 2004

I am not 100% clear as to what you are trying to do.

RPCs are made to look 'full' from all directions, not just the two planes that are represented in the viewport. This would mean that they will always look 'full', no matter what the angle. That's the advantage of RPCs.

If you are trying to keep them on the ground, well, that's another issue. There are plugins that will allow you to 'drop' objects onto a surface, like trees and fences.

ShaunDon · February 20th, 2004

Sorry about that. What I'm doing is populating the middleground of an animation with RPC trees -- outside the loop of the camera path, but ahead of the tree wall.

Problem is I have over 200 of them, and it takes a while to load all the RPCs even when culled down to simple billboards. I'm trying to save time and only using full RPCs in the building's landscaping. So I've made a plane and applied an RPC texture (just a TIF I made in Photoshop from the RPC file) and I just want to constrain that plane so that it always faces the camera. I don't care that I'm only using one image for the tree because these are peripheral background fillers, no one's going to notice that they're not rotating.

But the lookat constraint by default wants to make the entire face of the simplified RPC tree look at the camera, rather than just rotate it on the Z. I've only done this sort of thing in Maya while I was in school, I don't really know how to get it to work in Max.

Thanks guys.

Shaun

GI Dude · February 20th, 2004

Try this:

Use instances, for each type of tree, each rpc object uses about 4 mb of ram at the time of the rendering (i found about it in a support forum at discreet) if it doesn't work, you can use image trees instead, there's a plug for 3ds max/viz named forrest pack, and it works fine...

http://www.itoosoft.com/

I hope this can help you

Quique · February 20th, 2004

I had the same problem a while back.

I made a dummy object and with expressions made the Xposition of the dummy object equal the Xposition of the camera, same for the Yposition, but left the Z value 'height' alone. Instead of having the trees (planes) look at the camera, have them look at this dummy object. Move the dummy object accordingly in height so that the trees aren't looking down or up.

I hope this helps.

ShaunDon · February 20th, 2004

Yeah! We were trying to figure out how to constrain a dummy only to the XY coordinates of the camera... that's perfect. I'll give that a shot. Thanks!

Shaun

February 20th, 2004	#1 (permalink)
ShaunDon Senior Member Join Date: Jul 2003 Location: Portsmouth, NH Age: 26 Posts: 360 Name: Shaun Donnelly	Hey guys -- I've got a quick question... I'm trying to simplify some RPCs into planes with a LookAt constraint to keep them facing the camera, but I can't figure out how to constrain their orientation such that they only rotate on the Z-axis. Otherwise it keeps the full face perpendicular to the camera and pulls the trees out of the ground. Anyone have any ideas? I'm in max 4.2 if it makes a difference. Thanks! Shaun __________________ Shaun Donnelly TANGRAM 3DS

February 20th, 2004	#3 (permalink)
ShaunDon Senior Member Join Date: Jul 2003 Location: Portsmouth, NH Age: 26 Posts: 360 Name: Shaun Donnelly	Sorry about that. What I'm doing is populating the middleground of an animation with RPC trees -- outside the loop of the camera path, but ahead of the tree wall. Problem is I have over 200 of them, and it takes a while to load all the RPCs even when culled down to simple billboards. I'm trying to save time and only using full RPCs in the building's landscaping. So I've made a plane and applied an RPC texture (just a TIF I made in Photoshop from the RPC file) and I just want to constrain that plane so that it always faces the camera. I don't care that I'm only using one image for the tree because these are peripheral background fillers, no one's going to notice that they're not rotating. But the lookat constraint by default wants to make the entire face of the simplified RPC tree look at the camera, rather than just rotate it on the Z. I've only done this sort of thing in Maya while I was in school, I don't really know how to get it to work in Max. Thanks guys. Shaun __________________ Shaun Donnelly TANGRAM 3DS

February 20th, 2004	#4 (permalink)
GI Dude Senior Member Join Date: Feb 2004 Location: Monterrey Age: 31 Posts: 267 Name: Alex Guzman	Try this: Use instances, for each type of tree, each rpc object uses about 4 mb of ram at the time of the rendering (i found about it in a support forum at discreet) if it doesn't work, you can use image trees instead, there's a plug for 3ds max/viz named forrest pack, and it works fine... http://www.itoosoft.com/ I hope this can help you __________________ Alex Guzman

February 20th, 2004	#6 (permalink)
ShaunDon Senior Member Join Date: Jul 2003 Location: Portsmouth, NH Age: 26 Posts: 360 Name: Shaun Donnelly	Yeah! We were trying to figure out how to constrain a dummy only to the XY coordinates of the camera... that's perfect. I'll give that a shot. Thanks! Shaun __________________ Shaun Donnelly TANGRAM 3DS

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February 20th, 2004	#2 (permalink)
mbr Veteran Member Join Date: Aug 2002 Location: Los Angeles and Connecticut....and Denver Posts: 1,266 Name: Markus Byron	I am not 100% clear as to what you are trying to do. RPCs are made to look 'full' from all directions, not just the two planes that are represented in the viewport. This would mean that they will always look 'full', no matter what the angle. That's the advantage of RPCs. If you are trying to keep them on the ground, well, that's another issue. There are plugins that will allow you to 'drop' objects onto a surface, like trees and fences.

February 20th, 2004	#5 (permalink)
Quique Member Join Date: Nov 2002 Location: TX, USA Posts: 42 Name: Enrique Camacho	I had the same problem a while back. I made a dummy object and with expressions made the Xposition of the dummy object equal the Xposition of the camera, same for the Yposition, but left the Z value 'height' alone. Instead of having the trees (planes) look at the camera, have them look at this dummy object. Move the dummy object accordingly in height so that the trees aren't looking down or up. I hope this helps.

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