NORMALS

[STRAT]

hi Cesar

 

flipping or equalising normals from an autocad model into max is quite normal. not as normal as you discribing maybe but pretty normal all the same.

 

how are you modelling in ADT? the way you face up in acad also influences normals orientation.

[Cesar R]

hi , yes I model in ADT,

what do you mean by the way you face up ?

[STRAT]

i mean by the way you create ur surfaces. ie, rule surfing, edge surfing ect. the order you pick the boundaries when creating these surfaces has bearing on the normal face orientation.

 

how solids determin normals orientation i dont know.

[Ernest Burden III]

As a general rule, create points/vertices in a counter-clockwise order to have the normal face as the clock would.

 

i mean by the way you create ur surfaces. ie, rule surfing, edge surfing ect. the order you pick the boundaries when creating these surfaces has bearing on the normal face orientation.

You say you are trying to learn Lightscape by going into MAX? I have no idea about MAX, but LS has a function called 'focus points' by which you insert a (blank) block named either 'foc_out' or 'foc_in' and all geometry on the layer will be oriented by that block. These can be nested into other blocks, like a column, so one can make the column work perfectly and then make copies of it.

 

Also, MAX usually triangulates geometry, while LS prefers quads. The is a way in either the newest MAX or the next one to keep quads in MAX, but I don't recall the details.

 

My point is, if you want to learn LS, use LS and not MAX.

[Cesar R]

Hi guys, I am trying to learn LS so I modeled an small room with a door and a window, then I imported it into 3DSMAX, however a lot of the faces where inverted and I had to flip normals manualy. I exported from architectural desktop as a 3DS. is this suposed to happen? which means that if I model a house or a real scene I will have to spend hours fliping normal? help plz

[Jeff Mottle]

Yes for the most part when you model always create from left to right and in a counter clock wise direction and extrude in an upwards direction. This will ensure closed boxes face out and open plines face towards the user.

 

We have been doing a few experiments here becuase the two of us disagreed upon how AutoCAD treated creation direction and extrusion direction and we found some very intersting results.

 

1. Lines with a thickness will face the camera if they are a positive thickness and are drawn from left to right. Conversely that same line extruded in the positive direction but drawn from right to left will face away from the camera.

 

Now here is where things get weird. If you do the same using TABSURF regarless of the direction you choose to draw the line they will both face the camera. However if you draw an irregualar polygon it seems that the direction of the first two points will in most cases define the direcion of the normals for the entire pline. We have found a few exceptions and are baffled as to why it does not follow this rule.

 

BTW mirroring a non blocked faced objct will also flip the normals.

 

So yeah I'm sure I've thouroughly confused you now, but these are the rules that I have been following for over 6 years, but never spent the time to figure out why there were a few execptions. If anyone figures it out I'd love to know.

 

Also, MAX usually triangulates geometry, while LS prefers quads. The is a way in either the newest MAX or the next one to keep quads in MAX, but I don't recall the details.

Actually if you import atrue poly model from MAX 5 it still comes in a triangles. If you import it into ACAD you will see quads, but really the thrid edge is really just hidden. try setting SPLFRAME to 1 and you will see. I was quite dissapointed to find this out when I first dtarted testing the alpha for VIZ4

 

[ December 10, 2002, 02:25 PM: Message edited by: Jeff Mottle ]

[Cesar R]

thanks ill give that a try.

How can I make glass that looks like then render of the "bath" in LS? does it look good and realistic just because of what is reflecting?