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Subject: 
Re: LPub Rotation Step angle woes
Newsgroups: 
lugnet.cad.dev.mac
Date: 
Thu, 6 Nov 2008 17:40:57 GMT
Viewed: 
12286 times
  
In lugnet.cad.dev.mac, Allen Smith wrote:
   In lugnet.cad.dev.mac, Jim DeVona wrote:
   In lugnet.cad.dev.mac, Allen Smith wrote:
   I’m working on rotation steps, and I’m not seeing LPub do what I expect it to do.

I have the following file:

1   2 0 0 0 1 0 0 0 1 0 0 0 1 3865.dat
0 ROTSTEP 0 0 0 ABS
1   4 -150 -24 70 1 0 0 0 1 0 0 0 1 3005.dat
0 ROTSTEP 0 0 0 REL

Please note that instead of “0 ROTSTEP 0 0 0 REL”, the preferred meta command is “0 ROTSTEP END”.

  
  
  
That should give me:
  1. A step with a front view
  2. A step with the default 3D angle.

snip

  
   Am I completely missing something here? My output is not oriented the same way the pictures Jim posted in his tutorial were.

I am using LPub 4.0.0.1 with LDView 3.2.

Allen

Hi, Allen.

Here’s what I see when I open your example in LPub 4.0.0.1:



Alas. That is what I’m supposed to see, not what I actually do see. Something is convinced that the 0,0,0 rotation is actually equal to the default 3D angle, which causes requests for the real default 3D angle to be over-rotated.

There are 4 kinds of ROTSTEPS: REL, ABS, ADD, END

For REL, you add the angles from the ROTSTEP meta to the default viewing angle to get the final viewing angle. When you have a REL, ADD, or ABS rotation from previous steps, REL tosses out the affect of the previous ROTSTEPs.

0 0 0 REL # should not change the viewing angle

For ABS, you discard the default viewing angle and use the value provided in the meta as the final viewing angle. When you have REL, ADD or ABS rotation from the previous steps, ABS tosses out the affect of the previous ROTSTEPs.

0 0 0 ABS # forces and end on view of the model

For ADD, you add the values from the meta to the “current” viewing angle. This is like REL, but instead of adding the meta and the default view angle, you add the meta to the “current” viewing angle (as possibly defined by previous ROTSTEP metas). When you have REL, ADD, or ABS rotation from previous steps, ADD modifies the affect of those previous ROTSTEPs.

For END, the current view angle is defined as the default view angle.

  
  
I’m not sure why the difference, but I’ll list some possible factors.
  1. Side effects of other LPub options, e.g. to hide PLI

No.

  
  
  1. LDView version (I use a “4.0 Pre-Alpha” version from SourceForge/Travis)

No. LPub handles ROTSTEPs for the renderers.

  
  
  1. Assembly image cache - try clearing it (from the Tools menu) and clicking the Redraw button

Possibly. The most up to date caching mechanism takes rotation into account, so the unrotated version of the step would have a different name the the rotated name.

  
Well, it’s definitely not #1 or #3. Kevin or Travis, do you have any idea what is going on here?

I hope the above explanation helps.

Are you having trouble within BrickSmith, or using files created in BrickSmith with LPub?

If this is the second case, when I get back from my work trip, I’ll look into it.

  
  
A confession: I never use ROTSTEP ABS (I’m just in the habit of using REL), so I’m not very familiar with its behavior. I rotate things relative to the default view.

I probably misuse ROTSTEP, too (but I put it to good misuse). I usually put ROTSTEPs immediately after STEP commands (at the top of the file, for the first step) and before the parts I intend to rotate. So, my version of the file might look like this:

0 ROTSTEP 0 0 0 ABS
1   2 0 0 0 1 0 0 0 1 0 0 0 1 3865.dat
0 STEP
0 ROTSTEP 0 0 0 REL
1   4 -150 -24 70 1 0 0 0 1 0 0 0 1 3005.dat

Or, in the case of LPub multi steps, I put the ROTSTEP immediately after the multi step begin statement (which goes immediately after multi step end, which goes immediately after the STEP...).

Hopefully someone else can STEP in and clarify. I’m afraid I use a lot of voodoo to insert these commands.

Jim

As Kevin wrote, the form I posted is the correct one. This was a fairly recent epiphany on my part, which is why Bricksmith currently leads you astray in where it is putting step commands. 0 STEP/ROTSTEP is supposed to come after the parts in the step, not before. And ROTSTEP replaces STEP. I intend to fix this behavior in the next release of Bricksmith.

Allen

Please let me know if I can be more help.

Kevin



Message has 2 Replies:
  Re: LPub Rotation Step angle woes
 
(...) I know. I used the form I did to confirm that the default viewing angle was mathematically messed up (and for dramatic emphasis). (...) I've got them, now it's time to test them. (...) Yes, actually, it was LDView that was confused. Travis' (...) (16 years ago, 7-Nov-08, to lugnet.cad.dev.mac, FTX)
  Re: LPub Rotation Step angle woes
 
(...) Well, Allen said that the LDView 4 test build fixed the problem. At a guess, LPub using -cg on the command line (to set the camera angle to 0 so that all the rotation can be in the model itself?) and the QT version isn't handling that like it (...) (16 years ago, 7-Nov-08, to lugnet.cad.dev.mac, FTX)

Message is in Reply To:
  Re: LPub Rotation Step angle woes
 
(...) snip (...) Alas. That is what I'm supposed to see, not what I actually do see. Something is convinced that the 0,0,0 rotation is actually equal to the default 3D angle, which causes requests for the real default 3D angle to be over-rotated. (...) (16 years ago, 6-Nov-08, to lugnet.cad.dev.mac, FTX)

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