Attached Link: billboarding.py

Maybe someone could confirm the above behaviour and maybe understand why that happens ?
Thanks you

Getting a "403 Forbidden" when trying to download script.

I also have often problems with OSX compatibility... I found that Python on OSX is much more sensitive than on PC...

Also 403 forbidden for me :)

Sorry guys, now the link is fixed.

this bit  seems to be in twice - should not do any harm though

import poser
scene = poser.Scene()

Uh - notwithstanding the issue of it not working on OSX, I don't see how this works at all.

To calculate which way the billboard should face, you have to compute the vector from the billboard to the camera.

Consider a camera that is at 0,0,0.

Consider two billboards - one that is north of the camera (-z) and one that is south of the camera (+z). These two billboards must face in opposite directions. The northern one must face south, and the southern one must face north.

Further, consider the dolly camera. When it rotates, it doesn't move - it just points to a different place in the scene. A billboard that is always facing this camera should not rotate just because the camera has rotated. It should rotate when the camera moves.

Its not a very big deal, but that is one of the example scripts that is included with my Python for Poser Manual. I'm not suggesting that I have copyright on every code block under the sun, rather the manual and its examples is intended to help you write your own scripts. Duplication of standard routines is inevitable and to be expected. I would however prefer that the scripts not be redistributed cart blanch or as in this case with just my explanatory header removed.

Yes it does appear that I have "typo-ed" and included the import and scene lines twice.

Can not say at this point why its not working on a Mac other than to echo  semidieu's comment that Mac Python can by picky.

Sorry about that Phil: I just copied and pasted the billboard section from a longer python script I'm doing in a new file, forgetting to put your author header.
I reuploaded the file with the header included. If you wish the file to be removed, please tell me and I will do it...

Its OK, its not a big deal.

Quote - Uh - notwithstanding the issue of it not working on OSX, I don't see how this works at all.

To calculate which way the billboard should face, you have to compute the vector from the billboard to the camera.

Consider a camera that is at 0,0,0.

Consider two billboards - one that is north of the camera (-z) and one that is south of the camera (+z). These two billboards must face in opposite directions. The northern one must face south, and the southern one must face north.

Further, consider the dolly camera. When it rotates, it doesn't move - it just points to a different place in the scene. A billboard that is always facing this camera should not rotate just because the camera has rotated. It should rotate when the camera moves.

Hi BagginsBill, most examples I found about billboarding techniques in general, they take into account only camera rotations (checked also some opengl tutorials on gamedev.net).
Afterall, if you move away the quad in front of you, say to your right, before it disappear from sight, even if it's not billboarding you won't notice it.

I'm not at all tracking what you're saying.

All the discussions of the technique on gamedev speak of camera position relative to the billboard quad, not camera orientation.

Example: http://www.gamedev.net/community/forums/topic.asp?topic_id=411132

Specifically, a ring of billboards surrounding the camera would all be facing the camera, each with a different normal. In the algorithm you're using, they'd all be facing in the same direction, with the same normal.

Here's another one - uses camera position.

http://www.gamedev.net/community/forums/topic.asp?topic_id=452635

I see some people using the view plane, not the view position. This is equivalent to what you're doing. But they note that it's not the same, and comment that it is "good enough". Maybe it is for some things. If, however, you have a wide angle camera, I doubt it's good enough.

http://www.gamedev.net/community/forums/topic.asp?topic_id=583098

The OP says:

Quote - Thanks for the quick answer. I had to revert the order (first rotate, then translate) but now it works. I assume this method doesn't align the billboards towards the view point, but the view plane instead, though this shouldn't really be a problem for me: It looks good enough.

But then another poster points out the camera position formula.

This article explains the difference quite well, and illustrates what is wrong with ignoring the camera position:

http://www.flipcode.com/archives/Billboarding-Excerpt_From_iReal-Time_Renderingi_2E.shtml

About halfway down it explains the difference between viewplane aligned and view point aligned and why it matters. Perhaps it's OK for the scenario you plan to use, but the anal retentive in me would force me to do it right.

BagginsBill, I totally misunderstood your first point, now I see what you meant. Thanks for those links about billboarding, indeed they show in detail how to achieve that and explain the theory behind it.
I will try to build a billboarding routine following those, expect more disturbing question :-)