[Papervision3D] 3DMax axis vs. PV3D axis

[Carlos Ulloa]

Don't know why the other engines adopted this convention, but in our 
case we discussed it here in this mailing list and our conclusion was 
that it made sense from the Flash point of view of things. PV3D AS2 had 
the Y axis inverted as in Flash, but we thought that was a bit too much. 
In any case the ball is in Adobe's side, as they now have to set the 3D 
conventions they want to use for Astro's 2.0001D capabilities. To ensure 
compatibility I imagine we all will follow. Same thing applies for the 
matrix conventions, camera settings and so on.

C4


Rob Bateman wrote:
> Hey Harrie
>
> This seems to be a recurring problem in all 3d flash coordinate 
> systems at the moment, and i'm not entirely sure where it originated
>
> essentially the problem is this: most 3d modeling packages seems to 
> use a right-handed coordinate system. If your not sure what this 
> means, hold out your right hand with your index and middle fingers 
> splayed at right angles to each other. The index finger represents the 
> x-axis, the middle finger the y axis and the direction the thumb is 
> pointing (assuming your hand is shaped teh same as mine) represents 
> the z axis. Youcan also think of a right handed coordinate system as 
> having a z-component that travels into the screen as you look as it 
> (so higher values of z mean further away)
>
> The problem is that all 3d engines in flash currently use a left 
> handed coordinate system! I'm not sure why this is but i imagine it 
> was probably initiated by the first implementation of the 3d matrix 
> transformations... i'm looking at you Sandy... ;)
>
> essentially Sandy, Papervision and Away3d all have this left-handed 
> system, with the z-axis coming out of the screen. I've never known any 
> different progamming-wise, but i can understand how frustrating it can 
> be for 3d designers! Maybe we can have a switch to allow this to be 
> configured as either left or right handed in the future?
>
> Rob
>
>
>
> On Nov 17, 2007 10:13 PM, <harrie at sonicbliss.org 
> <mailto:harrie at sonicbliss.org>> wrote:
>
>     Hi,
>
>     Probably due to inexperience with both tools, but after searching the
>     mailinglist and googling, as well as trying out a lot I can't get my
>     head around the following. How do I work with the axis in PV3D being
>     different (default?) from those in 3Dmax.
>
>     (some ascii art below:)
>
>     PV3D:
>      Y  Z
>      | /
>      |/__X
>
>     3DMax:
>        Z  Y
>        | /
>     X__|/
>
>     The only way to get stuff working seems to mirror and rotate the
>     whole
>     scene before exporting it to Collada. Also I need to change this line
>     in the collada file: <up_axis>Z_UP</up_axis> to:
>     <up_axis>Y_UP</up_axis>, otherwise some of the objects in the collada
>     file get flipped around when rendered (not all!?).
>
>     Has anyone had this issue before and perhaps knows how to handle this?
>     i.e. something deadsimple like a setting in either PV3D or 3DMax or
>     export settings of Collada? We're working with 3DMax7.0 for exporting
>     Collada.
>
>     Reason is, the designers are making a room in 3DMax and some
>     animations (intro) in it we want to pre-render. After showing that in
>     Flash as a movie, I want to take over by loading the collada and then
>     using interaction to interact with objects in the room. Seems the best
>     way to be talking about the same x,y,z, values, otherwise I cannot get
>     the room to seamlessly link together. (Also trying to figure out the
>     camera position at the same time...)
>
>     Cheers,
>     Harrie van der Lubbe
>
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>
>
> -- 
> Rob Bateman
> Flash Development & Consultancy
>
> Work: 0207 4823328
> Mobile: 07714 329 073
>
> rob.bateman at gmail.com <mailto:rob.bateman at gmail.com>
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