[ODE] on changing the world-up vector

[Doron Tal]

A wish, to add to the wish list: not only allow allow the "world-up 
vector" 
to be the y- or z-axis, but allow the world-up vector to be *any* arbitrary
3D vector.   Either compile time or run time are fine with me.
The code would be cleaner if it referred to a variable corresponding
to the "world-up vector" rather than referring to some arbitrarily
chosen vector such as the Y-axis.

-DT



Matthew D. Hancher wrote:

>The thing that bugs me about dTerrain right now is the need for separate 
>Y-up an Z-up versions.  This also relates to the confusion over cylinder 
>orientation.  I have been meaning to propose the following: I think ODE 
>ought to have an option (compile-time, run-time, whatever) that specifies 
>whether objects with fundamental axes will be y-aligned or z-aligned.
>The terrain, cylinder, and capsule geoms would all behave accordingly, as 
>would any future objects that needed to arbitrarily select a preferred 
>axis.  (Are there any others already that I'm forgetting?)
>
>What do people think?  I'm not usually a big fan of options of this sort, 
>but this seems like a sufficiently religious debate that the best thing 
>to do is side-step it by passing the decision on to the user.
>
>At first I was attracted by the compile-time option, but adding those 
>results in exponential growth in the number of pre-compiled libraries 
>that it makes sense to maintain.  This would be easy and efficient to 
>implement with a few thunks at run-time, at the expense of a minor 
>increase in code size.  In fact, the collider look-up-table would 
>make this absolutely trivial for Geoms....
>  
>