RE: [GD-Consoles] transforms

[Mick W. <mi...@ne...>]

We use Matricies.  A matrix implicity contains the three heading vectors
(X,Y,Z = Right, Up, At unit vectors), we then have such amusing code as
(abridged):

 float dot_right_normal = Mth::DotProduct(mp_physics->m_matrix[X],normal);
 float angle = acosf(dot_right_normal);
 float turn_angle = angle * Script::GetFloat("Wall_Bounce_Angle_Multiplier")
* lerp;						// angle away from the wall
 mp_physics->m_matrix.RotateYLocal(turn_angle);		 // erm...

Hours of endless fun can be had with code such as this!

Angles are fine for 2d type problems.

Mick

-----Original Message-----
From: gam...@li...
[mailto:gam...@li...]On Behalf Of R
& D (GameBrains)
Sent: Thursday, May 09, 2002 4:49 PM
To: Tom Forsyth; Gam...@li...
Subject: Re: [GD-Consoles] transforms


Tom,
Thanks for your note.

> We store animations as either quaternions or as Euler angles as
appropriate,
> then convert them to matrices, and _then_ we do maths with them. Never
> attempt to do maths with angles - you'll just hurt yourself on those
> singularities. :-)
>

Excuse the follow-up question if it is naiive :-) but without the angles,
doesn't positioning code like physics become problematic?  It is easy to
look at a car bouncing off a guardrail and calculate a reflected angle and
new heading vector from an angle, but how would I go about doing that with
matrices only?

Thanks,
Brett


_______________________________________________________________

Have big pipes? SourceForge.net is looking for download mirrors. We supply
the hardware. You get the recognition. Email Us: ban...@so...
_______________________________________________
Gamedevlists-consoles mailing list
Gam...@li...
https://lists.sourceforge.net/lists/listinfo/gamedevlists-consoles
Archives:
http://sourceforge.net/mailarchive/forum.php?forum_idU3