[ODE] GIMPACT with doubles

gero.mueller@cloo.de gero.mueller at cloo.de
Thu Nov 2 09:02:10 MST 2006

I agree that trimeshed don't always need to be doubles, BUT the quats  
and vectors in the physics engine may  very well be doubles. How many  
are there? I have about 100 Objects, with (wildly guessing) 30  
floats/doubles, makes 3000 doubles/float. so if its 50k or 100k memory  
is no real difference, is it?
And for the runtime, i guess with doubles you have less error, so you  
need less "fixing" of any kind, less code to execute. So, i suggest  
that the trimesh collision and the ode physics can use both, float or  
double, and that one can chose for each package seperatly.
For my space game i use doubles for ODE and OPCODE, and it is not the  
bottleneck ;-)


Jason Perkins <starkos at gmail.com> schrieb:

> On 11/2/06, Martijn Buijs <buijs512 at planet.nl> wrote:
>> Some time ago someone mentioned the way OpenGL does that. E.g. glTranslatef
>> vs. glTranslated.
> I think that might have been my idea; regardless I remember the
> discussion. I guess I don't see why you would /ever/ need doubles for
> object-relative coordinates like box side lengths or a cylinder
> radius. How much does double-precision really buy you in the
> quaternions and  rotation matrices? It seems like there might be a
> possibility to reduce the memory bandwidth of the double-precision
> build by identifying the places where the extra precision is actually
> useful.
> If there are no significant drawbacks, I'll drop it on the feature
> request list and look at it...eventually.
> Jason
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