Units of OBJ file

[anshul.bhardwaj]

Hey, i am trying bullet helloworld example using own rendering engine.
i am confusing about the units that should be taken from the maya obj file.
as we are using dynamicsWorld->setGravity(btVector3(0,-10,0)); that means the unit length is in meter.
maya cannot give obj file in meters. it always will be in centimeters.
will this affect physics?
if we have to draw a sphere of 1 unit length then what should be the unit of sphere in obj file?(is it 1 unit or 100 unit)?

[MaxDZ8]

will this affect physics?

Yes, see scaling the world. But it's probably more worthwhile scaling while importing instead, and use the typical setup. I cannot say anything more as I haven't used Maya in a while, but I'd just open a OBJ and check.

[anshul.bhardwaj]

Thanks for quick reply.
As given in your link , its said that Moving objects are assumed to be in the range of 0.05 units to 10 units in bullet 2.74.
is there any improved value for bullet 2.78 version?
And what about the size of the traingles in trianglemesh type collision data?

[MaxDZ8]

As given in your link , its said that Moving objects are assumed to be in the range of 0.05 units to 10 units in bullet 2.74.
is there any improved value for bullet 2.78 version?

Asked this myself some time ago. Apparently not. The limit on 5cm is fairly ok to me, it's not really limiting. Everything that is smaller is probably eligible to another kind of management such as non-gameplay-oriented particles. I haven't played with the upper bound yet but I expect 10m to be a fairly conservative measure.

And what about the size of the traingles in trianglemesh type collision data?

Sorry, cannot help you there. What's the deal with all those trimeshes around? Looks like everyone wants to use them!