Irrlicht units in meters

RdR · Post by **RdR** » Mon Apr 25, 2011 1:54 pm

Hello,

I'm using Bullet (with irrBullet) and they suggest to use 1 unit = 1 meter for most realistic physics etc.
So I created all my models in Maya in meters, but when I load them in Irrlicht its in 100 times bigger (or just in centimeters).

What is the default units in Irrlicht?
How much is 1 unit in Irrlicht?
Should I scale all my models to 0.01 or is there a better solution?

How are you guys deciding what units to use?

Radikalizm · Post by **Radikalizm** » Mon Apr 25, 2011 2:01 pm

Irrlicht does not specify a set unit size, a unit can be anything you want it to be

The safest bet is to take 1 unit = 1 meter in irrlicht and scale the units used in the tools you're using accordingly, a 1 unit = 1 meter approach is also the safest option for avoiding floating point precision errors

I've never actually worked with Maya, but there should be an option to set up your world units

RdR · Post by **RdR** » Mon Apr 25, 2011 2:04 pm

Radikalizm wrote:Irrlicht does not specify a set unit size, a unit can be anything you want it to be

The safest bet is to take 1 unit = 1 meter in irrlicht and scale the units used in the tools you're using accordingly, a 1 unit = 1 meter approach is also the safest option for avoiding floating point precision errors

I've never actually worked with Maya, but there should be an option to set up your world units

Thanks for you reply, gonna search for that.

ChaiRuiPeng · Post by **ChaiRuiPeng** » Mon Apr 25, 2011 2:28 pm

you might need to set a scaling world constant when using bullet if your application is centered around irrlicht, in order to like before poster said avoid precision problems.

however my application is centered around bullet so i dont scale i just use small size on irrlicht. no problems detected so far.

TCM · Post by **TCM** » Tue Apr 26, 2011 8:08 am

Anybody knows the ratio recommended for Physx ?

RdR · Post by **RdR** » Tue Apr 26, 2011 5:47 pm

TCM wrote:Anybody knows the ratio recommended for Physx ?

http://gamedev.springnote.com/pages/2960186.xhtml

http://www.gamedev.net/topic/513434-phy ... p__4343002

TCM · Post by **TCM** » Tue Apr 26, 2011 6:20 pm

Thanks. Good reading material.

I am having problems with Physx. My simulation looks slow. Only if i set the time step to 1/20 it gets a bit more realistic. But of course setting the timestep to 1/20 is not fixing the cause, just the effect.

RdR · Post by **RdR** » Tue Apr 26, 2011 7:09 pm

TCM wrote:Thanks. Good reading material.

I am having problems with Physx. My simulation looks slow. Only if i set the time step to 1/20 it gets a bit more realistic. But of course setting the timestep to 1/20 is not fixing the cause, just the effect.

This is what Bullet suggest -> http://www.bulletphysics.org/mediawiki- ... _The_World