Stair climbing in collision tutorial vs Irrlicht tech demo

netkoji · Post by **netkoji** » Sun Feb 01, 2009 1:44 pm

Hello everyone, I am a quite recent user of Irrlicht still discovering its potential =)

I am currently try to understand why stair climbing in collision detection tutorial is buggy (ie. you get stuck on stairs at random moments when going up) while I'm not able to reproduce the same problem in the Irrlicht tech demo.

Is it using some other technique? Or maybe there's a method that easily fixes it?

Thanks!

rogerborg · Post by **rogerborg** » Sun Feb 01, 2009 8:55 pm

It's an artifact of the ellipse/triangle checks used in the collision animator. It's not meant to be production quality, just a quick and dirty tool for simulating a basic physical presence. As always, investigation and better solutions would be very welcome.

netkoji · Post by **netkoji** » Sun Feb 01, 2009 9:21 pm

So does the tech demo use some different form of a collision response? No matter how hard I try I can't seem to get stuck when climbing the stairs there, so I'm guessing it uses a less flawed technique.

Can anyone from the Irrlicht team shed more light on this?

BlindSide · Post by **BlindSide** » Sun Feb 01, 2009 10:08 pm

The demo source is available under Examples/Demo. Knock yourself out.

rogerborg · Post by **rogerborg** » Sun Feb 01, 2009 10:45 pm

Demo.cpp creates a slightly thinner ellipse: (25,50,25) vs (30,50,30) in example 07.

It's just maths, it's not that the animator bears you any personal grudge.

skumar · Post by **skumar** » Mon Feb 02, 2009 6:27 am

Another main point is the MESH ...

Make sure there are no problems with your mesh...

i dont know the exact reason but i also met this 'stuck' due to bad modelling of a level....

so just try different meshes tooo

netkoji · Post by **netkoji** » Mon Feb 02, 2009 8:35 pm

BlindSide wrote:The demo source is available under Examples/Demo. Knock yourself out.

doh... I obviously neglected to check in the Examples. Thanks for pointing it out.

rogerborg wrote:Demo.cpp creates a slightly thinner ellipse: (25,50,25) vs (30,50,30) in example 07.

I actually tried different sizes of an ellipse, but it didn't seem to help too much.

skumar wrote:Another main point is the MESH ...

Make sure there are no problems with your mesh...

i dont know the exact reason but i also met this 'stuck' due to bad modelling of a level....

What do you mean by a "mesh problem"?

skumar · Post by **skumar** » Tue Feb 03, 2009 3:41 am

I was not able to correctly figure out the problems that can interfere with the collision on the mesh. Some times in 3dsmax when we do edit poly modelling one or two polygons may have a slightly altered normal. In such cases i have seen that the collison get stuck there....

Make a level with simple flat floor and a very slowly ascending stairs and test...