i am importing a collada document exported from 3d max.
the up-axis says z-up (<up_axis>Z_UP</up_axis>).
As far as i know, that means, that the coordinate system
the scene is stored in not the one opengl is using.
So i have to convert all the matrices that are stored in the
document like this:
<matrix>0 0 1 8.72369 1 0 0 8 0 1 0 7 0 0 0 1</matrix>

how do i do this? I would prefer a solution, where i just have to multiply
the incoming matrix with some kind of flipmatrix, but i am not sure if this is enough.
what would such a matrix look like?

if i convert the matrices i do also have to convert the vertices and the normals, right?

in which way do i have to convert those?

My goal is to have everything in the native OpenGL coordinate system.

I’ve read a suggestion, that not converting at all is preferred. But that would mean, that i have to alter every transformation for every different coordinate system and this is not an option.

It should be converting everything. If for some odd reason the <matrix> transform was overlooked then please file a bug in the sourceforge project’s bug tracker.

And, OpenGL has no default coordinate system. You can make a Z_UP application if you want. With coordinate systems, as long as all of your data is using the same one then it will look and work correctly. If you mix Z_UP and Y_UP systems you will see problems. Even though OpenGL has no default coordinate system I do understand that it is easier to just think of the world as Y_UP.

It does in case not convert the matricies. I filed a bug a few days ago at sf.net but it does not look like anybody’s looking at open bugs. at least not verry frequently ;o)

Importing it into what?
->Into an OpenGL application, but that does not realy matter. Read on…

That is the coordinate system orientation that 3ds Max uses.
->Right. Exported from max everything is fine. No complain here, just wanted to give you all the neccessary details.

This would depend on your application, not OpenGL.[/quote]
->Thats true, OpenGL is in fact coordinatesystem independent. But as far as i am concerned, i prefer using the OpenGL Coordinate System. What i do not want is to implement every transform for every possible Coordinate System.
Do you agree, that it seams to be wrong behavior, to just convert the geometry and not the Matrices?

When i am importing the converted (converted from Z_UP to Y_UP) collada file into max it looks as weird as in my application. I am using the max im/exporter from feeling software. Maybe this importer does nor hornor the axis tag.

COLLADA doesn’t offer arbitrary coordinate system orientation for this very reason. COLLADA offers only three right-handed orientations that are at right-angles to each other.

Both approaches are valid. Converting the geometry can be done simply by suffling the data around, without loosing precision that is important to many users. This is another reason COLLADA offers only three right-angle orientations. Performing mathmatical calculations can be a lot simpler to implement but on the other hand can loose precision.