z-fighting question

[Jan]

This is just out of curiosity.

I just realized, that z-fighting is often "animated" although the camera does not move a bit.
That means, that you can look at a wall and every frame other pixels "win" the fight.

I think that´s strange, because the input-data is bit by bit exactly the same. No vertices were changed, no modelview or projection matrix was touched, it´s all the same.
But still you can get this "animated" z-fighting.

Doesn´t that mean, that the hardware does not work correctly? Although this is of course a precision issue, the calculations should all yield to the same correct or wrong results, if the input data is the same, but nothing should change just out of fun.

Maybe someone knows more about that.

Bye,
Jan.

[DopeFish]

Personally Ive only ever seen z-fighting animate like that if one of the relevant inputs is changing.

If all inputs stay the same, z-fighting stays the same Ive seen.

[dorbie]

I agree, zfighting won't change unless the eye, objects or rendering order change. You may have something moving, even if the movement is so slight that you cannot see the difference.

[Jan]

Hm, have to check that, although i am quite sure nothing is moving.

[Omaha]

I'd have to agree with the "something is moving" suggestion...

But isn't it also possible that differing values could be getting generated if there is double buffering taking place?

[Hull]

What about writing a Z-Fighting Game :P ?