3D Space Limitations?

I read on another forum that DirectX has a fit sometimes if your models are not in a 4Kx4Kx4K area in 3D Space starting at 0,0,0 and not exceeding 4000,4000,4000...is this correct?

thx :)

No.

But floating point maths get less accurate the further you go from zero, so you should periodically normalise everything.

Sort of related; If I move my infinite 'sea' plane, continiously in one direction at a rate of say, 1 unit per pass, pretty soon my game becomes unstable and slow.

Wondering if this has anything to do with accuracy being out....or something else.

ok... yeah I think it makes it slower because of how blitz handles infinite planes, I am not an expert though.

I think if you reset the variable to zero ever time it reaches 1 or something like that, it would work or you could make an animated texture if you can't get that to work right

Yeah....I dont need to scroll the sea plane ....but did so to test something....and inturn, found this slow down. Additionally, when this occurs, and I let it go, after some time I see some artifacts on the display (some of my pixels get fixed and turn white - like dead pixels on a cam-corder) Memory bank illegal access? Odd.

Anyway, back to the topic; if floats are less accurate the further they are from zero (like 4K), then wouldnt a good test be something like...

Position cube1,0000,0000,0000
position cube2,4000,0000,0000

(main loop)

x#=x#+0.01

Moveentity cube1,x#,0,0
Moveentity cube1,x#,0,0

text 100,100,"Cube 1 X position: "+entityx(cube1,1)
text 100,130,"Cube 2 X position: "+entityx(cube2,1)

(repeat)

-----wouldnt the above return different (slightly) values (decimal)?

(Cant test the above here...just theory)

If you set up a test moving the camera and a cube away from the 0,0,0, you will see, as Gfk says, the world losing accuracy, as the cube and camera will jump around more and more. It's a sliding scale, so the further away you get, the worse everything is. Depends on what you set your camerarange at though, as this affect the z-buffer.

You could try and use the W-buffer, as i believe this is a linear scale.

>Additionally, when this occurs, and I let it go, after some time I see some
>artifacts on the display (some of my pixels get fixed and turn white - like
>dead pixels on a cam-corder) Memory bank illegal access? Odd.

Sounds like a dodgy graphics card... This is usually how memory problems manifest themselves.

Not a dodgy card. Perhaps more like a zbuffer oddity like Ross says.

Anyhow, as I said, I dont need to scroll my water plane so no dramas.

@ Thermo,

Post some example code if you think it's not your card. Never seen this before myself. If it's a z-buffer oddity then it should be an issue on all cards.

Let me sim it at home....if I can get it to happen again, All I can show is my movement code and a screen dump.