[ODE] Huge world vs precision problems

[Deak Szabolcs]

Sorry to say that, but scaling wouldn't help. The derives from the 
relative range of elements in the world, 2500 km size versus e.g. 1 m 
triangle. This relationship won't be changed by scaling the whole thing, 
you could even make the visuals worse (by downscaling and then upscaling 
for the screen - division followed by multiplication tends to lose more 
precision in the computer world than multiplication followed by division).

What would help - as sy. mentioned - is relocating the origin of the 
world every now and then according to the player's current position, if 
that is feasible. You cannot change the internal precision of the video 
hardware, so you're stuck with floats in the graphics.

Szabolcs


Anders Olofsson wrote:

>I tried the double precision version of ode but the problem was still 
>there, so.. I just made a little graphic test (OpenGL), 2 rotating 
>triangles one at origin and one at the far edge of the world. Ofocuse the 
>one at the far edge wobbled, kind of obvious. Then I tried specify the 
>triangles using doubles, no difference, still wobbling!. Strange and 
>depressing. So the problem isn't just in ODE, duh.
>
>What about scaling everything down to the size wich can be "handled" by 
>floats?. Any other drawbacks than the agony? ;)
>
>Thanks everyone.
>
>_______________________________________________
>ODE mailing list
>ODE at q12.org
>http://q12.org/mailman/listinfo/ode
>
>.
>
>  
>