floating point problems?

[Gernot Frisch]

Re: floating point problems?

[color=blue][color=green]
>> OK. If the center of scale is not identical for all points,
>> then thats the best solution.[/color]
>
> Center of scale ? You mean the origin of the coordinate system,
> right ? The origin has no relation to the normal vectors, because
> the do not change under translation. The problem I believe is that
> if you scale normal vectors, you enable Normalization, which is
> expensive.[/color]

Nah. Thin of a donut. When you scale it, the inner rings will go
further from the center, right? Now scale each vertex point along it's
normal direction. You get a blown-up donut this way.

[Karl Heinz Buchegger]

Re: floating point problems?

Arijit wrote:[color=blue]
>
> Karl Heinz Buchegger wrote:[color=green]
> > Gernot Frisch wrote:
> >[color=darkred]
> >>> glScalef( scale, scale, scale );
> >>>
> >>>>Does the very same as your mumbo jumbo 2 loop solution.
> >>
> >>Unfortunate ly not, I've got to scale the vetices along their normal
> >>directions, which makes this a bit expensive. I've decided to
> >>implement a temp-buffer for each object now, thank you.[/color]
> >
> >
> > OK. If the center of scale is not identical for all points,
> > then thats the best solution.[/color]
>
> Center of scale ? You mean the origin of the coordinate system, right ?[/color]

No. I mean 'center of scale'. The point that should be invariant under
the scale operation.
[color=blue]
> The origin has no relation to the normal vectors, because the do not
> change under translation. The problem I believe is that if you scale
> normal vectors, you enable Normalization, which is expensive.[/color]

I don't think that the OP has that problem.

--
Karl Heinz Buchegger
kbuchegg@gascad .at

[Karl Heinz Buchegger]

Re: floating point problems?

Gernot Frisch wrote:[color=blue]
>[color=green][color=darkred]
> >> OK. If the center of scale is not identical for all points,
> >> then thats the best solution.[/color]
> >
> > Center of scale ? You mean the origin of the coordinate system,
> > right ? The origin has no relation to the normal vectors, because
> > the do not change under translation. The problem I believe is that
> > if you scale normal vectors, you enable Normalization, which is
> > expensive.[/color]
>
> Nah. Thin of a donut. When you scale it, the inner rings will go
> further from the center, right? Now scale each vertex point along it's
> normal direction. You get a blown-up donut this way.[/color]

I see. You are right. That cannot be done with a classical scale
operation. The classical scale operation assumes that the center
of scale is a single point, which it isn't in your case.


--
Karl Heinz Buchegger
kbuchegg@gascad .at