gdalgorithms-list

RE: [Algorithms] Ray-AABB intersection

[Zhang Z. S. <Zha...@ub...>]

There is an error in the book. But the source i downloaded from the Internet
seems right.

	/* Check final candidate actually inside box */
	if (maxT[whichPlane] < 0.) return (FALSE);
	for (i = 0; i < NUMDIM; i++)
		if (whichPlane != i) {
			coord[i] = origin[i] + maxT[whichPlane] *dir[i];
			if (coord[i] < minB[i] || coord[i] > maxB[i])
				return (FALSE);
		} else {
			coord[i] = candidatePlane[i];
		}
	return (TRUE);				/* ray hits box */

-----Original Message-----
From: Pierre Terdiman [mailto:p.t...@wa...]
Sent: Thursday, August 10, 2000 12:03 PM
To: gda...@li...
Subject: [Algorithms] Ray-AABB intersection


Is there any known problem with Andrew Woo's Ray-AABB intersection code? (in
Graphic Gems I). It seems to miss some intersections... (?)


_______________________________________________
GDAlgorithms-list mailing list
GDA...@li...
http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list

Re: [Algorithms] Ray-AABB intersection

[<Chr...@Pl...>]

Pierre, do you need the intersection point to be calculated or
are you merely interested in the boolean hit/miss result?

If the latter, you can use a separating axis approach, which
is quite cheap (relatively).

For a description (with pseudo code), see the paper:

Arthur Gregory, Ming C. Lin, Stefan Gottschalk, Russell Taylor
"A Framework for Fast and Accurate Collision Detection for
Haptic Interaction"


Christer Ericson
SCEA, Santa Monica





"Pierre Terdiman" <p.t...@wa...>@lists.sourceforge.net on 08/10/2000
02:51:59 PM

Please respond to gda...@li...

Sent by:  gda...@li...


To:   <gda...@li...>
cc:
Subject:  Re: [Algorithms] Ray-AABB intersection


Weird. Looks like mine, but it still doesn't work well.

......ok once again I think I'd better rederive everything from scratch and
write my own, yeepa.... (sigh)

----- Original Message -----
From: Zhang Zhong Shan <Zha...@ub...>
To: <gda...@li...>
Sent: Thursday, August 10, 2000 8:36 AM
Subject: RE: [Algorithms] Ray-AABB intersection


> There is an error in the book. But the source i downloaded from the
Internet
> seems right.
>
> /* Check final candidate actually inside box */
> if (maxT[whichPlane] < 0.) return (FALSE);
> for (i = 0; i < NUMDIM; i++)
> if (whichPlane != i) {
> coord[i] = origin[i] + maxT[whichPlane] *dir[i];
> if (coord[i] < minB[i] || coord[i] > maxB[i])
> return (FALSE);
> } else {
> coord[i] = candidatePlane[i];
> }
> return (TRUE); /* ray hits box */
>
> -----Original Message-----
> From: Pierre Terdiman [mailto:p.t...@wa...]
> Sent: Thursday, August 10, 2000 12:03 PM
> To: gda...@li...
> Subject: [Algorithms] Ray-AABB intersection
>
>
> Is there any known problem with Andrew Woo's Ray-AABB intersection code?
(in
> Graphic Gems I). It seems to miss some intersections... (?)
>
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list


_______________________________________________
GDAlgorithms-list mailing list
GDA...@li...
http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list

Re: [Algorithms] Ray-AABB intersection

[Pierre T. <p.t...@wa...>]

Thanks! I'll have a look - I don't need the intersection point indeed.

Anyway I found why Woo's code wasn't working - it was a bug, but in my code.
Ok, thanks guys.

----- Original Message -----
From: <Chr...@Pl...>
To: <gda...@li...>
Sent: Friday, August 11, 2000 1:58 AM
Subject: Re: [Algorithms] Ray-AABB intersection


>
>
>
>
> Pierre, do you need the intersection point to be calculated or
> are you merely interested in the boolean hit/miss result?
>
> If the latter, you can use a separating axis approach, which
> is quite cheap (relatively).
>
> For a description (with pseudo code), see the paper:
>
> Arthur Gregory, Ming C. Lin, Stefan Gottschalk, Russell Taylor
> "A Framework for Fast and Accurate Collision Detection for
> Haptic Interaction"
>
>
> Christer Ericson
> SCEA, Santa Monica
>
>
>
>
>
> "Pierre Terdiman" <p.t...@wa...>@lists.sourceforge.net on
08/10/2000
> 02:51:59 PM
>
> Please respond to gda...@li...
>
> Sent by:  gda...@li...
>
>
> To:   <gda...@li...>
> cc:
> Subject:  Re: [Algorithms] Ray-AABB intersection
>
>
> Weird. Looks like mine, but it still doesn't work well.
>
> ......ok once again I think I'd better rederive everything from scratch
and
> write my own, yeepa.... (sigh)
>
> ----- Original Message -----
> From: Zhang Zhong Shan <Zha...@ub...>
> To: <gda...@li...>
> Sent: Thursday, August 10, 2000 8:36 AM
> Subject: RE: [Algorithms] Ray-AABB intersection
>
>
> > There is an error in the book. But the source i downloaded from the
> Internet
> > seems right.
> >
> > /* Check final candidate actually inside box */
> > if (maxT[whichPlane] < 0.) return (FALSE);
> > for (i = 0; i < NUMDIM; i++)
> > if (whichPlane != i) {
> > coord[i] = origin[i] + maxT[whichPlane] *dir[i];
> > if (coord[i] < minB[i] || coord[i] > maxB[i])
> > return (FALSE);
> > } else {
> > coord[i] = candidatePlane[i];
> > }
> > return (TRUE); /* ray hits box */
> >
> > -----Original Message-----
> > From: Pierre Terdiman [mailto:p.t...@wa...]
> > Sent: Thursday, August 10, 2000 12:03 PM
> > To: gda...@li...
> > Subject: [Algorithms] Ray-AABB intersection
> >
> >
> > Is there any known problem with Andrew Woo's Ray-AABB intersection code?
> (in
> > Graphic Gems I). It seems to miss some intersections... (?)
> >
> >
> > _______________________________________________
> > GDAlgorithms-list mailing list
> > GDA...@li...
> > http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list
> >
> > _______________________________________________
> > GDAlgorithms-list mailing list
> > GDA...@li...
> > http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list
>
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list
>
>
>
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list

Re: [Algorithms] Ray-AABB intersection

[Pierre T. <p.t...@wa...>]

Weird. Looks like mine, but it still doesn't work well.

......ok once again I think I'd better rederive everything from scratch and
write my own, yeepa.... (sigh)

----- Original Message -----
From: Zhang Zhong Shan <Zha...@ub...>
To: <gda...@li...>
Sent: Thursday, August 10, 2000 8:36 AM
Subject: RE: [Algorithms] Ray-AABB intersection


> There is an error in the book. But the source i downloaded from the
Internet
> seems right.
>
> /* Check final candidate actually inside box */
> if (maxT[whichPlane] < 0.) return (FALSE);
> for (i = 0; i < NUMDIM; i++)
> if (whichPlane != i) {
> coord[i] = origin[i] + maxT[whichPlane] *dir[i];
> if (coord[i] < minB[i] || coord[i] > maxB[i])
> return (FALSE);
> } else {
> coord[i] = candidatePlane[i];
> }
> return (TRUE); /* ray hits box */
>
> -----Original Message-----
> From: Pierre Terdiman [mailto:p.t...@wa...]
> Sent: Thursday, August 10, 2000 12:03 PM
> To: gda...@li...
> Subject: [Algorithms] Ray-AABB intersection
>
>
> Is there any known problem with Andrew Woo's Ray-AABB intersection code?
(in
> Graphic Gems I). It seems to miss some intersections... (?)
>
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list
>
> _______________________________________________
> GDAlgorithms-list mailing list
> GDA...@li...
> http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list

[Algorithms] confused

[Akbar A. <sye...@ea...>]

hey,
okay, i have not given this question my 48 hour lookup, review time.. but...

in watt and watt "advanced animation and rendering techniques"

page 70
"The net of control points forms a polyhedron in Cartesian space and the
position of the points in this space controls the shape of the surface"

note: "this space" -exclusive...

page 72
"Deformation of a parametric surface is achieved by moving the control
points that define it"
?
shouldn't it say something like...

sorry for the brief message, i hope you understand what i mean :)
but i have to get back to reading this :D
it's 4:43 am and i am on a role :D

peace.
akbar A.