stencil shadow volumes
er... assume you have a model that casts a shadow. Now I need a shadow
volume of that thing. The easiest way I can think of is to simply
flatten the model perpendicular to the light direction, then run a
delaunay over the points to get a silhouette of that thing.
As you might expect, this is nothing for real time shadows.
The next method: extrude every triangle's edge and remove edges that
are twice in the list (front+back side are "glued together"). But I
fear problems I can't see so far.
Any idea how to (quickly) get the silhouette?
int main(int argc, ch...MntVerifyTimeout, (remote shadow member), clustering, volume shadowing
I've got a bizarre problem. Perhaps someone can point me in the right
Please don't reply via email (see below).
I have a three-node cluster. Node ELIJAH crashed (and for some reason
didn't reboot, even though the console parameters should be set so that
it reboots automatically). Nodes GLADIA and DANEEL remained up.
DISK$USER is a shadow set consisting of two SEAGATE SCSI-2 disks, one
member with a direct connection to ELIJAH and another with a direct
connection to DANEEL. This shadow set is mounted on all nodes during
startup. All disks are MSCP served to al...Stencilled Shadows
Based on this article
http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=27 I wonder if
it's possible to smooth the edges of the projected shadows, for exemple
make them blurry.
If you know another good paper about this, feel free to make me aware of
<email@example.com> a �crit dans le message de
> Hi !
> Based on this article
> http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=27 I wonder if
> it's possible to smooth the edges of the projected shadows, for exempl...Stencil Shadow
Can i write fast animation with stencil shadows, or there is some better/faste way
to make shadows?
> Can i write fast animation with stencil shadows, or there is some better/faste way
> to make shadows?
If you want sharp shadows, stencil shadows are probably the fastest.
Shadow maps require an additional texture, but easily expand to
> Can i write fast animation with stencil shadows
Yes, that's how Doom 3 does shadows...
/ O O \
\_____/ FTB. For email, remove my socks.
Governments, like diaper...Shadow volume
Hi! me again.
Thanks for all the info re: radiosity and forward and backward distributed
ray-tracing etc..., still getting my head round it though, as I'm not a
mathematician, and I've only been looking into it for the past weeks, so my
understanding is still very sketchy
anyway, how does shadow volume fit into all this. I read briefly about. I
believe it was introduced by Crow in 1977?
In fact, I'm slight confused. Can distributed ray-tracing be classed as a
form of radiosity?
In terms of view-dependency, I'm SURE I've read somewhere that radiosity is
a...artifacts during volume shadows
After the volume shadows algorithm, my program shows some cubes. Currently
there are some strange effects that I don't know how to delete:
-Shadows are totally black. I would like to have semi-trasparent shadows.
-Some strange figures appear at the end of the shadow volumes and look like
a projection of the cubes.
-Black lines connect the cubes to their projection. These are the borders of
the polygons of the shadows volumes.
While I'm sure that the first could be solved playing a little with alpha
settings, the last two artifacts are very strange. The base code I used was
the same of...Volume shadowing question
I have a two-node cluster with two shadowed volumes. Each volume has
one physical disk on each node. Like this
-- $100$dka100 = DSA1 = $101$dka400 --
-- $100$dka200 = DSA2 = $101$dka300 --
Now I've added a third node, node_c, that serves no disks. (It's not
strictly a satellite as it has its own system disk. I gave it 0 votes
anyhow. so that it could come and gor from the cluster without having to
Anyhow, the problem is that when I reboot the third node, one or both of
the shadow volumes will break ...Shadow volumes normals
I'm using the shadow volumes technique to produce shadows in my 3D scenes.
However, I have some problem with regards to the volume's normals
I tried several ways to compute them, none of them revealed themselves to be
successful. Let L be the light position and V0 and V1 two vertices of a
silhouette edge of the shadowing object. Here are some solutions I tried:
1. I first computed the normal like this: (V1-V0) x (L-V0). This gives a
good normal but with no garantee that it is oriented "outside" the volume.
2. To reorient the normal computed in (1), ...Shadow Volume Copy
We have a shadow logical disk, with two members.
They want to copy the physical files which form the shadow to another
I'm trying to create DCL with this commands
$ dismount lda1:
$! copy file
$ copy dkb0:vd1.dsk dkb1:[BACKUP]
$! Mount disk again
$ mou/sys/noassi dsa0: /shadow=($1$lda1:,$1$lda2:) shadowvol vds
$ dismount lda2:
$! copy file
$ copy dkb1:vd2.dsk dkb1:[BACKUP]
$! Mount disk again
$ mou/sys/noassi dsa0: /shadow=($1$lda1:,$1$lda2:) shadowvol vds
When I ran the commands manually one bye it w...Volume shadowing stalls...
Sometimes we get very very long merge operations that seem to take days even
though the system is quiet.... I think there is a back-off sensitivity to
systenm I/O that is perhaps getting triggered.... has anyone seen this sort
of thing ,. lots of memory and page resources of all sorts NPAGE and
PAGEDYN... 7.3-1 current patch
"Hal Kuff" <firstname.lastname@example.org> wrote in message news:<email@example.com>...
> Sometimes we get very very long merge operations that seem to take days even
> though the system is quiet.... I think there is a back-off sensitivity ...learning stencil shadows
I learn stencil shadows.
The result of tutorial that I saw, sucks...
It uses stencil buffer to return pure black color (no draw) for shadows.
I dont want my shadows to be black color!
I want to dark my shadowed regions of scene (I mean r/2 g/2 b/2 of original unshadowed rgb)
I think many methods to produce that result, but faster method I think requires to draw an alpha texture polygon on the whole scene.
What is the commonly used method from this?
If stencil is 2, 3, 4 or more, I want this region to be more darken than stencil = 1. How I can do this?
I can't help you directly with ...other shadow volume questions...
Now I have understand shadow volumes.
But I have some questions.
1. With which method can we determine which edges (between 2 neighbor polygons) must be extruded? I think a method: if 2 polygon
normals have different Z sign (+ / -) (first we transform the scene with the light in the origin). Is there a faster method?
2. What we can do I we are in the shadow? (Except to close our eyes!)
3. What we can do if one shadow volume polygon intersects near plane? We must use the Carmack's inverse?
4. Then what we can do if one shadow volume polygon intersects far plane? We must use the origina...volume shadowing over LAVC ?
is it possible to do volume shadowing over LAVC without HSx controler
(let say with local disk on each node) ?
> is it possible to do volume shadowing over LAVC without HSx controler
> (let say with local disk on each node) ?
Yes. Been there, done that on 10mbps ethernet back in 1992 at 5.5-2.
You need host based volume shadowing. The software is pretty smart and for
reads, if the local disk is already very busy, the reads are done on the
remote disk. So read throughput is actually increased. Writes are slower
because it waits for both disks to b...Volume Shadowing Availability
There was a document kicking around some 10 years ago that gave a
mathematical analysis of relative availability with single, two and
three member shadow sets. Guess it was about 15-20 pages long.
Anyone have an electronic copy or knwo where it was published?
Thanks and regards
Neil Lowden wrote:
> Hi Guys
> There was a document kicking around some 10 years ago that gave a
> mathematical analysis of relative availability with single, two and
> three member shadow sets. Guess it was about 15-20 pages long.
> Anyone have an electronic copy or knwo w...Help with stencil shadows?
I'm having a little trouble with stencil shadowing. Specifically my problem
is with self-shadowing.
I draw my object, then draw its shadow using the darkening method (copy
object geometry and add degenerate quads along edges, draw with two-sided
stencil, then draw an overlay poly to make the shadow). The problem is, the
frontcap of the shadow z-fights with the object itself, resulting in a
crawly, artifact-y self-shadow.
I've tried a couple of things, like playing with z-bias, 'jittering' the
shadow volume's verts in/out along their normals, etc, but nothing seems t...Stencil shadowing and transparent objects.
I've implemented stencil shadows for the better part, which is working
ok. But I'm wondering how to deal with transparent surfaces.
For example if you're looking through a fence on a racetrack; for nice
anti-aliasing you want to blend the fence, instead of doing an alpha
test hard cut.
That does mean though the Z-buffer won't get filled, but that
interferes with the operation of stencil shadows, since the shadow
volumes need to deal with Z-values to work.
Anybody know a way around this problem?
Ruud van Gaal
Free car sim: http://www.racer.nl/
Pencil art : http:...Re: Volume shadowing question
firstname.lastname@example.orgCLOTHESvax.de (Phillip Helbig---remove CLOTHES to reply)
wrote on 02/17/2004 03:13:15 PM:
> In article <Xns94928391CA344falkarcabca@126.96.36.199>, Alfred Falk
> <falk@arc.REMOVE.ab.ca> writes:
> > I have a two-node cluster with two shadowed volumes. Each volume has
> > one physical disk on each node. Like this
> > node_a:: node_b::
> > -- $100$dka100 = DSA1 = $101$dka400 --
> > -- $100$dka200 = DSA2 = $101$dka300 --
> > Now I've added a third node, node_c, that...Indexing shadow volumes with Spotlight
I found this tip http://www.dreness.com/blog/archives/16 on how to index
read-only volumes with Spotlight. The tip seems reasonable, (and very
useful) and correctly mounts the shadow volume, but for some reason I
get an error when the script tries to turn on the indexing for the
Does anybody have any ideas?
The script is below:
# pass in the name of the r/o volume, e.g. DiskWarriorCD
# this is proof of concept only. seriously :)
if [ ! $1 ] ; then echo "supply a volume name" ; exit 1 ; fi
rodevpath=`df | grep "$vol" ...Faster shadow volume rendering
I am receiving major slowdowns when rendering shadow volumes, (mostly
zfail, but it also occurs with zpass).
The processing algorithm I use is not the culprit as no matter how
slow it was to begin with or how fast it is optimised, the FPS can
still drop from above 80 to 10 and below (simply by panning the camera
down such that more of the volume would be visible).
I am using an infinite frustum, and am making proper use of the
homogenous coord in the volume vertices.
As it stands, my rendering is as follows, for each mesh in respect to
-Set perspective correction, point smoothi...volume shadowing question #2
We are installing an EVA4000 in replacement of an MSA1000.
I was wondering if I could use HBVS to switch my data onto the new storage,
That is: create a new drive on the EVA4000, mount it as a shadow member of
the existing one on MSA1000.
When the merge is complete, dismount the member that's on the MSA1000.
A possible technical problem:
The VMScluster is comprised of 2 Alphaservers and one IA64 server. When I
mount /cluster the shadow member, will all nodes see it properly (different
architecture should not be a problem on VMS) ?
And is there something obvious that ...tricky shadow volume problem
I have a program that uses the stencil incr decr method for making
shadows. This is the situation. Think of a mast on a ship that is
attached to the middle botom of the ship and assume that mast will
cast a shadow. The inside hull and the outside hull of the boat are
separate objects, one faces in and the other faces out.
Here is what is happening. The mast casts its shadow correctly on the
inside hull, but mysteriously, the shadow also appears on the outside
hull. I have tried to thinik through the way the front and back shadow
planes are drawn and I can see where this would happen. Sinc...DVE and DDS (volume shadowing)
I've read the help and the documentation but want to make sure I am not
missing anything. I have some shadow sets which I want to transfer to
larger disks. Of course, I could do an image backup, but I want to
avoid the problems with that (mainly time during which the source is not
usable since it needs to be write-locked).
I want to do this under 7.3-2; an upgrade to 8.3 will be done soon, but
for various reasons I want to reconfigure my hardware first.
Suppose I have a shadow set consisting of two small disk and want to
transfer it to two (or, later, perhaps more) larger disks. Is...Volume GUID vs Volume ID to Identify Volume
I am modifying directory read code of mine to take mount points,
directory junctions, and directory symbolic links into account. The
main point being to identify if one of the above has already been
I have used an array of GUIDs for quite some time to determine if a
mount point was previously traversed. Now I need to handle the
My current method is to use a file ID structure which contains the
volume ID and the file ID. But volume IDs may be identical if, for
example, the link points to a volume that was cloned from the current...volume sets and shadow sets
In the old days, members of a shadow set had to have the same geometry.
(Even longer ago, maybe there were even more restrictions.) Then it was
enough if the sizes (total blocks) were the same, and now one can even
have disks of different sizes.
Presumably a volume set (which of course can consists of shadow sets)
can never be a member of a shadow set. In other words, the only way to
move from a volume set to a "single logical disk" (i.e. not a volume
set) is via an offline backup.
Is there any chance that a volume set might, in the future, be supported
as a me...