## RE: [2] [Algorithms] Generating Shadow Volumes with open geometry

 RE: [2] [Algorithms] Generating Shadow Volumes with open geometry From: Emmanuel Astier - 2002-02-27 12:36:09 ```But that only works if the light+mesh move is small enougth. You can't insure every edge of the silhouette at trame t as a common triangle with a edge at trame t-1 ? And if you're using quad, it's very possible that the silhouette edge come from one of the quad edge to the quad opposite edge... * /* / * * * * * * * * * \ * \* * Here if the light moves ( in the quad world ) is orthogonal to the '*' edges, the silhouette will jump from the first * edge to the second... Am I completely wrong ??? Emmanuel > -----Original Message----- > From: Willem H. de Boer [mailto:Willem@...] > Sent: mercredi 27 f=E9vrier 2002 13:10 > To: Ulf Ochsenfahrt; GD-Algorithms List > Subject: RE: [2] [Algorithms] Generating Shadow Volumes with open > geometry >=20 >=20 > "start with the {edge list} of the=20 > last frame and if an edge of the last frame is not a silhouette=20 > edge in this frame, check the edges it connects to." >=20 > Oh, I think I should point out that with {edge list} I mean > the silhouette edge list, not the entire mesh's edge list >=20 > -----Original Message----- > From: Ulf Ochsenfahrt [mailto:ulfjack@...] > Sent: 27 February 2002 11:32 > To: GD-Algorithms List > Subject: RE:[2] [Algorithms] Generating Shadow Volumes with open > geometry >=20 >=20 > I think I'd do this differently. >=20 > What about this: > Put in a bit flag for each triangle which show which way the=20 > triangle is > facing. Whenever a triangle changes, you check the adjacent edges. > Some of the are then moved out of the silhouette edges list and some > are inserted. >=20 > This may be more accurate if you have concave objects. >=20 > -- Ulf. >=20 > "Willem H. de Boer" wrote on 27/02/02 10:31:22: > > > >Well, one way of going about speeding up edge detection, would > >be temporal coherence. So, calculate the silhouette edges for > >the shadow-casting object the expensive way (some winged edge > >structure, find the edges connecting a back-facing triangle > >with a front-facing one), and store it in a list. Then for the=20 > >next frame, or after T frames, start with the edge list of the=20 > >last frame and if an edge of the last frame is not a silhouette=20 > >edge in this frame, check the edges it connects to. This saves=20 > >a lot of edge tracking; more efficient with higher temporal=20 > coherence. > > > >Cheers, > > > >Willem > >MuckyFoot Goat Boy > > > >-----Original Message----- > >From: Chris Perry [mailto:perry@...] > >Sent: 27 February 2002 08:16 > >To: gdalgorithms-list@... > >Subject: RE: [Algorithms] Generating Shadow Volumes with=20 > open geometry > > > > > >if a triangle is facing the light, then you can safely=20 > extrude any edges > >that=20 > >either have no neighbor or have a neighbor that is not=20 > facing the light. > > > >It's funny, I'm actually working on shadow volumes right now=20 > and I was > >trying to think of a way to speed up the edge detection process. It > >wouldn't > >work on objects with holes, but if you knew you had a solid object > >you could theoretically trace one edge to the next until you came=20 > >full circle, right? -limiting the search space to only child edges. > >I've been wasting too much time trying to create a tree=20 > structure that > >links them together in a way which won't produce endless circles. I=20 > >think you have to treat the edges as symbolic vectors and keep=20 > >a "head" to "tail" orientation... i.e. an edge is a child if=20 > it's "tail" is > >the > >parent edge's "head"... hmmm...who knows, maybe it's impossible... > > > >-Chris Perry > >Angel Studios > > > > > > > >-----Original Message----- > >From: Jason Zisk [SMTP:ziskj@...] > >Sent: Tuesday, February 26, 2002 8:32 PM > >To: gdalgorithms-list@... > >Subject: [Algorithms] Generating Shadow Volumes with=20 > open geometry > > > >Quick question about shadow volumes. A lot of our geometry=20 > is "open", for > >instance a cylinder with no top or bottom. When generating=20 > a shadow volume > >for it, what do you do with the triangle edges that aren't=20 > shared between > >two triangles when it comes to checking if the edge is a=20 > silhouette? With > >two triangles you just see if one is facing the light and=20 > one isnt, then > >extrude that edge. With only one triangle, do you simply=20 > check if the > >triangle is back-facing, if so extrude? I'd like to hear=20 > what others do in > >this situation. > > > >Thanks, > > > > - Jason Zisk > >- nFusion Interactive LLC > > > > > > > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 >=20 >=20 > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 ```

 RE: [Algorithms] Generating Shadow Volumes with open geometry From: Chris Perry - 2002-02-27 08:16:20 ```if a triangle is facing the light, then you can safely extrude any edges that either have no neighbor or have a neighbor that is not facing the light. It's funny, I'm actually working on shadow volumes right now and I was trying to think of a way to speed up the edge detection process. It wouldn't work on objects with holes, but if you knew you had a solid object you could theoretically trace one edge to the next until you came full circle, right? -limiting the search space to only child edges. I've been wasting too much time trying to create a tree structure that links them together in a way which won't produce endless circles. I think you have to treat the edges as symbolic vectors and keep a "head" to "tail" orientation... i.e. an edge is a child if it's "tail" is the parent edge's "head"... hmmm...who knows, maybe it's impossible... -Chris Perry Angel Studios -----Original Message----- From: Jason Zisk [SMTP:ziskj@...] Sent: Tuesday, February 26, 2002 8:32 PM To: gdalgorithms-list@... Subject: [Algorithms] Generating Shadow Volumes with open geometry Quick question about shadow volumes. A lot of our geometry is "open", for instance a cylinder with no top or bottom. When generating a shadow volume for it, what do you do with the triangle edges that aren't shared between two triangles when it comes to checking if the edge is a silhouette? With two triangles you just see if one is facing the light and one isnt, then extrude that edge. With only one triangle, do you simply check if the triangle is back-facing, if so extrude? I'd like to hear what others do in this situation. Thanks, - Jason Zisk - nFusion Interactive LLC _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 ```
 RE: [Algorithms] Generating Shadow Volumes with open geometry From: Alex Clarke - 2002-02-27 09:11:10 ```Generally you need shadow volumes to be sealed, particularly if you are using the robust variant of stencil shadows (the one where you inc / dec the stencil value where the z-test fails). In Malice we tag surfaces as being display and or shadow. If an object casts shadows, the shadow surface must be properly sealed and manifold. There is no such requirement for display faces. Designing levels / art from scratch to be sealed is generally OK. However retrofitting objects to be sealed is really quite a chore. It might be possible to write a tool to auto seal an object, although that sounds like a hard thing to write. In the end you have to work out what's better: spending (perhaps a lot of) artist time on a solution that will work OR a potentially open ended research project that might save lots of artist time. Alex Clarke, Programmer (www.argonaut.com/malice.asp) Argonaut Games PLC > -----Original Message----- > From: Jason Zisk [mailto:ziskj@...] > Sent: 27 February 2002 04:32 > To: gdalgorithms-list@... > Subject: [Algorithms] Generating Shadow Volumes with open geometry > > > Quick question about shadow volumes. A lot of our geometry > is "open", for > instance a cylinder with no top or bottom. When generating a > shadow volume > for it, what do you do with the triangle edges that aren't > shared between > two triangles when it comes to checking if the edge is a > silhouette? With > two triangles you just see if one is facing the light and one > isnt, then > extrude that edge. With only one triangle, do you simply check if the > triangle is back-facing, if so extrude? I'd like to hear > what others do in > this situation. > > Thanks, > > - Jason Zisk > - nFusion Interactive LLC > > > > > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > ```
 RE: [Algorithms] Generating Shadow Volumes with open geometry From: Willem H. de Boer - 2002-02-27 09:32:32 ```Well, one way of going about speeding up edge detection, would be temporal coherence. So, calculate the silhouette edges for the shadow-casting object the expensive way (some winged edge structure, find the edges connecting a back-facing triangle with a front-facing one), and store it in a list. Then for the next frame, or after T frames, start with the edge list of the last frame and if an edge of the last frame is not a silhouette edge in this frame, check the edges it connects to. This saves a lot of edge tracking; more efficient with higher temporal coherence. Cheers, Willem MuckyFoot Goat Boy -----Original Message----- From: Chris Perry [mailto:perry@...] Sent: 27 February 2002 08:16 To: gdalgorithms-list@... Subject: RE: [Algorithms] Generating Shadow Volumes with open geometry if a triangle is facing the light, then you can safely extrude any edges that either have no neighbor or have a neighbor that is not facing the light. It's funny, I'm actually working on shadow volumes right now and I was trying to think of a way to speed up the edge detection process. It wouldn't work on objects with holes, but if you knew you had a solid object you could theoretically trace one edge to the next until you came full circle, right? -limiting the search space to only child edges. I've been wasting too much time trying to create a tree structure that links them together in a way which won't produce endless circles. I think you have to treat the edges as symbolic vectors and keep a "head" to "tail" orientation... i.e. an edge is a child if it's "tail" is the parent edge's "head"... hmmm...who knows, maybe it's impossible... -Chris Perry Angel Studios -----Original Message----- From: Jason Zisk [SMTP:ziskj@...] Sent: Tuesday, February 26, 2002 8:32 PM To: gdalgorithms-list@... Subject: [Algorithms] Generating Shadow Volumes with open geometry Quick question about shadow volumes. A lot of our geometry is "open", for instance a cylinder with no top or bottom. When generating a shadow volume for it, what do you do with the triangle edges that aren't shared between two triangles when it comes to checking if the edge is a silhouette? With two triangles you just see if one is facing the light and one isnt, then extrude that edge. With only one triangle, do you simply check if the triangle is back-facing, if so extrude? I'd like to hear what others do in this situation. Thanks, - Jason Zisk - nFusion Interactive LLC _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 ```
 RE: [Algorithms] Generating Shadow Volumes with open geometry From: phil_wilkins@Playstation.sony.com - 2002-02-27 17:45:06 ```> It might be possible to write a tool to auto seal an object, although that sounds like a hard thing to write. It is. I wrote one for Alien as part of my experiments in generating grown BSP trees from polygon soups. The source is probably on a server / backup over there, somewhere (EdgeModel.h & cpp ). However, my general conclusion was that it's easier to hilight errors in the model viewer, and get the artists to fix it. Cheers, Phil Alex Clarke Sent by: To: "'Jason Zisk'" , gdalgorithms-list-admin@... gdalgorithms-list@... eforge.net cc: Subject: RE: [Algorithms] Generating Shadow Volumes with open geometry 02/27/2002 01:08 AM Generally you need shadow volumes to be sealed, particularly if you are using the robust variant of stencil shadows (the one where you inc / dec the stencil value where the z-test fails). In Malice we tag surfaces as being display and or shadow. If an object casts shadows, the shadow surface must be properly sealed and manifold. There is no such requirement for display faces. Designing levels / art from scratch to be sealed is generally OK. However retrofitting objects to be sealed is really quite a chore. It might be possible to write a tool to auto seal an object, although that sounds like a hard thing to write. In the end you have to work out what's better: spending (perhaps a lot of) artist time on a solution that will work OR a potentially open ended research project that might save lots of artist time. Alex Clarke, Programmer (www.argonaut.com/malice.asp) Argonaut Games PLC > -----Original Message----- > From: Jason Zisk [mailto:ziskj@...] > Sent: 27 February 2002 04:32 > To: gdalgorithms-list@... > Subject: [Algorithms] Generating Shadow Volumes with open geometry > > > Quick question about shadow volumes. A lot of our geometry > is "open", for > instance a cylinder with no top or bottom. When generating a > shadow volume > for it, what do you do with the triangle edges that aren't > shared between > two triangles when it comes to checking if the edge is a > silhouette? With > two triangles you just see if one is facing the light and one > isnt, then > extrude that edge. With only one triangle, do you simply check if the > triangle is back-facing, if so extrude? I'd like to hear > what others do in > this situation. > > Thanks, > > - Jason Zisk > - nFusion Interactive LLC > > > > > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 ```
 RE: [2] [Algorithms] Generating Shadow Volumes with open geometry From: Emmanuel Astier - 2002-02-27 12:36:09 ```But that only works if the light+mesh move is small enougth. You can't insure every edge of the silhouette at trame t as a common triangle with a edge at trame t-1 ? And if you're using quad, it's very possible that the silhouette edge come from one of the quad edge to the quad opposite edge... * /* / * * * * * * * * * \ * \* * Here if the light moves ( in the quad world ) is orthogonal to the '*' edges, the silhouette will jump from the first * edge to the second... Am I completely wrong ??? Emmanuel > -----Original Message----- > From: Willem H. de Boer [mailto:Willem@...] > Sent: mercredi 27 f=E9vrier 2002 13:10 > To: Ulf Ochsenfahrt; GD-Algorithms List > Subject: RE: [2] [Algorithms] Generating Shadow Volumes with open > geometry >=20 >=20 > "start with the {edge list} of the=20 > last frame and if an edge of the last frame is not a silhouette=20 > edge in this frame, check the edges it connects to." >=20 > Oh, I think I should point out that with {edge list} I mean > the silhouette edge list, not the entire mesh's edge list >=20 > -----Original Message----- > From: Ulf Ochsenfahrt [mailto:ulfjack@...] > Sent: 27 February 2002 11:32 > To: GD-Algorithms List > Subject: RE:[2] [Algorithms] Generating Shadow Volumes with open > geometry >=20 >=20 > I think I'd do this differently. >=20 > What about this: > Put in a bit flag for each triangle which show which way the=20 > triangle is > facing. Whenever a triangle changes, you check the adjacent edges. > Some of the are then moved out of the silhouette edges list and some > are inserted. >=20 > This may be more accurate if you have concave objects. >=20 > -- Ulf. >=20 > "Willem H. de Boer" wrote on 27/02/02 10:31:22: > > > >Well, one way of going about speeding up edge detection, would > >be temporal coherence. So, calculate the silhouette edges for > >the shadow-casting object the expensive way (some winged edge > >structure, find the edges connecting a back-facing triangle > >with a front-facing one), and store it in a list. Then for the=20 > >next frame, or after T frames, start with the edge list of the=20 > >last frame and if an edge of the last frame is not a silhouette=20 > >edge in this frame, check the edges it connects to. This saves=20 > >a lot of edge tracking; more efficient with higher temporal=20 > coherence. > > > >Cheers, > > > >Willem > >MuckyFoot Goat Boy > > > >-----Original Message----- > >From: Chris Perry [mailto:perry@...] > >Sent: 27 February 2002 08:16 > >To: gdalgorithms-list@... > >Subject: RE: [Algorithms] Generating Shadow Volumes with=20 > open geometry > > > > > >if a triangle is facing the light, then you can safely=20 > extrude any edges > >that=20 > >either have no neighbor or have a neighbor that is not=20 > facing the light. > > > >It's funny, I'm actually working on shadow volumes right now=20 > and I was > >trying to think of a way to speed up the edge detection process. It > >wouldn't > >work on objects with holes, but if you knew you had a solid object > >you could theoretically trace one edge to the next until you came=20 > >full circle, right? -limiting the search space to only child edges. > >I've been wasting too much time trying to create a tree=20 > structure that > >links them together in a way which won't produce endless circles. I=20 > >think you have to treat the edges as symbolic vectors and keep=20 > >a "head" to "tail" orientation... i.e. an edge is a child if=20 > it's "tail" is > >the > >parent edge's "head"... hmmm...who knows, maybe it's impossible... > > > >-Chris Perry > >Angel Studios > > > > > > > >-----Original Message----- > >From: Jason Zisk [SMTP:ziskj@...] > >Sent: Tuesday, February 26, 2002 8:32 PM > >To: gdalgorithms-list@... > >Subject: [Algorithms] Generating Shadow Volumes with=20 > open geometry > > > >Quick question about shadow volumes. A lot of our geometry=20 > is "open", for > >instance a cylinder with no top or bottom. When generating=20 > a shadow volume > >for it, what do you do with the triangle edges that aren't=20 > shared between > >two triangles when it comes to checking if the edge is a=20 > silhouette? With > >two triangles you just see if one is facing the light and=20 > one isnt, then > >extrude that edge. With only one triangle, do you simply=20 > check if the > >triangle is back-facing, if so extrude? I'd like to hear=20 > what others do in > >this situation. > > > >Thanks, > > > > - Jason Zisk > >- nFusion Interactive LLC > > > > > > > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > > > >_______________________________________________ > >GDAlgorithms-list mailing list > >GDAlgorithms-list@... > >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > >Archives: > >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 >=20 >=20 > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >=20 ```
 RE: [Algorithms] Generating Shadow Volumes with open geometry From: phil_wilkins@Playstation.sony.com - 2002-02-27 17:49:56 ```Only if your solid is convex. Think of barbells, then donuts, then another aproach...;) Cheers, Phil Chris Perry Sent by: To: "gdalgorithms-list@..." gdalgorithms-list-admin@... eforge.net cc: Subject: RE: [Algorithms] Generating Shadow Volumes with open geometry 02/27/2002 12:16 AM Please respond to "perry@..." if a triangle is facing the light, then you can safely extrude any edges that either have no neighbor or have a neighbor that is not facing the light. It's funny, I'm actually working on shadow volumes right now and I was trying to think of a way to speed up the edge detection process. It wouldn't work on objects with holes, but if you knew you had a solid object you could theoretically trace one edge to the next until you came full circle, right? -limiting the search space to only child edges. I've been wasting too much time trying to create a tree structure that links them together in a way which won't produce endless circles. I think you have to treat the edges as symbolic vectors and keep a "head" to "tail" orientation... i.e. an edge is a child if it's "tail" is the parent edge's "head"... hmmm...who knows, maybe it's impossible... -Chris Perry Angel Studios -----Original Message----- From: Jason Zisk [SMTP:ziskj@...] Sent: Tuesday, February 26, 2002 8:32 PM To: gdalgorithms-list@... Subject: [Algorithms] Generating Shadow Volumes with open geometry Quick question about shadow volumes. A lot of our geometry is "open", for instance a cylinder with no top or bottom. When generating a shadow volume for it, what do you do with the triangle edges that aren't shared between two triangles when it comes to checking if the edge is a silhouette? With two triangles you just see if one is facing the light and one isnt, then extrude that edge. With only one triangle, do you simply check if the triangle is back-facing, if so extrude? I'd like to hear what others do in this situation. Thanks, - Jason Zisk - nFusion Interactive LLC _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 _______________________________________________ GDAlgorithms-list mailing list GDAlgorithms-list@... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 ```
 [Algorithms] midpoint displacement problems From: David Zaadstra - 2002-02-27 20:12:09 ```Hello everybody, I have a problem with the midpoint displacement algorithm (from GPG1). I get strange little peaks all around my landscape. I've been looking for the bug for hours now and starting to believe that I'm a complete idiot. Could it be that the peaks are normal? That would explain why an erosion filter was added to the example file in GPG... Please take a look at this screenshot to see what I mean: http://www.gameprogramming.de/screen.jpg (not a very good one, i know) Thanks for your help, David ```
 AW: [Algorithms] midpoint displacement problems From: Gottfried Chen - 2002-02-28 10:02:48 ```I've implemented the algorithm a while ago and had the exact same "error" you have. Actually it turned out not to be an error. Just play around a bit with the "number of iterations between smoothing filter" parameter a bit. Then it should look like this: http://www.unet.univie.ac.at/~a9104678/ChengineOrg/Images/Screenshots/Terrai nTexture.jpg gottfried > -----Ursprüngliche Nachricht----- > Von: gdalgorithms-list-admin@... > [mailto:gdalgorithms-list-admin@...]Im Auftrag von > David Zaadstra > Gesendet: Mittwoch, 27. Februar 2002 21:12 > An: gdalgorithms-list@... > Betreff: [Algorithms] midpoint displacement problems > > > Hello everybody, > > I have a problem with the midpoint displacement algorithm (from GPG1). > I get strange little peaks all around my landscape. I've been looking for > the bug for hours now and starting to believe that I'm a complete idiot. > Could it be that the peaks are normal? That would explain why an erosion > filter was added to the example file in GPG... > Please take a look at this screenshot to see what I mean: > http://www.gameprogramming.de/screen.jpg (not a very good one, i know) > > Thanks for your help, > David > > > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > ```
 AW: [Algorithms] midpoint displacement problems From: Gottfried Chen - 2002-02-28 11:15:56 ```oops, sorry, mixed this up with fault formation. actually you have to tweak the roughness and fir filter factors. (in the image i've used a roughness of 1 and a fir filter constant of 0.1f). > -----Ursprüngliche Nachricht----- > Von: gdalgorithms-list-admin@... > [mailto:gdalgorithms-list-admin@...]Im Auftrag von > Gottfried Chen > Gesendet: Donnerstag, 28. Februar 2002 11:02 > An: David Zaadstra; gdalgorithms-list@... > Betreff: AW: [Algorithms] midpoint displacement problems > > > I've implemented the algorithm a while ago and had the exact same "error" > you have. Actually it turned out not to be an error. Just play > around a bit > with the "number of iterations between smoothing filter" parameter a bit. > Then it should look like this: > http://www.unet.univie.ac.at/~a9104678/ChengineOrg/Images/Screensh ots/Terrai > nTexture.jpg > > gottfried > > > -----Ursprüngliche Nachricht----- > > Von: gdalgorithms-list-admin@... > > [mailto:gdalgorithms-list-admin@...]Im Auftrag von > > David Zaadstra > > Gesendet: Mittwoch, 27. Februar 2002 21:12 > > An: gdalgorithms-list@... > > Betreff: [Algorithms] midpoint displacement problems > > > > > > Hello everybody, > > > > I have a problem with the midpoint displacement algorithm (from GPG1). > > I get strange little peaks all around my landscape. I've been > looking for > > the bug for hours now and starting to believe that I'm a complete idiot. > > Could it be that the peaks are normal? That would explain why an erosion > > filter was added to the example file in GPG... > > Please take a look at this screenshot to see what I mean: > > http://www.gameprogramming.de/screen.jpg (not a very good one, i know) > > > > Thanks for your help, > > David > > > > > > _______________________________________________ > > GDAlgorithms-list mailing list > > GDAlgorithms-list@... > > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > > Archives: > > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > > > > > > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > ```
 Re: [Algorithms] midpoint displacement problems From: David Zaadstra - 2002-02-28 12:55:48 ```Sorry, but your landscape still looks wrong. The peaks are disturbing. Your texturing is good though ;-) ----- Original Message ----- From: "Gottfried Chen" To: "David Zaadstra" ; Sent: Thursday, February 28, 2002 12:14 PM Subject: AW: [Algorithms] midpoint displacement problems > oops, sorry, mixed this up with fault formation. actually you have to tweak > the roughness and fir filter factors. (in the image i've used a roughness of > 1 and a fir filter constant of 0.1f). > > > -----Ursprüngliche Nachricht----- > > Von: gdalgorithms-list-admin@... > > [mailto:gdalgorithms-list-admin@...]Im Auftrag von > > Gottfried Chen > > Gesendet: Donnerstag, 28. Februar 2002 11:02 > > An: David Zaadstra; gdalgorithms-list@... > > Betreff: AW: [Algorithms] midpoint displacement problems > > > > > > I've implemented the algorithm a while ago and had the exact same "error" > > you have. Actually it turned out not to be an error. Just play > > around a bit > > with the "number of iterations between smoothing filter" parameter a bit. > > Then it should look like this: > > http://www.unet.univie.ac.at/~a9104678/ChengineOrg/Images/Screensh > ots/Terrai > > nTexture.jpg > > > > gottfried > > > > > -----Ursprüngliche Nachricht----- > > > Von: gdalgorithms-list-admin@... > > > [mailto:gdalgorithms-list-admin@...]Im Auftrag von > > > David Zaadstra > > > Gesendet: Mittwoch, 27. Februar 2002 21:12 > > > An: gdalgorithms-list@... > > > Betreff: [Algorithms] midpoint displacement problems > > > > > > > > > Hello everybody, > > > > > > I have a problem with the midpoint displacement algorithm (from GPG1). > > > I get strange little peaks all around my landscape. I've been > > looking for > > > the bug for hours now and starting to believe that I'm a complete idiot. > > > Could it be that the peaks are normal? That would explain why an erosion > > > filter was added to the example file in GPG... > > > Please take a look at this screenshot to see what I mean: > > > http://www.gameprogramming.de/screen.jpg (not a very good one, i know) > > > > > > Thanks for your help, > > > David > > > > > > > > > _______________________________________________ > > > GDAlgorithms-list mailing list > > > GDAlgorithms-list@... > > > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > > > Archives: > > > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > > > > > > > > > > > _______________________________________________ > > GDAlgorithms-list mailing list > > GDAlgorithms-list@... > > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > > Archives: > > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > > > > > > _______________________________________________ > GDAlgorithms-list mailing list > GDAlgorithms-list@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=6188 > ```