building turrain using subdivisional triangles

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ClymAngus
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building turrain using subdivisional triangles

Post by ClymAngus »

I saw something interesting the other day. My linux screen saver went on random, and it landed on "Triangles" the principle appears to be fairly simple take a triangle then slowly devide it into more triangles by subdividing each existing one into 4.
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/ \
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the hight of each new point is constrained by the ones around it. enabling the quick drawing of turrain with lots of options like.

colouration at a set hight.
flat sea level.
varying degrees of quality depending on the viewing distance, pc power
technically you could set points getting variations on a theme if you have a pre-built planet.

Plus you would be able to fly around it!

Here are some links if you want some further reading:
http://www.jwz.org/xscreensaver/screenshots/
(triangle is about 4/5ths down the page:
Image

it was written by this dude:
http://www.spoke.com/info/p95l2DC/TobiasGloth

Image

http://linux.die.net/man/1/triangle

If any mac or linux bod wants to try and hack the code out of the original;
http://www.jwz.org/xscreensaver/download.html
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Post by Griff »

oo, that looks like the 'Zarch' game that i used to gawp at in amazement in the window of the computer shop in Swansea when i was in there buying games for my C64
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Post by DaddyHoggy »

We use this technique a lot in Sythnetic Environments - we use TINs (triangulated irregular network) to control Level of Detail (LODs) - underlying database is high detail but distant mountains made up of few big polygons but as you approach the TINs subdivide into ever more complex triangles without any noticeable snapping from one LOD to the next.

Most of the big (expensive) Terrain building systems (such as TerraVista) build TIN LODs into their Scenegraphs.

(Given the shapes of most of the classic ships a similar technique could have been used to LOD the ships - point of clarification - does Oolite have LOD built in?)

If you're interested I could dig out some of my lecture notes on the subject?

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Post by DaddyHoggy »

Griff wrote:
oo, that looks like the 'Zarch' game that i used to gawp at in amazement in the window of the computer shop in Swansea when i was in there buying games for my C64
I played Zarch (and Virus?) on an Acorn Achimedes - RISC processor and a stunning machine for its time...
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Post by DaddyHoggy »

I found this - to get the ball rolling (it's not one of mine!) - this technique combined with LIDAR makes for some amazing terrains.

http://www.geocities.com/Area51/Rampart/2501/prof.html
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Post by zevans »

Never mind Zarch on the Arch... I remember a proggy on the BBC that did this...

On a pretty small grid, and it was isometric, admittedly, but the concept was there and you could change the level of the water and stuff... pretty cool back then.
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Post by Griff »

i'm sure i read somewhere that this chopping up of polygons into smaller and smaller ones is going to be a big feature in the next lot of graphics cards, or maybe it was Microsoft's directx 11 or something, although i also saw somewhere that we're all going to go back to using voxels too!

yeah, seeing Zarch running in the computer shop was pretty spectacular, i never got to play it though, although i did play a lot of zee-wolf 2 on my old Amiga, ah what a great game that was, although i was really bad at it.
seeing 'Quake' running for the first time on my brother-in-laws pc was a similar moment, i remember thinking 'blimey, it's just like the Knightmare show on tv!'
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Post by ClymAngus »

DaddyHoggy wrote:
We use this technique a lot in Sythnetic Environments - we use TINs (triangulated irregular network) to control Level of Detail (LODs) - underlying database is high detail but distant mountains made up of few big polygons but as you approach the TINs subdivide into ever more complex triangles without any noticeable snapping from one LOD to the next.

Most of the big (expensive) Terrain building systems (such as TerraVista) build TIN LODs into their Scenegraphs.

(Given the shapes of most of the classic ships a similar technique could have been used to LOD the ships - point of clarification - does Oolite have LOD built in?)

If you're interested I could dig out some of my lecture notes on the subject?

DH
Sweet dig it out. Any chance to play slarty bartfast.
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Post by Frame »

Griff wrote:
i'm sure i read somewhere that this chopping up of polygons into smaller and smaller ones is going to be a big feature in the next lot of graphics cards, or maybe it was Microsoft's directx 11 or something, although i also saw somewhere that we're all going to go back to using voxels too!

yeah, seeing Zarch running in the computer shop was pretty spectacular, i never got to play it though, although i did play a lot of zee-wolf 2 on my old Amiga, ah what a great game that was, although i was really bad at it.
seeing 'Quake' running for the first time on my brother-in-laws pc was a similar moment, i remember thinking 'blimey, it's just like the Knightmare show on tv!'
Voxels ? dear lord I hope not, this is more a thing of the past when resolutions where not that high..

Quake: oh yeah, I remember clearly having already bought my computer in 1995 and running Quake on a P 133 with windows 95.. just seeing him swim was incredible.

Guess how I started gasping when I saw 3dfx cards, and bought one.. now suddenly I could see people below the water, and of course shot them. or axe them. me favourite.. Axe Them... ^^

oh and not forgetting Descent...

http://en.wikipedia.org/wiki/Descent_%28video_game%29
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Post by DaddyHoggy »

Frame wrote:
Griff wrote:
i'm sure i read somewhere that this chopping up of polygons into smaller and smaller ones is going to be a big feature in the next lot of graphics cards, or maybe it was Microsoft's directx 11 or something, although i also saw somewhere that we're all going to go back to using voxels too!

yeah, seeing Zarch running in the computer shop was pretty spectacular, i never got to play it though, although i did play a lot of zee-wolf 2 on my old Amiga, ah what a great game that was, although i was really bad at it.
seeing 'Quake' running for the first time on my brother-in-laws pc was a similar moment, i remember thinking 'blimey, it's just like the Knightmare show on tv!'
Voxels ? dear lord I hope not, this is more a thing of the past when resolutions where not that high..

Quake: oh yeah, I remember clearly having already bought my computer in 1995 and running Quake on a P 133 with windows 95.. just seeing him swim was incredible.

Guess how I started gasping when I saw 3dfx cards, and bought one.. now suddenly I could see people below the water, and of course shot them. or axe them. me favourite.. Axe Them... ^^

oh and not forgetting Descent...

http://en.wikipedia.org/wiki/Descent_%28video_game%29
I sold my copy of the original Descent and Freespace (Great War) plus a 3Dfx Voodoo5 5500 on eBay last year for a surprisingly large amount of money! (well it surprised me how much somebody would pay for a fairly bad AGP 1x only gfx card that barely fits in most modern small cases!)
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Re: building turrain using subdivisional triangles

Post by JensAyton »

ClymAngus wrote:
I saw something interesting the other day. My linux screen saver went on random, and it landed on "Triangles" the principle appears to be fairly simple take a triangle then slowly devide it into more triangles by subdividing each existing one into 4.
To be honest, this is a pretty ancient method of terrain generation. It only looks good over small areas, since it can only generate stuff that looks like young mountain ranges of essentially uniform height.
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Post by Griff »

did you get the first Tomb Raider game frame? the patch they made to take advantage of the 3dfx card was really amazing, certainly put my matrox mystique graphic card to shame :lol:
did the Frontier games do an early version of this polygon subdivision for the planets or am i remembering incorrectly? it could have just been early texture mapping going wonky and different levels of detail models popping in suddenly when approaching a planet that make me think it was subdividing the model automatically.
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Re: building turrain using subdivisional triangles

Post by ClymAngus »

Ahruman wrote:
ClymAngus wrote:
I saw something interesting the other day. My linux screen saver went on random, and it landed on "Triangles" the principle appears to be fairly simple take a triangle then slowly devide it into more triangles by subdividing each existing one into 4.
To be honest, this is a pretty ancient method of terrain generation. It only looks good over small areas, since it can only generate stuff that looks like young mountain ranges of essentially uniform height.
Fair comment but it starts a conversation. So what would you use :)
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Post by DaddyHoggy »

Can't speak for Ahruman (who seems to know somethng about everything!) but TINs as I described earlier can create some quite dramatic terrains for not a huge overhead (just some clever edge matching when a near TIN with lots of triangles meets a far TIN with far less triangles)
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