Overhang Terrain Scene Manager - source released (page 5).

[Beauty]

Now I added photos and more information.
(It's not looking so much, but it took one whole hour. Wiki work can be so time consuming ... )

Every addition or improvement is welcome.
http://www.ogre3d.org/tikiwiki/Overhang ... ne+Manager

By the way:
The binary demo should also be uploaded to the repository. (to the "Downloads" section)
So it's save for the future in long-term.

[duststorm]

Now I added photos and more information.

Nice work!
The video really shows its features well. I can see this being very useful in a project where you would create caves or large underground spaces Both in a level editor as for making realtime holes.

[Beauty]

How the OverhangTerrainSM will be included?

Is it a replacement of the TerrainSceneManager?
(Because it's a modified version of TSM. ... And the TSM is an extended version of this - if I remember right.)

Or is the OverhangTSM side by side with the TSM?

In the file plugins.cfg of the demo the OctreeSceneManager is loaded.

Code: Select all

Plugin=Plugin_OctreeSceneManager

So I don't know the details.

In Ogre 1.8 the TSM is removed and the OctreeSceneManager is still available.
I suppose the TSM was removed because there were (file name?) conflicts with the new terrain component.
Has anybody an idea if the OverhangTerrainSM has good chances for Ogre 1.8?
Perhaps it has the same conflicts as the TSM.

[Beauty]

beaugard, your demo is nice for testing.
Unfortunately there is no source code.
It would be useful if you publish the source code, too.
So people could see how to set it up. Also they could play around by just modifying the demo code.

update:
I mean the source code of the demo

[drwbns]

When raycasting to newly built or ecavated terrain, the renderables don't show as movableObjects. Is there any way to modify the code to allow for this?

[DavlexDesign]

One thing that worries me about this thing, is ....

Don't know if you guys are looking at this but ...

With all the nice page handling of the new Terrain system, as soon as you edit a little bit of a page, that page remains at its highest res from then on, NOT GOOD for large terrains.

Now I know it's all early days yet, but wouldn't it be wise to incorporate a lodding on this before you go too far, because people will be requesting it later on.
To see what I mean, edit one piece and then hit the "R" key (so you can see the geometry), and pull away, you'll see that the terrain simplifies nicely, but only where there has been no editing with this algorithm. Won't take long for a terrain with only tiny mods in each page, for the terrain to blow out the ram.

Once I iron out my lodding properly for the destructibles, I may look at this thing too, haven't seen the code to this, but gather it is using some Marching Cubes incarnation.

Alex

[Beauty]

Is there any way to modify the code to allow for this?

The souce code is here:
https://code.google.com/p/ogre-overhang-terrain/
But I suppose it could be difficult to find the related lines of code.
Perhaps the author of the OverhangTSM can help you. If so, then you are a lucky boy.

By the way - in my last post I asked for the source code of the demo. (the SceneManager code itself is still available)

With all the nice page handling of the new Terrain system, as soon as you edit a little bit of a page, that page remains at its highest res from then on, NOT GOOD for large terrains.

Good to know this downside of the new terrain component.

[DavlexDesign]

G'day Beauty,

Good to know this downside of the new terrain component.

I am talking about this Overhang Terrain Scene Manager thingy, not the Ogre Terrain one, The new Ogre One works fine I think, it's this Overhang one that Creates a new Finest res page, and keeps it active at any distance, so the Ogre one can't reduce the edited pages' resolution any more.

Unless you plan on using this for small COD type levels, then this thing would be great, but for anything of any descent size, it will be pretty inefficient, don't get me wrong, (I thought foot in mouth disease was eradicated in AUS years ago), it's a great setup, but it is far from a complete solution when it comes to terrain.

Alex

[Beauty]

don't get me wrong

I like to hear about pratical experiences. You told us an important point.

[Beauty]

Perhaps it could be also useful for large terrain if it has many chunks and only one or a few of them are modified.

By the way:
I saw your planet rendering project long time ago. It was very impressive.
So you should have good experiences by terrain structure internals.
Unfortunately many sweet pictures of your topic are dead now.

[DavlexDesign]

G'day Beauty,

Unfortunately many sweet pictures of your topic are dead now.

I have plenty more to come, but this Overhang Terrain setup is definitely worth the effort to perfect.

Alex

[CallForSanity]

Hi,

for some reason I did not get notified about activity in this thread, so I wasn't aware there was any.
Sorry I did not notice earlier. So in response to some messages...

1. I did get it to work with Ogre 1.7.
Altough, in detail, it might be considered as a hack, because some source files from the OgreOctree code was copied.
A first step would be to remove those files and get it to work with the header files of the Ogre SDK and
to link against the right libraries.

2. I now has CMake build scripts included.
It compiles under Ubuntu x64 and Windows x32.
The demo runs under Ubuntu x64, but I did not test it under Windows.
I will upload the compiled demo soon.

3. I will give anybody who wants to commit to the project commit access to the repo.
Beauty has Admin access too, now.
The code has a lot of value in our opinion and at least I will try to make something useful out of it.

4. There is a bug which causes terrain patches to disappear under certain circumstances.
I was not able to solve that yet. It has something to do with the LOD level of unmodified terrain patches
surrounding a modified patch, that is my best guess. I will look further into it.

5. I am very much interested in further work, such as LOD, because I might be using it in another project.

6. It took me more than a day to understand the structure of the code.
If it is of interest I could write up an overview, that could help getting people into development faster.

Kind Regards,
CallForSanity

[Beauty]

Before somebody put much effort in improving, he should figure out if the OverhangTSM can get work with Ogre 1.8.
The TSM was removed, so perhaps the OverhangTSM can cause conflicts with the terrain component, too.

Also it seems so that there is no huge community interest in the OverhangTSM, because very long time nobody tried to update it to Ogre 1.7.

By the way:
Does the new terrain component supports overhangs and tunnels?

[Beauty]

for some reason I did not get notified about activity in this thread

When you write a post, you should look to the checkbox "Notify me when a reply is posted" below the text input area.
For me it's always checked. (If it's not checked for you, I suppose you can change the default value the forum setup.)
Also you should activate e-mail notification for replies in the forum setup.

Additionally you can scroll down at each forum topic. At the bottom is the button "suscribe topic". It's an alternative way to enable notifications. (e.g. if you forgot to activate the reply checkbox or if you want to follow a topic without creating a post.)

Thanks for sharing your knowledge and improved code.

[CallForSanity]

Additionally you can scroll down at each forum topic. At the bottom is the button "suscribe topic". It's an alternative way to enable notifications. (e.g. if you forgot to activate the reply checkbox or if you want to follow a topic without creating a post.)

Figured it out myself but thank you anyway!

Before somebody put much effort in improving, he should figure out if the OverhangTSM can get work with Ogre 1.8.
The TSM was removed, so perhaps the OverhangTSM can cause conflicts with the terrain component, too.

I didn't know there would be a new Terrain system in 1.8 yet, but since you mentioned it, I had a look into it.
From what I read, I believe the following.

The new terrain component is NOT implemented as a scene manager, which is the main difference.
I am quite certain it does not support tunnels, by the way.

Overhang terrain is in fact a scene manager.
That means it is not compatible with the new terrain system,
but OverhangTSM still RUN under Ogre 1.8,
because Ogre 1.8 will still know the concept of a scene manager.

Also, OverhangTSM is basically a modified source copy of TSM.
This is not very clean from a software engineering perspective,
but at least the new terrain component won't kill the project,
because there is no dependency in terms of linking from OverhangTSM to the old terrain component.

In the long term future of course, OverhangTSM should be ported to the new system.

I hope this makes sense.
CallForSanity

[beaugard]

hi, all.
I am the original author of this, first I have to say it is very cool that you are still working on this! I have largely given up non work-related programming, but my oldest kid is almost 5 so I'll have to come back soon in the name of education...

The OTM was meant as a proof-of-concept, so it has many ugly/unfinished parts, just because of lazyness. A LOD system is definitely one of them - the marching cubes approach lends itself quite well to this. You just have to sample the same 3d matrix with a coarser grid, will have a very small cpu/memory footprint to add lower-resolution version.

The problem is when switching LOD. Ideally, you'd do morphing, but it has to be in 3d instead of 1d like for a heightmap. Also, it is a bit messy because you cannot guarantee that there is something to morph from, for example a free-floating piece might not even exists in a lower LOD level. The alternative that I planned to implement for my cave system, was to fade-in LOD levels, where the lower LOD is always a little bit "eroded" (the threshold is a bit higher for what is "inside"). The erosion guarantees that you will see the high-LOD instead of the low-LOD when they are both on screen at the same time.

cheers, Martin

[Beauty]

because there is no dependency in terms of linking from OverhangTSM to the old terrain component.

Here is the post about the confict with the TerrainSceneManager:

Both the terrain manager and terrain component had a header with the same file name and similar but not identical content (ogreterrainprerequisites.h). That was a real pain in the ass for my custom ogre framework. So I was incredibly glad when I saw the terrain manager was removed.

It's from a fresh forum topic about, which contains useful terrain information:
[Split] Insight information about the SceneManager

I am the original author

Nice to hear your voice.

[drwbns]

Beaugard,

I started out trying to use OTSM for adding raycasting to terrain, but I ran into many problems as I discussed here- http://www.ogre3d.org/forums/viewtopic.php?f=2&t=67636 I solved all the raycasting issues in OTSM and new Terrain component except for finding newly built terrain and/or excavated terrain in OTSM as seen in this post - http://www.ogre3d.org/forums/viewtopic. ... 36#p445836

I've tried to implement a simple isosurfaces demo in new Terrain Manager with nothing but headaches. I can't get MetaBalls to display properly, if at all. I'm not sure if I need > 1 sceneNodes or > 1 isoSurfaces or > 1 dataGrids. I was hoping you maybe had some insight into the answers .

I also wanted to post my isoSurface code for new Terrain Manager in hopes someone could figure out why MetaBalls aren't being displayed. I'm not really sure which update functions I should be calling. Here's left mouse click function -

Code: Select all

	if(mMouse->getMouseState().buttonDown(OIS::MB_Left)) {
		Ray mouseRay = mTrayMgr->getCursorRay(mCamera);
		mouseRay.setOrigin(mCamera->getPosition());
		Ogre::RaySceneQuery* mRayScnQuery = mSceneMgr->createRayQuery(Ogre::Ray());
		mRayScnQuery->setQueryMask(Ogre::SceneManager::WORLD_GEOMETRY_TYPE_MASK);
		mRayScnQuery->setRay(mouseRay);
		mRayScnQuery->setSortByDistance(true);
		Ogre::RaySceneQueryResult& result = mRayScnQuery->execute();
		Ogre::RaySceneQueryResult::iterator iter = result.begin();

		MetaObjectDataGrid * dataGridPtr = new MetaObjectDataGrid;
		DataGrid* mDataGrid = static_cast<DataGrid*>(dataGridPtr);
		for(iter; iter != result.end(); iter++)
		{
			if(iter->distance < 10) continue;
			if(iter->movable->getName() != "" ) {
				
				dataGridPtr->initialize(msNumCells, msNumCells, msNumCells, msWidth/msNumCells, DataGrid::HAS_GRADIENT/* | DataGrid::HAS_COLOURS*/);
				if(!iso) {
					iso = new CubeIsoSurface();
					iso->initialize(mDataGrid, IsoSurface::GEN_NORMALS/* | IsoSurface::GEN_VERTEX_COLOURS/* | IsoSurface::GEN_TEX_COORDS*/);
					
					iso->setIsoValue(0.15);
					iso->setMaterial("OverhangTerrain_simple");
					iso->setNormalType(IsoSurface::NORMAL_AVERAGE);
					
					// Create a scene node and attach the iso surface
					sceneNode = mSceneMgr->getRootSceneNode()->createChildSceneNode();
					sceneNode->attachObject(iso);
				}
				//sceneNode->setPosition(mouseRay.getOrigin() + mouseRay.getDirection() * iter->distance);
				mDataGrid->setPosition(mouseRay.getOrigin() + mouseRay.getDirection() * iter->distance); // causes ball to disappear
				MetaBall * mo = new MetaBall(mouseRay.getOrigin() + mouseRay.getDirection() * iter->distance);
				//mo->setPosition(mouseRay.getOrigin() + mouseRay.getDirection() * iter->distance);
				MetaObject * metaOBJ = dataGridPtr->addMetaObject(mo);
				metaOBJ->updateDataGrid(dataGridPtr);
				//dataGridPtr->update();
				
				//iso->getDataGridPtr()->update();
				iso->update();
				
				hitMovable = true;
				//dataGrid->clearMetaObjects();
				break;
			}
			if(iter->worldFragment) {
				dataGridPtr->addMetaObject(new MetaBall);
				break;
			}
		}
		if (!hitMovable) {
			//mouseRay.setOrigin(mCamera->getPosition());
			//mouseRay.setDirection(mCamera->getDirection());

			Ogre::TerrainGroup::RayResult RayResult = mTerrainGroup->rayIntersects(mouseRay);
			if(RayResult.hit) {
				MetaObjectDataGrid * dataGridPtr = new MetaObjectDataGrid;
				DataGrid* mDataGrid = static_cast<DataGrid*>(dataGridPtr);
				dataGridPtr->initialize(msNumCells, msNumCells, msNumCells, msWidth/msNumCells, DataGrid::HAS_GRADIENT/* | DataGrid::HAS_COLOURS*/);
				if(!iso) {
					iso = new CubeIsoSurface();
					iso->initialize(mDataGrid, IsoSurface::GEN_NORMALS/* | IsoSurface::GEN_VERTEX_COLOURS/* | IsoSurface::GEN_TEX_COORDS*/);
					
					iso->setIsoValue(0.15);
					iso->setMaterial("OverhangTerrain_simple");
					iso->setNormalType(IsoSurface::NORMAL_AVERAGE);
					
					// Create a scene node and attach the iso surface
					sceneNode = mSceneMgr->getRootSceneNode()->createChildSceneNode();
					sceneNode->attachObject(iso);
				}
				
				 //Create a scene node and attach the iso surface
				sceneNode = mSceneMgr->getRootSceneNode()->createChildSceneNode();
				sceneNode->attachObject(iso);
				sceneNode->showBoundingBox(true);
				//sceneNode->setPosition(RayResult.position);
				mDataGrid->setPosition(RayResult.position); // causes ball to disappear
				//dataGrid = new MetaObjectDataGrid();
				MetaBall * mo = new MetaBall(RayResult.position);
				//mo->setPosition(RayResult.position);
				MetaObject *  MetaOBJ = dataGridPtr->addMetaObject(mo);
				MetaOBJ->updateDataGrid(mDataGrid);
				mo->updateDataGrid(mDataGrid);
				
				mDataGrid->update();
				iso->setVisible(true);
				iso->getDataGridPtr()->update();
				iso->update();
				dataGridPtr->clear();
				//dataGrid->clearMetaObjects();
			}
		}
		hitMovable = false;
	}

[Beauty]

I started out trying to use OTSM

I suppose you mean OverhangTSM. But I'm not shure, because OTSM also could mean OcTreeSceneManager. If you mean second, please give us a hint.

raycasting to terrain, but I ran into many problems

Ray query for terrain is very imprecise for the TerrainSceneManager (the returned distance value is up to one Ogre Unit too large).
For this problem I created a workaround, which is easy to use:
http://www.ogre3d.org/forums/viewtopic. ... 00#p444900

new Terrain Manager

What you mean?
The new terrain component of Ogre? (It is no scene manager)
Or the OverhangTSM? (zip download link)
Or the improved code of OverhangTSM? (repository)
Something else?

[drwbns]

Yes, OverhangTSM. The raycasting problem is not because of imprecise distances, it is because added terrain isn't a world fragment or a movable object in OverhangTSM. And, yes. I meant new Terrain Component which is not a scene manager like you said.

[jacmoe]

So many questions!

Regarding Drwbns: just dumping code for others to debug, as usual.

I might be too harsh, but it's not far from the truth.

[drwbns]

Just looking for help Jacmoe

[jacmoe]

So, it's using MetaBalls then ?
What exactly are they ?
SimpleRenderables ?
Ogre needs some data to be able to render them - normally it's indices and vertices which means that you can use it for collision detection too.

[drwbns]

A MetaBall is a MetaObject. The MetaObjects are told to update the IsoSurfaceBuilder's DataGrid. MetaWorldFragment::mSurf is an IsoSurfaceRenderable which initializes the IsoSurfaceBuilder called from MetaWorldFragment->update. mSurf is a DynamicRenderable which is a SimpleRenderable which is a MovableObject that is created if MetaWorldFragment doesn't have a mSurf already. That's all I got so far, I'll try to lay out the rest.

[Beauty]

The raycasting problem is not because of imprecise distances

There is an impreciseness and my workaround fix it.
Here is the description how it works.

the algorithm just rides along the ray in 1 unit steps and checks if it's over or under the terrain. It stops in the latter case.

Well, you talk about an other problem. I just wanted to explain for what my workaround is related to.

added terrain isn't a world fragment or a movable object

Very strange. I thought every "detectable object" would return a RayQueryResultEntry as worldFragment of movableObject.

SimpleRenderables ?
Ogre needs some data to be able to render them - normally it's indices and vertices

I don't know how to access SimpleRenderables, but I suppose it's similar to entities/meshes and ManualObjects.

Code examples for vertices/indices:
* Access to meshes/entities you find here.
* Access to ManualObjects you find here.