Ogre3D 1.7 export

jacmoe · **Posted:** Fri Jan 22, 2010 1:13 pm

This is a guide for exporting a terrain made in PnP TerrainCreator to Ogre 1.7.

We are using demoterrain, and due to the limit of 6 image layers per terrain page in Ogre, we are going to retexture it, using the following 4 textures:
gras.jpg | slope: 0 - 50 | height: 35 - 20000
moos1.jpg | slope: 35 - 90 | height: 0 - 35
moos2.jpg | slope: 50 - 90
schlamm_getrocknet2.jpg | slope: 0 - 35 | height: 0 - 35

Use power of four textures!
The nVidia texture tool needs them to be of that size, eg 512.

Setup the texture plugin using the above automated texturing parameters, and retexture the terrain.

You should see something like this:

Attachment:

pnptc_terrain.jpg [ 59.29 KiB | Viewed 99 times ]

(Sorry about the lack of light)

The limit of 6 layers is when using a global light map and a normal map, and then diffuse/specular, normal/height maps for the layer textures.
A SM2 card has a limit of 16 texture units in one pass.
It is possible to write your own multi-pass material generator, though. Making it possible to use more textures.

Now we are going to export it to Ogre.

First, we need to export the heightmap.
Right-click on the terrain page and select the RAW heightmap export plugin, using the following settings:

Attachment:

heightmapExport.jpg [ 13.64 KiB | Viewed 2365 times ]

This should give a full scale RAW heightmap file.

Next, we need to export the splatting maps.
Choose the alphamap export plugin, and use the following settings:

Attachment:

alphamapExport.jpg [ 19.46 KiB | Viewed 2363 times ]

Would probably be a good idea to check power of two.

Should leave you with the following textures:
gras_00000_00000_000.PNG
moos1_00000_00000_000.PNG
moos2_00000_00000_000.PNG
schlamm_getrocknet2_00000_00000_000.PNG

Now, we need to turn the four diffuse textures into what the default Ogre terrain material generator expects:
diffuse_specular and normal_height.

Here's one way to generate those textures:

1) Get ShaderMap CL from http://www.shadermap.renderingsystems.com/
2) Create a bat file with the following contents:

Code:

CD "C:\Program Files\ShaderMap CL 1.2.2"

START /WAIT shadermap.exe cdiff "<texture_directory>\<texture_name>" -disp (60,100,12,xy) -norm (100,200,xy,0) -spec (100,-50,52,xy) -v 

Replace the directory and texture name with what you want to generate maps for.

3) Generate the maps by running the bat script, once for each texture.

4) Use the following code to combine the images:

Code:

   Ogre::Image combined;

   combined.loadTwoImagesAsRGBA("moos1.jpg", "moos1_SPEC.bmp", 
      Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, Ogre::PF_BYTE_RGBA);
   combined.save("moos1_diffusespecular.png");

   combined.loadTwoImagesAsRGBA("moos1_NORM.tga", "moos1_DISP.bmp", 
      Ogre::ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME, Ogre::PF_BYTE_RGBA);
   combined.save("moos1_normalheight.png");

You need to have the 16 source texture somewhere in declared resource location, so just put a directory called terraintex in 'media' and add a line to resources.cfg so that Ogre picks it up, ie '../media/terraintex'

5) Get the nVidida texture tools (DDS Utilities) and convert the output textures to dds.
Place the generated png's in the ddsutilities directory, open up a console and run this:

Code:

nvdxt.exe -all -dxt3

6) Done.

Of course, you can replace step 4 with whatever method you have to load a greyscale map into the alphachannel, using Photoshop or the Gimp or any other tool.

Now we have a heightmap, a set of 8 textures and 4 alphamap textures.
And we are ready to load that into Ogre.

Code:

   // a light for the ligthmap
   Ogre::Vector3 lightdir(0, -0.3, 0.75);
   lightdir.normalise();
   Ogre::Light* l = sceneMgr->createLight("tstLight");
   l->setType(Ogre::Light::LT_DIRECTIONAL);
   l->setDirection(lightdir);
   l->setDiffuseColour(Ogre::ColourValue(1.0, 1.0, 1.0));
   l->setSpecularColour(Ogre::ColourValue(0.4, 0.4, 0.4));
   sceneMgr->setAmbientLight(Ogre::ColourValue(0.6, 0.6, 0.6));

   // global terrain options
   Ogre::TerrainGlobalOptions::setMaxPixelError(1); // set to 1 if using 1 unit/1 metre (ie pagesize of 1024)
   Ogre::TerrainGlobalOptions::setCompositeMapDistance(2000);
   Ogre::TerrainGlobalOptions::setLightMapDirection(lightdir);
   Ogre::TerrainGlobalOptions::setCompositeMapAmbient(sceneMgr->getAmbientLight());
   Ogre::TerrainGlobalOptions::setCompositeMapDiffuse(l->getDiffuseColour());

   // create new instance of Ogre::Terrain
   mTerrain = OGRE_NEW Ogre::Terrain(sceneMgr);

   // load the heightmap from the RAW file
   Ogre::DataStreamPtr stream = Ogre::ResourceGroupManager::getSingleton().openResource("demoraw.raw", "General" );
   size_t size = stream.get()->size();
   if(size != 1025 * 1025 * 4)
   {
      OGRE_EXCEPT( Ogre::Exception::ERR_INTERNAL_ERROR, "Size of stream does not match terrainsize!", "TerrainPage" );
   }
   float* buffer = OGRE_ALLOC_T(float, size, Ogre::MEMCATEGORY_GENERAL);
   stream->read(buffer, size);

   // import settings
   Ogre::Terrain::ImportData imp;
   imp.terrainSize = 1025;
   imp.worldSize = 1024;
   imp.inputFloat = buffer;
   imp.minBatchSize = 33;
   imp.maxBatchSize = 65;

   // textures
   imp.layerList.resize(4);
   imp.layerList[0].textureNames.push_back("gras_diffusespecular.dds");
   imp.layerList[0].textureNames.push_back("gras_normalheight.dds");
   imp.layerList[0].worldSize = 30;
   imp.layerList[1].textureNames.push_back("moos1_diffusespecular.dds");
   imp.layerList[1].textureNames.push_back("moos1_normalheight.dds");
   imp.layerList[1].worldSize = 30;
   imp.layerList[2].textureNames.push_back("schlamm_getrocknet2_diffusespecular.dds");
   imp.layerList[2].textureNames.push_back("schlamm_getrocknet2_normalheight.dds");
   imp.layerList[2].worldSize = 30;
   imp.layerList[3].textureNames.push_back("moos2_diffusespecular.dds");
   imp.layerList[3].textureNames.push_back("moos2_normalheight.dds");
   imp.layerList[3].worldSize = 20;

   mTerrain->prepare(imp);
   mTerrain->load();

   // blend maps (alphamaps)
   Ogre::String blendImages[4];
   blendImages[0] = "gras_00000_00000_000.PNG";
   blendImages[1] = "moos1_00000_00000_000.PNG";
   blendImages[2] = "schlamm_getrocknet2_00000_00000_000.PNG";
   blendImages[3] = "moos2_00000_00000_000.PNG";

   // load those blendmaps into the layers
   for(int j = 1;j < mTerrain->getLayerCount();j++)
   {
      Ogre::TerrainLayerBlendMap *blendmap = mTerrain->getLayerBlendMap(j);
      Ogre::Image img;
      img.load(blendImages[j],"General");
      int blendmapsize = mTerrain->getLayerBlendMapSize();
      if(img.getWidth() != blendmapsize)
         img.resize(blendmapsize, blendmapsize);

      float *ptr = blendmap->getBlendPointer();
      Ogre::uint8 *data = static_cast<Ogre::uint8*>(img.getPixelBox().data);

      for(int bp = 0;bp < blendmapsize * blendmapsize;bp++)
         ptr[bp] = static_cast<float>(data[bp]) / 255.0f;

      blendmap->dirty();
      blendmap->update();
   }

   // clean up
   mTerrain->freeTemporaryResources();

   // adjust the position of the terrain (Ogre uses the centre of the terrain as 0,0,0
   mTerrain->setPosition(Ogre::Vector3(512,0,512));

So, all we need is to compile and run our terrain application, and this is what we see:

Attachment:

screenshot01222010_152120213.jpg [ 105.03 KiB | Viewed 118 times ]

jacmoe · **Posted:** Fri Jan 22, 2010 4:14 pm

This tutorial is now written. :wink:

jacmoe · **Posted:** Fri Jan 22, 2010 10:37 pm

Notice that there are no configuration files here. Everything is done in code. :wink:

It's very flexible, so the route I took in the mini-tutorial isn't the only route.

I'll get back to this topic when the paging has been fully implemented, and give an example of exporting/importing multiple terrain pages.

jacmoe · **Posted:** Mon Feb 01, 2010 2:23 pm

I am almost ready to write a section on how to use multiple terrain pages with Ogre 1.7 - as soon as I've got a clean test application up, I'll update this topic.

jacmoe · **Posted:** Mon Feb 01, 2010 3:17 pm

One small request:

The Ogre scene exporter translates the y component by pagesize, because the Ogre 1.6 terrain has it's origin at the opposite corner of the terrain than PnPTC (x forward, z left)
However, the new terrain component has the origin at the centre.

Right now, I take that into account by manually adjusting object positions, like this:

Code:

Ogre::Vector3 adjust(pagesize * 0.5, 0, pagesize * 0.5);
Ogre::Vector3 house2_pos(111.603996, 1834.977295, 885.291992);
house2_pos -= adjust;

Then they match up with the terrain page.
Now, for each page, I do this:

Code:

        Ogre::Vector3 offset(Ogre::Vector3::ZERO);
   mTerrainPage->getTerrainGroup()->convertTerrainSlotToWorldPosition(1,0, &offset);
   house2_pos += offset;

That code converts the object position to world position.

Would be nice to have the option of choosing the origin.

Ralf · **Posted:** Mon Feb 01, 2010 9:51 pm

How do you export object positions? Do you use the ogre scene xml exporter? I could add such an option to it.

jacmoe · **Posted:** Mon Feb 01, 2010 9:55 pm

I use the Ogre scene exporter, and it's perfect.

The only thing I would want is the option of choosing between origin at the centre of the terrain, or at the corner (which is the current option)

Ralf · **Posted:** Mon Feb 01, 2010 9:57 pm

Ok, I'll add this option and post the updated exorter here.

jacmoe · **Posted:** Mon Feb 01, 2010 10:04 pm

It's at line 478 in PnPTCOgreSceneExportPlugin.cpp:

Code:

      
            // we need to move z pagesize units, since the terrain origin in Ogre3D is at x/z 0 with y up, whereas PnPTC is x/y 0 with z up.
            vecPos.z = iPatchSize - vecPos.z;

So it would probably be:

Code:

      
            vecPos.y = iPatchSize*0.5 - vecPos.y;
            vecPos.z = iPatchSize*0.5 - vecPos.z;

Or, even better:

Code:

vecPos.y -= adjustVector;

Where the adjustVector is either (iPatchSize,0,0) or (iPatchSize*0.f,0,iPatchSize*0.5) - off the top of my head.
Not sure.

jacmoe · **Posted:** Tue Feb 02, 2010 4:25 pm

I just updated the mini-tutorial to using a max pixel-error of 1, instead of 8.
Otherwise the terrain will not be accurate enough for the default scale (1 metre to 1 unit).

If you're curious, here's the difference between a max pixel error of 8, and a max pixel error of 1:

Attachment:

File comment: Ogre::TerrainGlobalOptions::setMaxPixelError(8);

screenshot02012010_000505777.jpg [ 91.36 KiB | Viewed 46 times ]

Attachment:

File comment: Ogre::TerrainGlobalOptions::setMaxPixelError(1);

screenshot02012010_151240458.jpg [ 94.11 KiB | Viewed 48 times ]

So, a big difference.

Had me stumped for over a week, this one.

jacmoe · **Posted:** Thu Jun 24, 2010 8:54 pm

Could you please fix the images?

There's absolutely no use in putting a lot of work into making a tutorial and uploading images when they're not kept...

Ralf · **Posted:** Fri Jun 25, 2010 2:22 pm

Sorry for this, we moved to a new server a couple of days ago. As it seems, some of the attachment files got lost on the way. I restored them; so all images should be back again.

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Ogre3D 1.7 export

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