Creating manual mesh in Ogre3d?

Question

I am getting a bit confused as to why my manually created mesh is not appearing correctly. I have created the vertex and index buffers and they seem (although I am not 100% sure) to contain the correct values.

Essentially I am creating a grid of mapSize * mapSize vetrices, at a height of 0, then creating the triangles out of them.

void TerrainGeneration::createTerrainMesh() {
  /// Create the mesh via the MeshManager
      Ogre::MeshPtr msh = Ogre::MeshManager::getSingleton().createManual("TerrainTest", "General");
  Ogre::SubMesh* sub = msh->createSubMesh();

  const size_t nVertices = mapSize*mapSize;
  const size_t vbufCount = 3*2*nVertices;

  float vertices[vbufCount];

  size_t vBufCounter = 0;
  for(int z = 0; z < mapSize; z++) {
          for(int x = 0; x < mapSize; x++) {
          //Position
      vertices[vBufCounter] = x;
      vertices[vBufCounter+1] = 0;
      vertices[vBufCounter+2] = z;
      //Normal
      vertices[vBufCounter+3] = 0;
      vertices[vBufCounter+4] = 1;
      vertices[vBufCounter+5] = 0;

      vBufCounter += 6;
      }
  }

  Ogre::RenderSystem* rs = Ogre::Root::getSingleton().getRenderSystem();
      Ogre::RGBA colours[nVertices];
      Ogre::RGBA *pColour = colours;

  //Create triangles
  const size_t ibufCount = 6*(mapSize - 1)*(mapSize - 1);
  unsigned int faces[ibufCount];

  size_t iBufCounter = 0;
  for(int x=0; x <= mapSize -2; x++) {
    for(int y=0; y <= mapSize -2; y++) {
        faces[iBufCounter] = vertices[(y*mapSize) + x];
        faces[iBufCounter+1] = vertices[((y+1)*mapSize) + x];
        faces[iBufCounter+2] = vertices[((y+1)*mapSize) + (x+1)];

        faces[iBufCounter+3] = vertices[(y*mapSize) + x];
        faces[iBufCounter+4] = vertices[((y+1)*mapSize) + (x+1)];
        faces[iBufCounter+5] = vertices[(y*mapSize) + (x+1)];

        iBufCounter += 6;
    }
}









/// Create vertex data structure for n*n vertices shared between submeshes
    msh->sharedVertexData = new Ogre::VertexData();
    msh->sharedVertexData->vertexCount = nVertices;

/// Create declaration (memory format) of vertex data
    Ogre::VertexDeclaration* decl = msh->sharedVertexData->vertexDeclaration;
    size_t offset = 0;
    // 1st buffer
    decl->addElement(0, offset, Ogre::VET_FLOAT3, Ogre::VES_POSITION);
    offset += Ogre::VertexElement::getTypeSize(Ogre::VET_FLOAT3);
    decl->addElement(0, offset, Ogre::VET_FLOAT3, Ogre::VES_NORMAL);
    offset += Ogre::VertexElement::getTypeSize(Ogre::VET_FLOAT3);
    /// Allocate vertex buffer of the requested number of vertices (vertexCount) 
    /// and bytes per vertex (offset)
    Ogre::HardwareVertexBufferSharedPtr vbuf = 
    Ogre::HardwareBufferManager::getSingleton().createVertexBuffer(
    offset, msh->sharedVertexData->vertexCount, Ogre::HardwareBuffer::HBU_STATIC_WRITE_ONLY);
    /// Upload the vertex data to the card
    vbuf->writeData(0, vbuf->getSizeInBytes(), vertices, true);

    /// Set vertex buffer binding so buffer 0 is bound to our vertex buffer
    Ogre::VertexBufferBinding* bind = msh->sharedVertexData->vertexBufferBinding; 
    bind->setBinding(0, vbuf);

    /// Allocate index buffer of the requested number of vertices (ibufCount) 
    Ogre::HardwareIndexBufferSharedPtr ibuf = Ogre::HardwareBufferManager::getSingleton().
    createIndexBuffer(
    Ogre::HardwareIndexBuffer::IT_16BIT, 
    ibufCount, 
    Ogre::HardwareBuffer::HBU_STATIC_WRITE_ONLY);

    /// Upload the index data to the card
    ibuf->writeData(0, ibuf->getSizeInBytes(), faces, true);

    /// Set parameters of the submesh
    sub->useSharedVertices = true;
    sub->indexData->indexBuffer = ibuf;
    sub->indexData->indexCount = ibufCount;
    sub->indexData->indexStart = 0;

    /// Set bounding information (for culling)
    msh->_setBounds(Ogre::AxisAlignedBox(-5000,-5000,-5000,5000,5000,5000));
    //msh->_setBoundingSphereRadius(Ogre::Math::Sqrt(3*100*100));

    /// Notify -Mesh object that it has been loaded
    msh->load();

}

I initialise the mesh and load it as follows

Ogre::Entity* thisEntity = mSceneMgr->createEntity("cc", "TerrainTest", "General");
thisEntity->setMaterialName("Examples/Rockwall");
Ogre::SceneNode* thisSceneNode = mSceneMgr->getRootSceneNode()->createChildSceneNode();
thisSceneNode->setPosition(0, 0, 0);
thisSceneNode->attachObject(thisEntity);

Any insight would be greatly appreciated.

Answer 1

Ok so I got an answer off the Ogre3d forums from a very helpful person called bstone.

It turns out that when creating my index list to create the faces I was mistakenly passing coordinates from the vertex list rather than indexes of the vertices.

 faces[iBufCounter] = vertices[(y*mapSize) + x];
 faces[iBufCounter+1] = vertices[((y+1)*mapSize) + x];
 faces[iBufCounter+2] = vertices[((y+1)*mapSize) + (x+1)];

 faces[iBufCounter+3] = vertices[(y*mapSize) + x];
 faces[iBufCounter+4] = vertices[((y+1)*mapSize) + (x+1)];
 faces[iBufCounter+5] = vertices[(y*mapSize) + (x+1)];

Should have been

 faces[iBufCounter] = (y*mapSize) + x;
 faces[iBufCounter+1] = ((y+1)*mapSize) + x;
 faces[iBufCounter+2] = ((y+1)*mapSize) + (x+1);

 faces[iBufCounter+3] = (y*mapSize) + x;
 faces[iBufCounter+4] = ((y+1)*mapSize) + (x+1);
 faces[iBufCounter+5] = (y*mapSize) + (x+1);

However I still have a problem in my code somewhere, although from what others have said it probably isn't in this code that i've posted.

Another user also proposed that I create the terrain ina much simpler way and posted the following code

int mapSize = 16;
Ogre::ManualObject *man = m_sceneManager->createManualObject("TerrainTest");
man->begin("Examples/Rockwall",Ogre::RenderOperation::OT_TRIANGLE_LIST);
for(int z = 0; z < mapSize; ++z)
{
   for(int x = 0; x < mapSize; ++x)
   {
      man->position(x,0,z);
      man->normal(0,1,0);
      man->textureCoord(x,z);
   }
}
for(int z = 0; z < mapSize-1; ++z)
{
   for(int x = 0; x < mapSize-1; ++x)
   {
      man->quad((x) + (z) * mapSize, (x) + (z + 1) * mapSize, (x + 1) + (z + 1) * mapSize, (x + 1) + (z) * mapSize);
   }
}
man->end();
m_sceneManager->getRootSceneNode()->attachObject(man);