Creating manual mesh in Ogre3d? - c++

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);