1. Presented by 鄭游駿(Yu-Chun Cheng) 2009/11/27
Ogre Manual Mesh
Presented by
鄭游駿(Yu-Chun Cheng)
2009/11/27

2. Step Create a mesh Create a submesh
Decide whether you want to share vertex data or not, and then create vertex data
Define static buffer for vertex position, normal, texture coordinate, and vertex index
Set data of all buffers
Set vertex buffer bindings
Set vertex buffer declaration
Define the bound of the mesh

3. Create a mesh MeshPtr mesh = MeshManager::getSingleton().createManual(
“myMesh”, // mesh name
ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME // the group name which mesh belongs to );

4. Create a submesh
SubMesh* subMesh = mesh->createSubMesh();

5. Decide whether you want to share vertex data or not, and then create vertex data
// By default, the value is true
subMesh->useSharedVertices = false;
subMesh->vertexData = new VertexData();
subMesh->vertexData->vertexStart = 0;
subMesh->vertexData->vertexCount = numVertices; 1 1 2 3 2 3 4 5 4 6

6. Define static buffer for vertex position, normal, texture coordinate, and vertex index
HardwareVertexBufferSharedPtr posVertexBuffer;
HardwareVertexBufferSharedPtr normalVertexBuffer;
HardwareVertexBufferSharedPtr texVertexBuffer;
HardwareIndexBufferSharedPtr indexBuffer;

7. 3*sizeof(float), // size of one vertex data
posVertexBuffer = HardwareBufferManager::getSingleton().createVertexBuffer(
3*sizeof(float), // size of one vertex data
numVertices, // number of vertices
HardwareBuffer::HBU_STATIC_WRITE_ONLY,
// the modification method of data
false // no shadow buffer );
normalVertexBuffer = …
texcoordsVertexBuffers = …
indexBuffer = HardwareBufferManager::getSingleton().createIndexBuffer(
HardwareIndexBuffer::IT_16BIT, // index type
mNumFaces*3, // total face number
HardwareBuffer::HBU_STATIC_WRITE_ONLY);
useShadowBuffer If set to true, this buffer will be 'shadowed' by one stored in
system memory rather than GPU or AGP memory. You should set this flag if you intend
to read data back from the vertex buffer, because reading data from a buffer
in the GPU or AGP memory is very expensive, and is in fact impossible if you
specify HBU_WRITE_ONLY for the main buffer. If you use this option, all
reads and writes will be done to the shadow buffer, and the shadow buffer will
be synchronised with the real buffer at an appropriate time

8. Set data of all buffer -1
// Lock the entire buffer for reading / writing
float *posBufData = (float*)postVertexBuffer->lock(HardwareBuffer::HBL_NORMAL);
posBufData[index] = x; …
// Releases the lock on this buffer
postVertexBuffer->unlock();
float *normalBufData = …
float *texcoordsBufData = …
float *indexBuffer = …

9. Set data of all buffer -2 float * _vertexBuf = new float[num];
_vertexBuf[index] = x; …
posVertexBuffer->writeData(
0, // offset
posVertexBuffer->getSizeInBytes(), // data size
_vertexBuf, // source buffer
true // discard? );
normalVertexBuffer->writeData(…)
texcoordsVertexBuffers->writeData(…)
indexBuffer->writeData(…)

10. Set vertex buffer bindings
VertexBufferBinding *vbind = subMesh->vertexData->vertexBufferBinding ;
vbind->setBinding(0, posVertexBuffer);
vbind->setBinding(1, normalVertexBuffer);
vbind->setBinding(2, texcoordsVertexBuffers);
// index, source buffer

11. Set vertex buffer declaration
VertexDeclaration *vdecl = subMesh->vertexData->vertexDeclaration;
vdecl->addElement(0, 0, VET_FLOAT3, VES_POSITION);
vdecl->addElement(1, 0, VET_FLOAT3, VES_NORMAL);
vdecl->addElement(2, 0, VET_FLOAT2, VES_TEXTURE_COORDINATES);
// index, initial location, component number, data type

12. Set index data subMesh->indexData->indexBuffer = indexBuffer;
subMesh->indexData->indexStart = 0;
subMesh->indexData->indexCount = mNumFaces*3;

13. Define the bound of the mesh
AxisAlignedBox bounds(mx, my, mz, Mx, My, Mz);
mesh->_setBounds(bounds);
mesh->load();
mesh->touch();
/** Loads the resource, if it is not already.
If the resource is loaded from a file, loading is automatic. If not,
if for example this resource gained it's data from procedural calls
rather than loading from a file, then this resource will not reload
on it's own. */
/** 'Touches' the resource to indicate it has been used.

14. How to use the mesh createMesh(“myMesh”);
Entity* en = mSceneMgr->createEntity(“en”, “myMesh”);
en->setMaterialName("Examples/GrassFloor");
SceneNode* sn = mSceneMgr->getRootSceneNode()->createChildSceneNode(“sn”);
sn->attachObject(en);

15. Create a mesh with ManualObject
// create the triangular face by using ManualObject
ManualObject* manual = mSceneMgr->createManualObject("triangle");
manual->begin(MaterialName, RenderOperation::OT_TRIANGLE_LIST);
manual->position(-100.0,  100.0, 0.0);
manual->position(-100.0, , 0.0);
manual->position( 100.0, , 0.0);
manual->end();
// attach the object to a scene node
SceneNode* sn = mSceneMgr->getRootSceneNode()->createChildSceneNode("SceneNode");
sn->attachObject(manual);

16. Convert Manual Object to mesh
MeshPtr mesh = manual->convertToMesh(strName);
AxisAlignedBox bounds = computeBounds();
mesh->_setBounds(bounds);
Then, we can use the mesh data repetitively.