source: downloads/Samples/DeferredShading/include/CreateSphere.h @ 3

/// From the WIKI -- tesselate a sphere
void createSphere(const std::string& strName, const float r, const int nRings = 16, const int nSegments = 16)
{
        MeshPtr pSphere = MeshManager::getSingleton().createManual(strName, ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME);
        SubMesh *pSphereVertex = pSphere->createSubMesh();

        pSphere->sharedVertexData = new VertexData();
        VertexData* vertexData = pSphere->sharedVertexData;

        // define the vertex format
        VertexDeclaration* vertexDecl = vertexData->vertexDeclaration;
        size_t currOffset = 0;
        // positions
        vertexDecl->addElement(0, currOffset, VET_FLOAT3, VES_POSITION);
        currOffset += VertexElement::getTypeSize(VET_FLOAT3);
        // normals
        vertexDecl->addElement(0, currOffset, VET_FLOAT3, VES_NORMAL);
        currOffset += VertexElement::getTypeSize(VET_FLOAT3);
        // two dimensional texture coordinates
        vertexDecl->addElement(0, currOffset, VET_FLOAT2, VES_TEXTURE_COORDINATES, 0);
        currOffset += VertexElement::getTypeSize(VET_FLOAT2);

        // allocate the vertex buffer
        vertexData->vertexCount = (nRings + 1) * (nSegments+1);
        HardwareVertexBufferSharedPtr vBuf = HardwareBufferManager::getSingleton().createVertexBuffer(vertexDecl->getVertexSize(0), vertexData->vertexCount, HardwareBuffer::HBU_STATIC_WRITE_ONLY, false);
        VertexBufferBinding* binding = vertexData->vertexBufferBinding;
        binding->setBinding(0, vBuf);
        float* pVertex = static_cast<float*>(vBuf->lock(HardwareBuffer::HBL_DISCARD));

        // allocate index buffer
        pSphereVertex->indexData->indexCount = 6 * nRings * (nSegments + 1);
        pSphereVertex->indexData->indexBuffer = HardwareBufferManager::getSingleton().createIndexBuffer(HardwareIndexBuffer::IT_16BIT, pSphereVertex->indexData->indexCount, HardwareBuffer::HBU_STATIC_WRITE_ONLY, false);
        HardwareIndexBufferSharedPtr iBuf = pSphereVertex->indexData->indexBuffer;
        unsigned short* pIndices = static_cast<unsigned short*>(iBuf->lock(HardwareBuffer::HBL_DISCARD));

        float fDeltaRingAngle = (Math::PI / nRings);
        float fDeltaSegAngle = (2 * Math::PI / nSegments);
        unsigned short wVerticeIndex = 0 ;

        // Generate the group of rings for the sphere
        for( int ring = 0; ring <= nRings; ring++ ) {
                float r0 = r * sinf (ring * fDeltaRingAngle);
                float y0 = r * cosf (ring * fDeltaRingAngle);

                // Generate the group of segments for the current ring
                for(int seg = 0; seg <= nSegments; seg++) {
                        float x0 = r0 * sinf(seg * fDeltaSegAngle);
                        float z0 = r0 * cosf(seg * fDeltaSegAngle);

                        // Add one vertex to the strip which makes up the sphere
                        *pVertex++ = x0;
                        *pVertex++ = y0;
                        *pVertex++ = z0;

                        Vector3 vNormal = Vector3(x0, y0, z0).normalisedCopy();
                        *pVertex++ = vNormal.x;
                        *pVertex++ = vNormal.y;
                        *pVertex++ = vNormal.z;

                        *pVertex++ = (float) seg / (float) nSegments;
                        *pVertex++ = (float) ring / (float) nRings;

                        if (ring != nRings) {
                               // each vertex (except the last) has six indicies pointing to it
                                *pIndices++ = wVerticeIndex + nSegments + 1;
                                *pIndices++ = wVerticeIndex;               
                                *pIndices++ = wVerticeIndex + nSegments;
                                *pIndices++ = wVerticeIndex + nSegments + 1;
                                *pIndices++ = wVerticeIndex + 1;
                                *pIndices++ = wVerticeIndex;
                                wVerticeIndex ++;
                        }
                }; // end for seg
        } // end for ring

        // Unlock
        vBuf->unlock();
        iBuf->unlock();
        // Generate face list
        pSphereVertex->useSharedVertices = true;

        // the original code was missing this line:
        pSphere->_setBounds( AxisAlignedBox( Vector3(-r, -r, -r), Vector3(r, r, r) ), false );
        pSphere->_setBoundingSphereRadius(r);
        // this line makes clear the mesh is loaded (avoids memory leakes)
        pSphere->load();
}