OGRE片段教程——创建mesh

原文地址：http://wiki.ogre3d.org/Generating+A+Mesh

下面是创建一个mesh的方法，mesh的名称为 "ColourCube"，它包含一个submesh

void createColourCube()
{
    /// 通过MeshManager创建mesh
    Ogre::MeshPtr msh = MeshManager::getSingleton().createManual("ColourCube", "General");

    /// 创建一个submesh
    SubMesh* sub = msh->createSubMesh();

    const float sqrt13 = 0.577350269f; /* sqrt(1/3) */

    /// 定义顶点 (8个顶点,每个顶点有3个float变量，代表位置；3个float变量代表法线)
    const size_t nVertices = 8;
    const size_t vbufCount = 3*2*nVertices;
    float vertices[vbufCount] = {
            -100.0,100.0,-100.0,        //0 position
            -sqrt13,sqrt13,-sqrt13,     //0 normal
            100.0,100.0,-100.0,         //1 position
            sqrt13,sqrt13,-sqrt13,      //1 normal
            100.0,-100.0,-100.0,        //2 position
            sqrt13,-sqrt13,-sqrt13,     //2 normal
            -100.0,-100.0,-100.0,       //3 position
            -sqrt13,-sqrt13,-sqrt13,    //3 normal
            -100.0,100.0,100.0,         //4 position
            -sqrt13,sqrt13,sqrt13,      //4 normal
            100.0,100.0,100.0,          //5 position
            sqrt13,sqrt13,sqrt13,       //5 normal
            100.0,-100.0,100.0,         //6 position
            sqrt13,-sqrt13,sqrt13,      //6 normal
            -100.0,-100.0,100.0,        //7 position
            -sqrt13,-sqrt13,sqrt13,     //7 normal
    };

    RenderSystem* rs = Root::getSingleton().getRenderSystem();
    RGBA colours[nVertices];
    RGBA *pColour = colours;
    // Use render system to convert colour value since colour packing varies
    rs->convertColourValue(ColourValue(1.0,0.0,0.0), pColour++); //0 colour
    rs->convertColourValue(ColourValue(1.0,1.0,0.0), pColour++); //1 colour
    rs->convertColourValue(ColourValue(0.0,1.0,0.0), pColour++); //2 colour
    rs->convertColourValue(ColourValue(0.0,0.0,0.0), pColour++); //3 colour
    rs->convertColourValue(ColourValue(1.0,0.0,1.0), pColour++); //4 colour
    rs->convertColourValue(ColourValue(1.0,1.0,1.0), pColour++); //5 colour
    rs->convertColourValue(ColourValue(0.0,1.0,1.0), pColour++); //6 colour
    rs->convertColourValue(ColourValue(0.0,0.0,1.0), pColour++); //7 colour

    /// 定义12个三角面索引 (每个面有两个三角形)
    /// 索引值指向上边的顶点类表
    const size_t ibufCount = 36;
    unsigned short faces[ibufCount] = {
            0,2,3,
            0,1,2,
            1,6,2,
            1,5,6,
            4,6,5,
            4,7,6,
            0,7,4,
            0,3,7,
            0,5,1,
            0,4,5,
            2,7,3,
            2,6,7
    };

    /// 创建顶点数据结构 Create vertex data structure for 8 vertices shared between submeshes
    msh->sharedVertexData = new VertexData();
    msh->sharedVertexData->vertexCount = nVertices;

    /// 创建格式定义（存储格式）Create declaration (memory format) of vertex data
    VertexDeclaration* decl = msh->sharedVertexData->vertexDeclaration;
    size_t offset = 0;
    // 第一层缓冲区
    decl->addElement(0, offset, VET_FLOAT3, VES_POSITION);
    offset += VertexElement::getTypeSize(VET_FLOAT3);
    decl->addElement(0, offset, VET_FLOAT3, VES_NORMAL);
    offset += VertexElement::getTypeSize(VET_FLOAT3);
    /// 分配顶点缓冲 Allocate vertex buffer of the requested number of vertices (vertexCount) 
    /// and bytes per vertex (offset)
    HardwareVertexBufferSharedPtr vbuf = 
        HardwareBufferManager::getSingleton().createVertexBuffer(
        offset, msh->sharedVertexData->vertexCount, HardwareBuffer::HBU_STATIC_WRITE_ONLY);
    /// 将顶点数据写入
    vbuf->writeData(0, vbuf->getSizeInBytes(), vertices, true);

    /// 将顶点缓冲绑定Set vertex buffer binding so buffer 0 is bound to our vertex buffer
    VertexBufferBinding* bind = msh->sharedVertexData->vertexBufferBinding; 
    bind->setBinding(0, vbuf);

    // 第二次缓冲区
    offset = 0;
    decl->addElement(1, offset, VET_COLOUR, VES_DIFFUSE);
    offset += VertexElement::getTypeSize(VET_COLOUR);
    /// 分配缓冲区 Allocate vertex buffer of the requested number of vertices (vertexCount) 
    /// and bytes per vertex (offset)
    vbuf = HardwareBufferManager::getSingleton().createVertexBuffer(
        offset, msh->sharedVertexData->vertexCount, HardwareBuffer::HBU_STATIC_WRITE_ONLY);
    ///将输入些人
    vbuf->writeData(0, vbuf->getSizeInBytes(), colours, true);

    /// 将颜色数据写入 Set vertex buffer binding so buffer 1 is bound to our colour buffer
    bind->setBinding(1, vbuf);

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

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

    ///设置submesn参数 Set parameters of the submesh

   sub->useSharedVertices = true;

sub->indexData->indexBuffer = ibuf;//索引

   sub->indexData->indexCount = ibufCount;//索引个数 

 sub->indexData->indexStart = 0; 

 /// 设置包围合 Set bounding information (for culling) 

msh->_setBounds(AxisAlignedBox(-100,-100,-100,100,100,100));

mesh->_setBoundingSphereRadius(Math::Sqrt(3*100*100)); 

 ///通知mesh加载 

 msh->load();}

定义材质:

material Test/ColourTest
{
    technique
    {
        pass
        {
            ambient vertexcolour
        }
    }
}

或者,材质可以直接用C++程序创建:

MaterialPtr material = MaterialManager::getSingleton().create(
      "Test/ColourTest", ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME);
material->getTechnique(0)->getPass(0)->setVertexColourTracking(TVC_AMBIENT);

将mesh加入到场景中:

Entity* thisEntity = mSceneMgr->createEntity("cc", "ColourCube");
thisEntity->setMaterialName("Test/ColourTest");
SceneNode* thisSceneNode = mSceneMgr->getRootSceneNode()->createChildSceneNode();
thisSceneNode->setPosition(-35, 0, 0);
thisSceneNode->attachObject(thisEntity);