Meshes. 9 th Week, To gain an understanding of the internal data organization of an ID3DXMesh object

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1 Meshes 9 th Week, 2009 Objectives To gain an understanding of the internal data organization of an ID3DXMesh object To find out how to create, optimize, i and render an ID3DXMesh object To learn how to load the data of an.x file into an ID3DXMesh object To become familiar with several D3DX meshrelated utility functions To learn about bounding volumes, why they are useful, and how to create them using the D3DX functions

2 Geometry Info (1) ID3DXMesh interface inherits the majority of the functionality from its parent, ID3DXBaseMesh ID3DXBaseMesh ID3DXMesh Getting a pointer to a vertex and an index buffers HRESULT ID3DXMesh::GetVertexBuffer(LPDIRECT3DVERTEXBUFFER9* ppvb); HRESULT ID3DXMesh::GetIndexBuffer(LPDIRECT3DINDEXBUFFER9* ppib); Ex) IDirect3DVertexBuffer9* vb = 0; Mesh->GetVertexBuffer( &vb ); IDirect3DIndexBuffer9* ib = 0; Mesh->GetIndexBuffer( &ib ); Geometry Info (2) ID3DXMesh interface (cont ) To lock / unlock the buffers to read or write to them HRESULT ID3DXMesh::LockVertexBuffer(DWORD Flags, BYTE** ppdata); HRESULT ID3DXMesh::LockIndexBuffer(DWORD Flags, BYTE** ppdata); HRESULT ID3DXMesh::UnlockVertexBuffer( ); HRESULT ID3DXMesh::UnlockIndexBuffer( ); To obtain geometry-related related information HRESULT ID3DXMesh::GetDeclaration( D3DVERTEXELEMENT9 Declaration[MAX_FVF_DECL_SIZE] ); DWORD ID3DXMesh::GetNumVertices( ); DWORD ID3DXMesh::GetNumBytesPerVertex( ); DWORD ID3DXMesh::GetNumFaces( );

3 MSDN ID3DXMesh Subsets and the Attribute Buffer (1) Subset a group of triangles in the mesh that can all be rendered using the same attribute Attribute t material, texture, t and render state t Subset 2: Window Render triangles in subset using window attributes Subset 0: Body Render triangles in subset using body attributes Subset 1: Tires Render triangles in subset using tire attributes Subset 3: Lights Render triangles in subset using light attributes < A car broken up by subsets >

4 Subsets and the Attribute Buffer (2) Attribute ID a unique positive integer value for each subset Each triangle in the mesh is given an attribute ID Attribute buffer a DWORD array to store the attribute t IDs for the triangles # of elements in attribute buffer == # of faces Attribute Buffer Triangle 0 Triangle 1 Triangle n Index Buffer Subsets and the Attribute Buffer (3) One-to-one correspondence Entry i in the attribute buffer corresponds with triangle i in the index buffer Three indices in the index buffer of triangle i A = i 33 B = i 3+ 1 C = i Access to the attribute buffer by locking it DWORD *buffer = 0; Mesh->LockAttributeBuffer(lockingFlags, &buffer); // Read or write to attribute buffer... Mesh->UnlockAttributeBuffer( );

5 Drawing Drawing the triangles of a particular subset specified by the AttribId argument HRESULT ID3DXMesh::DrawSubset(DWORD AttribId); Ex) to draw all the triangles that live in subset 0 Mesh->DrawSubset(0); Ex) to draw an entire mesh HR(mFX->BeginPass(0)); for(int j=0; j<mmtrl.size(); j++) { HR(mFX->SetValue(mhMtrl, &mmtrl[j], sizeof(mtrl))); if(mtex[j]!= 0 ) HR(mFX->SetTexture(mhTex, ( mtex[j])); else HR(mFX->SetTexture(mHTex, mwhitetex)); HR(mFX->CommitChanges()); HR(mMesh->DrawSubset(j)); } HR(mFX->EndPass()); Adjacency Info (1) For certain mesh operations, such as optimizing Adjacency array Triangles that are adjacent to a given triangle DWORD array where each entry contains an index identifying a triangle in the mesh Tri 2 Tri 1 Adjacency Array Tri 0 Index Buffer Tri 0 Tri 1 Tri 2

6 Adjacency Info (2) Adjacency array (cont ) An entry i refers to the triangle formed by indices: A = i 33 B = i C = i Particular edge does not have an adjacent triangle ULONG_MAX == 4,294,967, == 1 (DWORD: unsigned 32-bit integer) Must have (ID3DXBASEMESH::GetNumFaces( () * 3) elements Adjacency Info (3) Outputting the adjacency info HRESULT ID3DXMesh::GenerateAdjacency ( FLOAT fepsilon, DWORD* padjacency ); fepsilon value specifying how far two vertices can differ in position and still be considered equal padjacency a pointer to an array of DWORDs that is to be filled with the adjacency info Ex) DWORD *adjacencyinfo = new DWORD[Mesh->GetNumFaces()*3]; Ex) DWORD adjacencyinfo new DWORD[Mesh >GetNumFaces() 3]; Mesh->GenerateAdjacency( 0.001f, adjacencyinfo );

7 Optimizing (1) Reorganizing the vertices and indices of a mesh to render the mesh more efficiently Flags: HRESULT ID3DXMesh::Optimize ( DWORD Flags, CONST DWORD *padjacencyin, DWORD *padjacencyout, DWORD *pfaceremap, LPD3DXBUFFER *ppvertexremap, LPD3DXMESH *ppoptmesh ); D3DXMESHOPT_COMPACT, D3DXMESHOPT_ATTRSORT, D3DXMESHOPT_VERTEXCACHE, D3DXMESHOPT_STRIPREORDER, D3DXMESHOPT_IGNOREVERTS, D3DXMESHOPT_DONOTSPLITDONOTSPLIT D3DXMESH_SYSTEMMEM, D3DXMESH_MANAGED, D3DXMESH_DYNAMIC Optimizing (2) padjacencyin: the adjacency info of the mesh object invoking this method padjacencyout: a DWORD array to be filled with adjacency info of the optimized mesh pfaceremap: a DWORD array to be filled with the face remap info ppvertexremap: an ID3DXBuffer that will be filled with the vertex remap info ppoptmesh: the optimized mesh

8 Optimizing (3) Ex) // Get the adjacency info of the non-optimized mesh. DWORD *adjacencyinfo = new DWORD[Mesh->GetNumFaces()*3]; Mesh->GenerateAdjacency( 0.0f, 0 adjacencyinfo ); // Array to hold optimized adjacency info. DWORD *optimizedadjacencyinfo = new DWORD[Mesh->GetNumFaces()*3]; ID3DXMesh *meshout = 0; HR(Mesh->Optimize( D3DXMESH_MANAGED D3DXMESHOPT_COMPACT C D3DXMESHOPT_ATTRSORT D3DXMESHOPT_VERTEXCACHE, adjacencyinfo, optimizedadjacencyinfo, 0, 0, &meshout)); Optimizing (4) Similar method which actually optimizes the calling mesh object instead of outputting an optimized mesh HRESULT ID3DXMesh::OptimizeInplace ( DWORD Flags, CONST DWORD *padjacencyin, DWORD *padjacencyout, DWORD *pfaceremap, LPD3DXBUFFER *ppvertexremap );

9 The Attribute Table (1) Sorting the geometry of a mesh by its attribute Optimizing a mesh with the D3DXMESHOPT_ATTRSORT flag Subset 0 Subset 1 Subset 2 Attribute Buffer Index Buffer Tri 0 Tri 1 Tri 2 Tri 3 Tri 4 Tri 5 Tri 6 Tri 7 Tri 8 Tri 9 Start Start Start Count Count Count The Attribute Table (2) An array of D3DXATTRIBUTERANGE structure Each entry corresponds to a subset of the mesh typedef struct _D3DXATTRIBUTERANGE { DWORD AttribId; DWORD FaceStart; DWORD FaceCount; DWORD VertexStart; t DWORD VertexCount; } D3DXATTRIBUTERANGE; Rendering a subset very efficiently!! AttribId: thesubsetid FaceStart: an offset into the index buffer (FaceStart * 3) identifying the start of the triangles FaceCount: the number of faces (triangles) VertexStart: an offset into the vertex buffer identifying the start of the vertices VertexCount: the number of vertices

10 The Attribute Table (3) Access to the attribute table of a mesh Two things: returning the number of attributes in the attribute table and filling the attribute table HRESULT ID3DXMesh::GetAttributeTable ( D3DXATTRIBUTERANGE* pattribtable, DWORD* pattribtablesize ); Ex1) to get the number of elements in the attribute table DWORD numsubsets = 0; Mesh->GetAttributeTable( 0, &numsubsets ); D3DXATTRIBUTERANGE table = new D3DXATTRIBUTERANGE[numSubsets]; Mesh->GetAttributeTable( table, &numsubsets ); Ex2) to directly set the attribute table D3DXATTRIBUTERANGE attributetable[12]; // fill attributetable array with data... Mesh->SetAttributeTable( attributetable, 12 ); Cloning (1) Copying the data from one mesh to another HRESULT ID3DXMesh::CloneMesh ( DWORD Options, const D3DVERTEXELEMENT9 *pdeclaration, LPDIRECT3DDEVICE9 pdevice, LPD3DXMESH *ppclonemesh ); Options: D3DXMESH_32BIT, D3DXMESH_SYSTEMMEM, D3DXMESH_MANAGED, MANAGED D3DXMESH_WRITEONLY, D3DXMESH_DYNAMIC pdeclaration: the vertex format we want for the new cloned mesh pdevice: the device ppclonedmesh: the cloned mesh

11 MSDN D3DXMESH Flags Cloning (2) Useful if the options or vertex format need to changing when copying a mesh Ex) D3DVERTEXELEMENT9 elements[] = { {0,0,D3DDECLTYPE_FLOAT3,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_POSITION,0}, {0,12,D3DDECLTYPE_FLOAT3,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_NORMAL,0}, D3DDECLMETHOD DEFAULT D3DDECLUSAGE 0} {0,24,D3DDECLTYPE_FLOAT2,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_TEXCOORD,0}, D3DDECL_END() }; // Assume meshsys is of type ID3DXMesh*. ID3DXMesh* temp = 0; HR(meshSys->CloneMesh( D3DXMESH_SYSTEMMEM, SYSTEMMEM elements, gd3ddevice, &temp));

12 Creating a Mesh (D3DXCreateMesh) (1) Creating an empty mesh Specifying the number of faces and vertices (of some specified format) D3DXCreateMesh allocates the appropriately sized vertex, index, and attribute buffers Manually filling in the mesh s data contents HRESULT ID3DXCreateMesh ( DWORD NumFaces, DWORD NumVertices, DWORD Options, CONST LPD3DVERTEXELEMENT9 *pdeclaration, LPDIRECT3DDEVICE9 pdevice, LPD3DXMESH *ppmesh ); Creating a Mesh (D3DXCreateMesh) (2) Creating an empty mesh (cont ) NumFaces: the number of faces NumVertices: the number of vertices Options: D3DXMESH_32BIT, 32BIT D3DXMESH_SYSTEMMEM, SYSTEMMEM D3DXMESH_MANAGED, D3DXMESH_WRITEONLY, D3DXMESH_DYNAMIC pdeclaration: the vertex format of the mesh vertices pdevice: the device ppmesh: the created mesh

13 Creating a Mesh (D3DXCreateMesh) (3) Ex) D3DVERTEXELEMENT9 elements[] = { {0,0,D3DDECLTYPE_FLOAT3,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_POSITION,0}, {0,12,D3DDECLTYPE_FLOAT3,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_NORMAL,0}, D3DDECLMETHOD DEFAULT D3DDECLUSAGE 0} {0,24,D3DDECLTYPE_FLOAT2,D3DDECLMETHOD_DEFAULT,D3DDECLUSAGE_TEXCOORD,0}, D3DDECL_END() }; ID3DXMesh* mesh = 0; HR(D3DXCreateMesh( 12, 24, D3DXMESH_MANAGED, elements, gd3ddevice, &mesh )); 3D modelers.x Files To build complex and realistic meshes in a visual and interactive environment with a rich toolset Ex) 3D Studio MAX ( LightWave 3D ( Maya ( and Softimage XSI ( Converters To export the created mesh data (geometry, materials, animations, and other possible useful data) to.x files Ex) PolyTrans ( Deep Exploration ( dexp)

14 .X File Demo Loading an.x File (1)

15 Loading an.x File (2) Loading an.x File (3) void LoadXFile( const std::string& filename, ID3DXMesh** meshout, std::vector<mtrl>& mtrls, std::vector<idirect3dtexture9*>& texs); filename:.x file meshout: the newly created mesh mtrls: the materials of the mesh texs: the textures of the mesh

16 Loading an.x File (4) Loading an.x File (5) HRESULT D3DXLoadMeshFromX ( LPCSTR pfilename, DWORD Options, LPDIRECT3DDEVICE9 pdevice, LPD3DXBUFFER *ppadjacency, LPD3DXBUFFER *ppmaterials, LPD3DXBUFFER *ppeffectinstances, PDWORD pnummaterials, LPD3DXMESH *ppmesh ); filename:.x file Options: D3DXMESH 32BIT D3DXMESH SYSTEMMEM D3DXMESH_32BIT, D3DXMESH_SYSTEMMEM, D3DXMESH_MANAGED, D3DXMESH_WRITEONLY, D3DXMESH_DYNAMIC pdevice: the device

17 Loading an.x File (6) ppadjacency: the adjacency info of the mesh ppmaterials: the material data of the mesh ppeffectinstances: one effect instance per subset to store an.fx filename and the data needed to initialize the effect parameters (in this book,.x files do not carry effect information) pnummaterials: the number of materials for the mesh ppmesh: the created ID3DXMesh object Testing for Vertex Normals

18 Changing the Vertex Format Generating Normals

19 Optimizing.X File Materials (1)

20 .X File Materials (2) Number of materials the mesh contains Argument seven of D3DXLoadMeshFromX function Array of D3DXMATERIAL structures containing the material data Argument five of D3DXLoadMeshFromX function typedef struct D3DXMATERIAL { D3DMATERIAL9 MatD3D; LPSTR ptexturefilename; } D3DXMATERIAL; typedef struct _D3DMATERIAL9 { D3DCOLORVALUE Diffuse; D3DCOLORVALUE Ambient; D3DCOLORVALUE Specular; D3DCOLORVALUE Emissive; float Power; } D3DMATERIAL9;.X File Materials (3).X File doesn t embed the texture data After loading an.x file, the texture data must be loaded given the texture filenames The ith entry in the returned D3DMATERIAL array corresponds with the ith subset The subsets are labeled in the order 0, 1, 2,, n 1

21 New Structures Member Variables

22 Constructor Destructor

23 Rendering Bounding Volumes (1) Common example spheres and axis-aligned bounding boxes (AABB) Others: cylinders, ellipsoids, lozenges, capsules max radius center min To speed up visibility tests and collision tests

24 Bounding Volumes (2) D3DX library provides functions HRESULT D3DXComputeBoundingSphere ( LPD3DXVECTOR3 pfirstposition, DWORD NumVertices, DWORD dwstride, D3DXVECTOR3* pcenter, FLOAT* pradius ); pfirstposition: the position element in the first vertex of an array of vertices NumVertices: the number of vertices dwstride: the size of each vertex in bytes pcenter: the center of the bounding sphere pradius: the radius of the bounding sphere Bounding Volumes (3) D3DX library provides functions (cont ) HRESULT D3DXComputeBoundingBox ( LPD3DXVECTOR3 pfirstposition, DWORD NumVertices, DWORD dwstride, D3DXVECTOR3* pmin, D3DXVECTOR3* pmax ); pfirstposition: the position element in the first vertex of an array of vertices NumVertices: the number of vertices dwstride: the size of each vertex in bytes pmin: the AABB s minimum point pmax: the AABB s maximum point

25 Bounding Box Demo Some New Special Constants

26 Bounding Volume Types Member Variables

27 Constructor Destructor

28 Rendering Exercises Rewrite the Bounding Box demo, but this time, compute the bounding sphere and render it along with the mesh

Meshes Part II. June 13, 2005

Meshes Part II. June 13, 2005 Game Programming Meshes Part II June 13, 2005 Objectives To learn how to load the data of an XFile into an ID3DXMesh object To gain an understanding of the benefits of using progressive meshes and how