公告板(billboard)是一种允许在2D对象出现在3D中的很酷的技术，公告板的原理就是通过使用世界矩阵，根据观察点来排列多边形，因为观察的角度已知（或能够获得一个观察变换矩阵），就只需要使用相反的观察角来构造矩阵。创建公告板世界矩阵的方法是从Direct3D获取当前的观察矩阵并将此矩阵转置。这个转置矩阵会将所有的东西进行恰当的定位，以朝向观察点。接着就只需应用网格的平移矩阵，在世界中正确地确定网格的位置。
源码中的Setup_Mesh函数用来创建顶点缓冲和从文件取得纹理数据，其中用到了D3DXCreateTextureFromFileEx函数，来看看它的使用信息：
Creates a texture from a file. This is a more advanced function than D3DXCreateTextureFromFile.
Syntax
HRESULT WINAPI D3DXCreateTextureFromFileEx(LPDIRECT3DDEVICE9 pDevice,
LPCTSTR pSrcFile,
UINT Width,
UINT Height,
UINT MipLevels,
DWORD Usage,
D3DFORMAT Format,
D3DPOOL Pool,
DWORD Filter,
DWORD MipFilter,
D3DCOLOR ColorKey,
D3DXIMAGE_INFO *pSrcInfo,
PALETTEENTRY *pPalette,
LPDIRECT3DTEXTURE9 *ppTexture
);
Parameters
pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device to be associated with the texture.
pSrcFile
[in] Pointer to a string that specifies the filename. If the compiler settings require Unicode, the data type LPCTSTR resolves to LPCWSTR. Otherwise, the string data type resolves to LPCSTR. See Remarks.
Width
[in] Width in pixels. If this value is zero or D3DX_DEFAULT, the dimensions are taken from the file and rounded up to a power of two. If the device supports non-power of 2 textures and D3DX_DEFAULT_NONPOW2 is specified, the size will not be rounded.
Height
[in] Height, in pixels. If this value is zero or D3DX_DEFAULT, the dimensions are taken from the file and rounded up to a power of two. If the device supports non-power of 2 textures and D3DX_DEFAULT_NONPOW2 is sepcified, the size will not be rounded.
MipLevels
[in] Number of mip levels requested. If this value is zero or D3DX_DEFAULT, a complete mipmap chain is created. If D3DX_FROM_FILE, the size will be taken exactly as it is in the file, and the call will fail if this violates device capabilities.
Usage
[in] 0, D3DUSAGE_RENDERTARGET, or D3DUSAGE_DYNAMIC. Setting this flag to D3DUSAGE_RENDERTARGET indicates that the surface is to be used as a render target. The resource can then be passed to the pNewRenderTarget parameter of the IDirect3DDevice9::SetRenderTarget method. If either D3DUSAGE_RENDERTARGET or D3DUSAGE_DYNAMIC is specified, Pool must be set to D3DPOOL_DEFAULT, and the application should check that the device supports this operation by calling IDirect3D9::CheckDeviceFormat. D3DUSAGE_DYNAMIC indicates that the surface should be handled dynamically. See Using Dynamic Textures.
Format
[in] Member of the D3DFORMAT enumerated type, describing the requested pixel format for the texture. The returned texture might have a different format from that specified by Format. Applications should check the format of the returned texture. If D3DFMT_UNKNOWN, the format is taken from the file. If D3DFMT_FROM_FILE, the format is taken exactly as it is in the file, and the call will fail if this violates device capabilities.
Pool
[in] Member of the D3DPOOL enumerated type, describing the memory class into which the texture should be placed.
Filter
[in] A combination of one or more D3DX_FILTER controlling how the image is filtered. Specifying D3DX_DEFAULT for this parameter is the equivalent of specifying D3DX_FILTER_TRIANGLE | D3DX_FILTER_DITHER.
MipFilter
[in] A combination of one or more D3DX_FILTER controlling how the image is filtered. Specifying D3DX_DEFAULT for this parameter is the equivalent of specifying D3DX_FILTER_BOX.
ColorKey
[in] D3DCOLOR value to replace with transparent black, or 0 to disable the color key. This is always a 32-bit ARGB color, independent of the source image format. Alpha is significant and should usually be set to FF for opaque color keys. Thus, for opaque black, the value would be equal to 0xFF000000.
pSrcInfo
[in, out] Pointer to a D3DXIMAGE_INFO structure to be filled in with a description of the data in the source image file, or NULL.
pPalette
[out] Pointer to a PALETTEENTRY structure, representing a 256-color palette to fill in, or NULL.
ppTexture
[out] Address of a pointer to an IDirect3DTexture9 interface, representing the created texture object.
Return Value
If the function succeeds, the return value is D3D_OK.
If the function fails, the return value can be one of the following:
D3DERR_INVALIDCALL The method call is invalid. For example, a method's parameter may have an invalid value.
D3DERR_NOTAVAILABLE This device does not support the queried technique.
D3DERR_OUTOFVIDEOMEMORY Direct3D does not have enough display memory to perform the operation.
D3DXERR_INVALIDDATA The data is invalid.
E_OUTOFMEMORY Direct3D could not allocate sufficient memory to complete the call.
Remarks
The compiler setting also determines the function version. If Unicode is defined, the function call resolves to D3DXCreateTextureFromFileExW. Otherwise, the function call resolves to D3DXCreateTextureFromFileExA because ANSI strings are being used.
Use D3DXCheckTextureRequirements to determine if your device can support the texture given the current state.
This function supports the following file formats: .bmp, .dds, .dib, .hdr, .jpg, .pfm, .png, .ppm, and .tga. See D3DXIMAGE_FILEFORMAT.
Mipmapped textures automatically have each level filled with the loaded texture. When loading images into mipmapped textures, some devices are unable to go to a 1x1 image and this function will fail. If this happens, then the images need to be loaded manually.
For the best performance when using D3DXCreateTextureFromFileEx:
Doing image scaling and format conversion at load time can be slow. Store images in the format and resolution they will be used. If the target hardware requires power of 2 dimensions, then create and store images using power of 2 dimensions.
For mipmap image creation at load time, filter using D3DX_FILTER_BOX. A box filter is much faster than other filter types such as D3DX_FILTER_TRIANGLE.
Consider using DDS files. Since DDS files can be used to represent any Microsoft DirectX 9.0 texture format, they are very easy for D3DX to read. Also, they can store mipmaps, so any mipmap-generation algorithms can be used to author the images.
我们来看看Do_Frame是如何进行公告板的绘制的，以下是关键代码：
// build view matrix
D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
&D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));
// set view matrix
g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);
// Begin scene
if(SUCCEEDED(g_d3d_device->BeginScene()))
{
// 1) draw the floor
// binds a vertex buffer to a device data stream
g_d3d_device->SetStreamSource(0, g_floor_vb, 0, sizeof(VERTEX));
// set the current vertex stream declation
g_d3d_device->SetFVF(VERTEX_FVF);
// assigns a texture to a stage for a device
g_d3d_device->SetTexture(0, g_floor_texture);
// build world matrix, we only need identity matrix, because we do not need to change original floor position.
D3DXMatrixIdentity(&mat_world);
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// renders a sequence of noindexed, geometric primitives of the specified type from the current set
// of data input stream.
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
// 2) draw the billboards
g_d3d_device->SetStreamSource(0, g_billboard_vb, 0, sizeof(VERTEX));
g_d3d_device->SetTexture(0, g_billboard_texture);
// enable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
// get world matrix, just get it from view matrix's transpose.
D3DXMatrixTranspose(&mat_world, &mat_view);
// draw all billboard images
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
// disable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
// release texture
g_d3d_device->SetTexture(0, NULL);
// end the scene
g_d3d_device->EndScene();
}
D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
&D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));
// set view matrix
g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);
// Begin scene
if(SUCCEEDED(g_d3d_device->BeginScene()))
{
// 1) draw the floor
// binds a vertex buffer to a device data stream
g_d3d_device->SetStreamSource(0, g_floor_vb, 0, sizeof(VERTEX));
// set the current vertex stream declation
g_d3d_device->SetFVF(VERTEX_FVF);
// assigns a texture to a stage for a device
g_d3d_device->SetTexture(0, g_floor_texture);
// build world matrix, we only need identity matrix, because we do not need to change original floor position.
D3DXMatrixIdentity(&mat_world);
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// renders a sequence of noindexed, geometric primitives of the specified type from the current set
// of data input stream.
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
// 2) draw the billboards
g_d3d_device->SetStreamSource(0, g_billboard_vb, 0, sizeof(VERTEX));
g_d3d_device->SetTexture(0, g_billboard_texture);
// enable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
// get world matrix, just get it from view matrix's transpose.
D3DXMatrixTranspose(&mat_world, &mat_view);
// draw all billboard images
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
// disable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
// release texture
g_d3d_device->SetTexture(0, NULL);
// end the scene
g_d3d_device->EndScene();
}
1）地板的绘制：首先调用D3DXMatrixLookAtLH取得视口矩阵，接着调用SetTransform设置视口矩阵。绘制地板时先调用SetStreamSource和SetFVF设置顶点信息，再调用SetTexture设置纹理，接着调用D3DXMatrixIdentity单位化世界矩阵并设置世界矩阵，因为我们不需要改变地板的位置，所以世界矩阵直接设置为单位矩阵就可以了；再接着调用DrawPrimitive绘制图形。
2）公告板的绘制：首先设置顶点数据格式，接着启用alpha测试，再接着将视口矩阵转置得到世界矩阵，使用两层for循环来平移世界矩阵并设置世界矩阵，最后绘制这些公告板。
// draw all billboard images
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
完整源码如下:
/***************************************************************************************
PURPOSE:
Billboard Demo
Required libraries:
WINMM.lib, D3D9.LIB, D3DX9.LIB.
***************************************************************************************/
#include <windows.h>
#include <stdio.h>
#include "d3d9.h"
#include "d3dx9.h"
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "d3d9.lib")
#pragma comment(lib, "d3dx9.lib")
#pragma warning(disable : 4305 4244)
#define WINDOW_WIDTH 400
#define WINDOW_HEIGHT 400
#define Safe_Release(p) if((p)) (p)->Release();
// window handles, class and caption text.
HWND g_hwnd;
HINSTANCE g_inst;
static char g_class_name[] = "BillboardClass";
static char g_caption[] = "Billboard Demo";
// the Direct3D and device object
IDirect3D9* g_d3d = NULL;
IDirect3DDevice9* g_d3d_device = NULL;
// The 3D vertex format and descriptor
typedef struct
{
float x, y, z; // 3D coordinates
float u, v; // texture coordinates
} VERTEX;
#define VERTEX_FVF (D3DFVF_XYZ | D3DFVF_TEX1)
// the billboard vertex buffer and texture
IDirect3DVertexBuffer9* g_billboard_vb = NULL;
IDirect3DTexture9* g_billboard_texture = NULL;
// the floor vertex buffer and texture
IDirect3DVertexBuffer9* g_floor_vb = NULL;
IDirect3DTexture9* g_floor_texture = NULL;
//--------------------------------------------------------------------------------
// Window procedure.
//--------------------------------------------------------------------------------
long WINAPI Window_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return (long) DefWindowProc(hwnd, msg, wParam, lParam);
}
//--------------------------------------------------------------------------------
// Copy vertex data into vertex buffer, create texture from file.
//--------------------------------------------------------------------------------
BOOL Setup_Mesh()
{
BYTE* vertex_ptr;
VERTEX billboard_verts[] = {
{ -42.0f, 80.0f, 0.0f, 0.0f, 0.0f },
{ 40.0f, 80.0f, 0.0f, 1.0f, 0.0f },
{ -40.0f, 0.0f, 0.0f, 0.0f, 1.0f },
{ 40.0f, 0.0f, 0.0f, 1.0f, 1.0f }
};
VERTEX floor_verts[] = {
{ -100.0f, 0.0f, 100.0f, 0.0f, 0.0f },
{ 100.0f, 0.0f, 100.0f, 1.0f, 0.0f },
{ -100.0f, 0.0f, -100.0f, 0.0f, 1.0f },
{ 100.0f, 0.0f, -100.0f, 1.0f, 1.0f }
};
// create vertex buffers and stuff in data
// for billboard
if(FAILED(g_d3d_device->CreateVertexBuffer(sizeof(billboard_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT,
&g_billboard_vb, NULL)))
return FALSE;
// locks a range of vertex data and obtains a pointer to the vertex buffer memory
if(FAILED(g_billboard_vb->Lock(0, 0, (void**)&vertex_ptr, 0)))
return FALSE;
memcpy(vertex_ptr, billboard_verts, sizeof(billboard_verts));
// unlocks vertex data
g_billboard_vb->Unlock();
// for floor
if(FAILED(g_d3d_device->CreateVertexBuffer(sizeof(floor_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT, &g_floor_vb, NULL)))
return FALSE;
// locks a range of vertex data and obtains a pointer to the vertex buffer memory
if(FAILED(g_floor_vb->Lock(0, 0, (void**)&vertex_ptr, 0)))
return FALSE;
memcpy(vertex_ptr, floor_verts, sizeof(floor_verts));
// unlocks vertex data
g_floor_vb->Unlock();
// get textures
D3DXCreateTextureFromFile(g_d3d_device, "Floor.bmp", &g_floor_texture);
// Creates a texture from a file.
D3DXCreateTextureFromFileEx(g_d3d_device, "Billboard.bmp", D3DX_DEFAULT, D3DX_DEFAULT,
D3DX_DEFAULT, 0, D3DFMT_A1R5G5B5, D3DPOOL_MANAGED, D3DX_FILTER_TRIANGLE, D3DX_FILTER_TRIANGLE,
D3DCOLOR_RGBA(0,0,0,255), NULL, NULL, &g_billboard_texture);
return TRUE;
}
//--------------------------------------------------------------------------------
// Initialize d3d, d3d device, vertex buffer, texutre; set render state for d3d;
// set perspective matrix.
//--------------------------------------------------------------------------------
BOOL Do_Init()
{
D3DPRESENT_PARAMETERS present_param;
D3DDISPLAYMODE display_mode;
D3DXMATRIX mat_proj, mat_view;
// do a windowed mode initialization of Direct3D
if((g_d3d = Direct3DCreate9(D3D_SDK_VERSION)) == NULL)
return FALSE;
// retrieves the current display mode of the adapter
if(FAILED(g_d3d->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &display_mode)))
return FALSE;
ZeroMemory(&present_param, sizeof(present_param));
// initialize d3d presentation parameter
present_param.Windowed = TRUE;
present_param.SwapEffect = D3DSWAPEFFECT_DISCARD;
present_param.BackBufferFormat = display_mode.Format;
present_param.EnableAutoDepthStencil = TRUE;
present_param.AutoDepthStencilFormat = D3DFMT_D16;
// creates a device to represent the display adapter
if(FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, g_hwnd,
D3DCREATE_SOFTWARE_VERTEXPROCESSING, &present_param, &g_d3d_device)))
return FALSE;
// set render state
// disable d3d lighting
g_d3d_device->SetRenderState(D3DRS_LIGHTING, FALSE);
// enable z-buffer
g_d3d_device->SetRenderState(D3DRS_ZENABLE, D3DZB_TRUE);
// set alpha reference value and function
g_d3d_device->SetRenderState(D3DRS_ALPHAREF, 0x01);
g_d3d_device->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_GREATEREQUAL);
// create and set the projection matrix
// builds a left-handed perspective projection matrix based on a field of view
D3DXMatrixPerspectiveFovLH(&mat_proj, D3DX_PI/4.0, 1.0, 1.0, 1000.0);
// sets a single device transformation-related state
g_d3d_device->SetTransform(D3DTS_PROJECTION, &mat_proj);
// create the meshes
Setup_Mesh();
return TRUE;
}
//--------------------------------------------------------------------------------
// Release all d3d resource.
//--------------------------------------------------------------------------------
BOOL Do_Shutdown()
{
Safe_Release(g_billboard_vb);
Safe_Release(g_billboard_texture);
Safe_Release(g_floor_vb);
Safe_Release(g_floor_texture);
Safe_Release(g_d3d_device);
Safe_Release(g_d3d);
return TRUE;
}
//--------------------------------------------------------------------------------
// Render a frame.
//--------------------------------------------------------------------------------
BOOL Do_Frame()
{
D3DXMATRIX mat_view, mat_world;
// clear device back buffer
g_d3d_device->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_RGBA(0, 64, 128, 255), 1.0f, 0);
// update the view position
float angle = (float) timeGetTime() / 2000.0;
// build view matrix
D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
&D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));
// set view matrix
g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);
// Begin scene
if(SUCCEEDED(g_d3d_device->BeginScene()))
{
// 1) draw the floor
// binds a vertex buffer to a device data stream
g_d3d_device->SetStreamSource(0, g_floor_vb, 0, sizeof(VERTEX));
// set the current vertex stream declation
g_d3d_device->SetFVF(VERTEX_FVF);
// assigns a texture to a stage for a device
g_d3d_device->SetTexture(0, g_floor_texture);
// build world matrix, we only need identity matrix, because we do not need to change original floor position.
D3DXMatrixIdentity(&mat_world);
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// renders a sequence of noindexed, geometric primitives of the specified type from the current set
// of data input stream.
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
// 2) draw the billboards
g_d3d_device->SetStreamSource(0, g_billboard_vb, 0, sizeof(VERTEX));
g_d3d_device->SetTexture(0, g_billboard_texture);
// enable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
// get world matrix, just get it from view matrix's transpose.
D3DXMatrixTranspose(&mat_world, &mat_view);
// draw all billboard images
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
// disable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
// release texture
g_d3d_device->SetTexture(0, NULL);
// end the scene
g_d3d_device->EndScene();
}
// present the contents of the next buffer in the sequence of back buffers owned by the device
g_d3d_device->Present(NULL, NULL, NULL, NULL);
return TRUE;
}
//--------------------------------------------------------------------------------
// Main function, routine entry.
//--------------------------------------------------------------------------------
int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line, int cmd_show)
{
WNDCLASSEX win_class;
MSG msg;
g_inst = inst;
// create window class and register it
win_class.cbSize = sizeof(win_class);
win_class.style = CS_CLASSDC;
win_class.lpfnWndProc = Window_Proc;
win_class.cbClsExtra = 0;
win_class.cbWndExtra = 0;
win_class.hInstance = inst;
win_class.hIcon = LoadIcon(NULL, IDI_APPLICATION);
win_class.hCursor = LoadCursor(NULL, IDC_ARROW);
win_class.hbrBackground = NULL;
win_class.lpszMenuName = NULL;
win_class.lpszClassName = g_class_name;
win_class.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
if(! RegisterClassEx(&win_class))
return FALSE;
// create the main window
g_hwnd = CreateWindow(g_class_name, g_caption, WS_CAPTION | WS_SYSMENU, 0, 0,
WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, inst, NULL);
if(g_hwnd == NULL)
return FALSE;
ShowWindow(g_hwnd, SW_NORMAL);
UpdateWindow(g_hwnd);
// initialize game
if(Do_Init() == FALSE)
return FALSE;
// start message pump, waiting for signal to quit.
ZeroMemory(&msg, sizeof(MSG));
while(msg.message != WM_QUIT)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// draw a frame
if(Do_Frame() == FALSE)
break;
}
// run shutdown function
Do_Shutdown();
UnregisterClass(g_class_name, inst);
return (int) msg.wParam;
}
PURPOSE:
Billboard Demo
Required libraries:
WINMM.lib, D3D9.LIB, D3DX9.LIB.
***************************************************************************************/
#include <windows.h>
#include <stdio.h>
#include "d3d9.h"
#include "d3dx9.h"
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "d3d9.lib")
#pragma comment(lib, "d3dx9.lib")
#pragma warning(disable : 4305 4244)
#define WINDOW_WIDTH 400
#define WINDOW_HEIGHT 400
#define Safe_Release(p) if((p)) (p)->Release();
// window handles, class and caption text.
HWND g_hwnd;
HINSTANCE g_inst;
static char g_class_name[] = "BillboardClass";
static char g_caption[] = "Billboard Demo";
// the Direct3D and device object
IDirect3D9* g_d3d = NULL;
IDirect3DDevice9* g_d3d_device = NULL;
// The 3D vertex format and descriptor
typedef struct
{
float x, y, z; // 3D coordinates
float u, v; // texture coordinates
} VERTEX;
#define VERTEX_FVF (D3DFVF_XYZ | D3DFVF_TEX1)
// the billboard vertex buffer and texture
IDirect3DVertexBuffer9* g_billboard_vb = NULL;
IDirect3DTexture9* g_billboard_texture = NULL;
// the floor vertex buffer and texture
IDirect3DVertexBuffer9* g_floor_vb = NULL;
IDirect3DTexture9* g_floor_texture = NULL;
//--------------------------------------------------------------------------------
// Window procedure.
//--------------------------------------------------------------------------------
long WINAPI Window_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return (long) DefWindowProc(hwnd, msg, wParam, lParam);
}
//--------------------------------------------------------------------------------
// Copy vertex data into vertex buffer, create texture from file.
//--------------------------------------------------------------------------------
BOOL Setup_Mesh()
{
BYTE* vertex_ptr;
VERTEX billboard_verts[] = {
{ -42.0f, 80.0f, 0.0f, 0.0f, 0.0f },
{ 40.0f, 80.0f, 0.0f, 1.0f, 0.0f },
{ -40.0f, 0.0f, 0.0f, 0.0f, 1.0f },
{ 40.0f, 0.0f, 0.0f, 1.0f, 1.0f }
};
VERTEX floor_verts[] = {
{ -100.0f, 0.0f, 100.0f, 0.0f, 0.0f },
{ 100.0f, 0.0f, 100.0f, 1.0f, 0.0f },
{ -100.0f, 0.0f, -100.0f, 0.0f, 1.0f },
{ 100.0f, 0.0f, -100.0f, 1.0f, 1.0f }
};
// create vertex buffers and stuff in data
// for billboard
if(FAILED(g_d3d_device->CreateVertexBuffer(sizeof(billboard_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT,
&g_billboard_vb, NULL)))
return FALSE;
// locks a range of vertex data and obtains a pointer to the vertex buffer memory
if(FAILED(g_billboard_vb->Lock(0, 0, (void**)&vertex_ptr, 0)))
return FALSE;
memcpy(vertex_ptr, billboard_verts, sizeof(billboard_verts));
// unlocks vertex data
g_billboard_vb->Unlock();
// for floor
if(FAILED(g_d3d_device->CreateVertexBuffer(sizeof(floor_verts), 0, VERTEX_FVF, D3DPOOL_DEFAULT, &g_floor_vb, NULL)))
return FALSE;
// locks a range of vertex data and obtains a pointer to the vertex buffer memory
if(FAILED(g_floor_vb->Lock(0, 0, (void**)&vertex_ptr, 0)))
return FALSE;
memcpy(vertex_ptr, floor_verts, sizeof(floor_verts));
// unlocks vertex data
g_floor_vb->Unlock();
// get textures
D3DXCreateTextureFromFile(g_d3d_device, "Floor.bmp", &g_floor_texture);
// Creates a texture from a file.
D3DXCreateTextureFromFileEx(g_d3d_device, "Billboard.bmp", D3DX_DEFAULT, D3DX_DEFAULT,
D3DX_DEFAULT, 0, D3DFMT_A1R5G5B5, D3DPOOL_MANAGED, D3DX_FILTER_TRIANGLE, D3DX_FILTER_TRIANGLE,
D3DCOLOR_RGBA(0,0,0,255), NULL, NULL, &g_billboard_texture);
return TRUE;
}
//--------------------------------------------------------------------------------
// Initialize d3d, d3d device, vertex buffer, texutre; set render state for d3d;
// set perspective matrix.
//--------------------------------------------------------------------------------
BOOL Do_Init()
{
D3DPRESENT_PARAMETERS present_param;
D3DDISPLAYMODE display_mode;
D3DXMATRIX mat_proj, mat_view;
// do a windowed mode initialization of Direct3D
if((g_d3d = Direct3DCreate9(D3D_SDK_VERSION)) == NULL)
return FALSE;
// retrieves the current display mode of the adapter
if(FAILED(g_d3d->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &display_mode)))
return FALSE;
ZeroMemory(&present_param, sizeof(present_param));
// initialize d3d presentation parameter
present_param.Windowed = TRUE;
present_param.SwapEffect = D3DSWAPEFFECT_DISCARD;
present_param.BackBufferFormat = display_mode.Format;
present_param.EnableAutoDepthStencil = TRUE;
present_param.AutoDepthStencilFormat = D3DFMT_D16;
// creates a device to represent the display adapter
if(FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, g_hwnd,
D3DCREATE_SOFTWARE_VERTEXPROCESSING, &present_param, &g_d3d_device)))
return FALSE;
// set render state
// disable d3d lighting
g_d3d_device->SetRenderState(D3DRS_LIGHTING, FALSE);
// enable z-buffer
g_d3d_device->SetRenderState(D3DRS_ZENABLE, D3DZB_TRUE);
// set alpha reference value and function
g_d3d_device->SetRenderState(D3DRS_ALPHAREF, 0x01);
g_d3d_device->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_GREATEREQUAL);
// create and set the projection matrix
// builds a left-handed perspective projection matrix based on a field of view
D3DXMatrixPerspectiveFovLH(&mat_proj, D3DX_PI/4.0, 1.0, 1.0, 1000.0);
// sets a single device transformation-related state
g_d3d_device->SetTransform(D3DTS_PROJECTION, &mat_proj);
// create the meshes
Setup_Mesh();
return TRUE;
}
//--------------------------------------------------------------------------------
// Release all d3d resource.
//--------------------------------------------------------------------------------
BOOL Do_Shutdown()
{
Safe_Release(g_billboard_vb);
Safe_Release(g_billboard_texture);
Safe_Release(g_floor_vb);
Safe_Release(g_floor_texture);
Safe_Release(g_d3d_device);
Safe_Release(g_d3d);
return TRUE;
}
//--------------------------------------------------------------------------------
// Render a frame.
//--------------------------------------------------------------------------------
BOOL Do_Frame()
{
D3DXMATRIX mat_view, mat_world;
// clear device back buffer
g_d3d_device->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_RGBA(0, 64, 128, 255), 1.0f, 0);
// update the view position
float angle = (float) timeGetTime() / 2000.0;
// build view matrix
D3DXMatrixLookAtLH(&mat_view, &D3DXVECTOR3(cos(angle) * 200.0, 200.0, sin(angle) * 200.0),
&D3DXVECTOR3(0.0, 0.0, 0.0), &D3DXVECTOR3(0.0, 1.0, 0.0));
// set view matrix
g_d3d_device->SetTransform(D3DTS_VIEW, &mat_view);
// Begin scene
if(SUCCEEDED(g_d3d_device->BeginScene()))
{
// 1) draw the floor
// binds a vertex buffer to a device data stream
g_d3d_device->SetStreamSource(0, g_floor_vb, 0, sizeof(VERTEX));
// set the current vertex stream declation
g_d3d_device->SetFVF(VERTEX_FVF);
// assigns a texture to a stage for a device
g_d3d_device->SetTexture(0, g_floor_texture);
// build world matrix, we only need identity matrix, because we do not need to change original floor position.
D3DXMatrixIdentity(&mat_world);
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// renders a sequence of noindexed, geometric primitives of the specified type from the current set
// of data input stream.
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
// 2) draw the billboards
g_d3d_device->SetStreamSource(0, g_billboard_vb, 0, sizeof(VERTEX));
g_d3d_device->SetTexture(0, g_billboard_texture);
// enable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
// get world matrix, just get it from view matrix's transpose.
D3DXMatrixTranspose(&mat_world, &mat_view);
// draw all billboard images
for(short i = 0; i < 3; i++)
{
for(short j = 0; j < 3; j++)
{
mat_world._41 = i * 80.0 - 80.0;
mat_world._42 = 0.0;
mat_world._43 = j * 80.0 - 80.0;
// set world matrix
g_d3d_device->SetTransform(D3DTS_WORLD, &mat_world);
// draw polygon
g_d3d_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
}
}
// disable alpha test
g_d3d_device->SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
// release texture
g_d3d_device->SetTexture(0, NULL);
// end the scene
g_d3d_device->EndScene();
}
// present the contents of the next buffer in the sequence of back buffers owned by the device
g_d3d_device->Present(NULL, NULL, NULL, NULL);
return TRUE;
}
//--------------------------------------------------------------------------------
// Main function, routine entry.
//--------------------------------------------------------------------------------
int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line, int cmd_show)
{
WNDCLASSEX win_class;
MSG msg;
g_inst = inst;
// create window class and register it
win_class.cbSize = sizeof(win_class);
win_class.style = CS_CLASSDC;
win_class.lpfnWndProc = Window_Proc;
win_class.cbClsExtra = 0;
win_class.cbWndExtra = 0;
win_class.hInstance = inst;
win_class.hIcon = LoadIcon(NULL, IDI_APPLICATION);
win_class.hCursor = LoadCursor(NULL, IDC_ARROW);
win_class.hbrBackground = NULL;
win_class.lpszMenuName = NULL;
win_class.lpszClassName = g_class_name;
win_class.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
if(! RegisterClassEx(&win_class))
return FALSE;
// create the main window
g_hwnd = CreateWindow(g_class_name, g_caption, WS_CAPTION | WS_SYSMENU, 0, 0,
WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, inst, NULL);
if(g_hwnd == NULL)
return FALSE;
ShowWindow(g_hwnd, SW_NORMAL);
UpdateWindow(g_hwnd);
// initialize game
if(Do_Init() == FALSE)
return FALSE;
// start message pump, waiting for signal to quit.
ZeroMemory(&msg, sizeof(MSG));
while(msg.message != WM_QUIT)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// draw a frame
if(Do_Frame() == FALSE)
break;
}
// run shutdown function
Do_Shutdown();
UnregisterClass(g_class_name, inst);
return (int) msg.wParam;
}
效果图：
