第11讲 天空文档格式.docx
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#defineD3DFVF_CUSTOMVETEX2（D3DFVF_XYZ|D3DFVF_TEX1）
classCCubeSky
private:
LPDIRECT3DDEVICE9m_pd3dDevice;
LPDIRECT3DVERTEXBUFFER9m_pVB;
LPDIRECT3DINDEXBUFFER9m_pIB;
LPDIRECT3DTEXTURE9m_pTexScene[6];
floatlen;
public:
CCubeSky（LPDIRECT3DDEVICE9pd3dDevice）;
~CCubeSky（void）;
HRESULTVBInit（）;
voidRender（）;
boolSetTexture（constWCHAR*FileTexture,intflag）;
CCubeSky.cpp
#include"
CubeSky.h"
CCubeSky:
:
CCubeSky（LPDIRECT3DDEVICE9pd3dDevice）
m_pd3dDevice=pd3dDevice;
this->
m_pIB=NULL;
m_pVB=NULL;
len=100.0f;
}
~CCubeSky（void）
{}
HRESULTCCubeSky:
VBInit（）
//创建天空盒需要的8个顶点
CUSTOMVERTEX2gCubeVerts[]=
{
//z方向点和纹理坐标
{-len,0.0f,-len,1.0f,1.0f},//0
{-len,len,-len,1.0f,0.0f},//1
{len,0.0f,-len,0.0f,1.0f},//2
{len,len,-len,0.0f,0.0f},//3
{len,0.0f,len,1.0f,1.0f},//4
{len,len,len,1.0f,0.0f},//5
{-len,0.0f,len,0.0f,1.0f},//6
{-len,len,len,0.0f,0.0f},//7
//x方向点和纹理坐标
{len,0.0f,-len,1.0f,1.0f},//2-8
{len,len,-len,1.0f,0.0f},//3-9
{len,0.0f,len,0.0f,1.0f},//4-10
{len,len,len,0.0f,0.0f},//5-11
{-len,0.0f,-len,0.0f,1.0f},//0-12
{-len,len,-len,0.0f,0.0f},//1-13
{-len,0.0f,len,1.0f,1.0f},//6-14
{-len,len,len,1.0f,0.0f},//7-15
//y方向点和纹理坐标
{-len,0.0f,-len,1.0f,0.0f},//0-16
{len,0.0f,-len,0.0f,0.0f},//2-17
{-len,0.0f,len,1.0f,1.0f},//6-18
{len,0.0f,len,0.0f,1.0f},//4-19
{-len,len,-len,1.0f,1.0f},//1-20
{len,len,-len,0.0f,1.0f},//3-21
{len,len,len,0.0f,0.0f},//5-22
{-len,len,len,1.0f,0.0f},//7-23
};
//创建天空盒需要的顶点的索引
WORDgCubeIndices[]=
{2,3,1,//z方向
2,1,0,//
6,7,5,//
6,5,4,//
10,11,9,//x方向
10,9,8,//
12,13,15,//
12,15,14,//
16,18,19,//y方向
16,19,17,//
20,21,22,//
20,22,23
//创建顶点缓冲区
if（FAILED（m_pd3dDevice->
CreateVertexBuffer（sizeof（gCubeVerts）,
0,
D3DFVF_CUSTOMVETEX2,
D3DPOOL_DEFAULT,
&
m_pVB,
NULL
）））
returnE_FAIL;
}
VOID*pVertices;
//锁定顶点缓冲区
if（FAILED（m_pVB->
Lock（0,sizeof（gCubeVerts）,
（void**）&
pVertices,0）））
//把顶点数组的数据拷贝到顶点缓冲区中
memcpy（pVertices,gCubeVerts,sizeof（gCubeVerts））;
m_pVB->
Unlock（）;
//解锁顶点缓冲区
//创建索引缓冲区
CreateIndexBuffer（sizeof（gCubeIndices）,
D3DFMT_INDEX16,
m_pIB,
VOID*pIndices;
//锁定索引缓冲区
if（FAILED（m_pIB->
Lock（0,sizeof（gCubeIndices）,
pIndices,0）））
//把索引数组的值拷贝索引缓冲区中
memcpy（pIndices,gCubeIndices,sizeof（gCubeIndices））;
m_pIB->
//解锁索引缓冲区
returnS_OK;
boolCCubeSky:
SetTexture（constWCHAR*FileTexture,intflag）
if（FAILED（D3DXCreateTextureFromFile（m_pd3dDevice,FileTexture,
m_pTexScene[flag]）））
returnfalse;
returntrue;
voidCCubeSky:
Render（）
D3DXMATRIXmatrix,smatrix,tmatrix,rmatrix;
//m_Camera.ProcInput（）;
//设置数据源
m_pd3dDevice->
SetStreamSource（0,m_pVB,0,sizeof（CUSTOMVERTEX2））;
SetFVF（D3DFVF_CUSTOMVETEX2）;
SetIndices（m_pIB）;
SetRenderState（D3DRS_CULLMODE,D3DCULL_CCW）;
//背面消隐
SetRenderState（D3DRS_LIGHTING,false）;
//光照关闭
SetRenderState（D3DRS_ZENABLE,false）;
//关闭Zbuffer
//SetProjection（）;
//投影
//画天空盒设置纹理
SetTexture（0,m_pTexScene[0]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,0,4,0,2）;
SetTexture（0,m_pTexScene[1]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,4,4,6,2）;
SetTexture（0,m_pTexScene[2]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,8,4,12,2）;
SetTexture（0,m_pTexScene[3]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,12,4,18,2）;
SetTexture（0,m_pTexScene[4]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,16,4,24,2）;
SetTexture（0,m_pTexScene[5]）;
DrawIndexedPrimitive（D3DPT_TRIANGLELIST,0,20,4,30,2）;
球形天空构造
球面天空是通过在半球面上进行纹理贴图实现的，因此，需要分割一个半球面获得各个顶点，然后定义顶点的灵活顶点格式，设置和计算每个顶点的xyz坐标和纹理uv坐标，最后将顶点数据送入渲染管道流水线进行处理，如图所示
假设半球面上的任意点p=（px,py,pz）半球体的半径为r，α和β为相应的经度角和纬度角，如图下所示。
从图中可以看出，经度角α的取值范围在区间[0,2π]内，而纬度角β的取值范围在区间[0,π/2]内。
所以顶点p的坐标计算公式如下：
接下来考虑纹理坐标的计算。
若将2π除以经度角就可以得到维度线的条数，而若将π/2除以维度角就可以得到经度线的条数。
因此，根据p点的经度角α和维度角β就可以计算出p点的纹理坐标。
可以按照下面代码计算出p点的坐标和纹理坐标。
m_fSkyboxRadius=fRadius;
//半球体的半径
m_nNumLatitudes=360/nAlpha;
//维度线的条数
m_nNumLongitudes=90/nBeta;
//经度线的条数
m_nVertsPerLongi=m_nNumLatitudes+1;
//每条经度线上的顶点数
m_nVertsPerLati=m_nNumLongitudes+1;
//每条维度线上的顶点数
m_nNumVertices=m_nVertsPerLati*m_nVertsPerLongi;
//灵活顶点格式
structSkyBoxVERTEX
FLOAT_x,_y,_z;
FLOAT_u,_v;
SkyBoxVERTEX（FLOATx,FLOATy,FLOATz,FLOATu,FLOATv）
:
_x（x）,_y（y）,_z（z）,_u（u）,_v（v）{}
staticconstDWORDFVF=D3DFVF_XYZ|D3DFVF_TEX1;
//计算地形的灵活顶点
if（FAILED（m_pd3dDevice->
CreateVertexBuffer（m_nNumVertices*sizeof（SKYBOXVERTEX）,
D3DUSAGE_WRITEONLY,SKYBOXVERTEX:
FVF,D3DPOOL_MANAGED,&
m_pVertexBuf,0）））
returnFALSE;
SKYBOXVERTEX*pVertices=NULL;
m_pVertexBuf->
Lock（0,0,（void**）&
pVertices,0）;
intnIndex=0;
FLOATfAlpha=2.0f*D3DX_PI*nAlpha/360.0f;
//经度角转换为弧度表示
FLOATfBeta=2.0f*D3DX_PI*nBeta/360.0f;
//维度角转换为弧度表示
for（introw=0;
row<
m_nNumLongitudes+1;
row++）
for（intcol=0;
col<
m_nNumLatitudes+1;
col++）
//计算顶点的坐标
pVertices[nIndex]._x=fRadius*cosf（row*fBeta）*cosf（col*fAlpha）;
pVertices[nIndex]._y=fRadius*sinf（row*fBeta）;
pVertices[nIndex]._z=fRadius*cosf（row*fBeta）*sinf（col*fAlpha）;
//计算顶点的纹理坐标
pVertices[nIndex]._u=col*fAlpha/（2.0f*D3DX_PI）;
pVertices[nIndex]._v=row*fBeta/（D3DX_PI/2.0f）;
nIndex++;
对于半球面上的任意点A，并以该点为起始顶点的两个相邻三角形的顶点B、C、D点，它们的位置关系将如图所示。
pIndices[nIndex+0]=row*m_nVertsPerLongi+col;
pIndices[nIndex+1]=（row+1）*m_nVertsPerLongi+col;
pIndices[nIndex+2]=（row+1）*m_nVertsPerLongi+col+1;
pIndices[nIndex+3]=row*m_nVertsPerLongi+col;
pIndices[nIndex+4]=（row+1）*m_nVertsPerLongi+col+1;
pIndices[nIndex+5]=row*m_nVertsPerLongi+col+1;
nIndex+=6;
球形天空类定义：
CSkyBox.h
classCSkybox
LPDIRECT3DTEXTURE9m_pTexture;
LPDIRECT3DINDEXBUFFER9m_pIndexBuf;
LPDIRECT3DVERTEXBUFFER9m_pVertexBuf;
INTm_nNumLatitudes;
//维度的数目
INTm_nNumLongitudes;
//经度的数目
INTm_nVertsPerLati;
//每条维度上包含的顶点数
INTm_nVertsPerLongi;
//每条经度上包含的顶点数
INTm_nNumVertices;
//顶点总数
FLOATm_fSkyboxRadius;
//球形天空的半径
structSKYBOXVERTEX//球形天空的顶点结构
SKYBOXVERTEX（FLOATx,FLOATy,FLOATz,FLOATu,FLOATv）
CSkybox（IDirect3DDevice9*pd3dDevice）;
virtual~CSkybox（void）;
BOOLLoadSkybox（wchar_t*pTextureFile）;
//加载纹理
BOOLInitSkybox（INTnAlpha,INTnBeta,FLOATnRadius）;
//初始化球形天空
BOOLDrawSkybox（D3DXMATRIX*pMatWorld,BOOLbDrawFrame=FALSE）;
//绘制天空
球形天空类的实现SkyBox.cpp
SkyBox.h"
CSkyBox:
CSkyBox（IDirect3DDevice9*pd3dDevice）
m_pTexture=NULL;
m_pIndexBuf=NULL;
m_pVertexBuf=NULL;
m_nNumVertices=0;
m_nNumLatitudes=0;
m_nNumLongitudes=0;
m_nVertsPerLongi=0;
m_nVertsPerLati=0;
m_fSkyBoxRadius=0;
~CSkyBox（void）
if（m_pIndexBuf!
=NULL）
m_pIndexBuf->
Release（）;
if（m_pTexture!
m_pTexture->
if（m_pVertexBuf!
m_pVertexBuf->
BOOLCSkyBox:
LoadSkyBox（wchar_t*pTextureFile）
//加载天空纹理
if（FAILED（D3DXCreateTextureFromFile（m_pd3dDevice,pTextureFile,&
m_pTexture）））
returnTRUE;
InitSkyBox（INTnAlpha,INTnBeta,FLOATfRadius）
m_fSkyBoxRadius=fRadius;
//半球体的半径
m_nNumLatitudes=360/nAlpha;
//维度线的条数
m_nNumLongitudes=90/nBeta;
//经度线的条数
m_nVertsPerLongi=m_nNumLatitudes+1;
//每条经度线上的顶点数
m_nVertsPerLati=m_nNumLongitudes+1;
m_nNumVertices=m_nVertsPerLati*m_nVertsPerLongi;
//计算天空的灵活顶点
CreateVertexBuffer（m_nNumVertices*sizeof（SkyBoxVERTEX）,
D3DUSAGE_WRITEONLY,SkyBoxVERTEX:
FVF,D3DPOOL_MANAGED,&
m_pVertexBuf,0）））
SkyBoxVERTEX*pVertices=NULL;
m_pVertexBuf->
intnIndex=0;
FLOATfAlpha=2.0f*D3DX_PI*nAlpha/360.0f;
FLOATfBeta=2.0f*D3DX_PI*nBeta/360.0f;
for（introw=0;
Unlock（
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