第六章-星空的模擬

OpenGL高級編程

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可視化系統(tǒng)開發(fā)廣東工業(yè)大學(xué)圖學(xué)與數(shù)字媒體系羅立宏第六章星空的模擬6.2編程實例二

6.2.1程序說明模擬太陽系中各大星體的運動，對太陽系進行可視化6.2.2使用到的技術(shù)繪圖坐標(biāo)的變換

注意glPushMatrix,glPopMatrix,glTranslate,glRotate的使用紋理的應(yīng)用

二次曲面紋理的應(yīng)用

raw格式紋理的使用

6.2.3程序閱讀本程序使用了第二章做的OpenGL單文檔模板，在此基礎(chǔ)上開發(fā)而成3.2.2.1繪圖部分代碼繪圖的程序繪圖的工作都是在視圖類的OnDraw()函數(shù)中開始的。因此，可以從OnDraw開始入手，找出繪圖相關(guān)的函數(shù)：◆CMySolarsysView::RenderScene()◆

CMySolarsysView::DrawSun()◆

CMySolarsysView::DrawAllOrbits()◆

CMySolarsysView::DrawPlanets()◆

CMySolarsysView::DrawComet()(1)CMyTerrain1View::RenderScene()//////////////////////////////////////////////////////////// 場景繪制與渲染//////////////////////////////////////////////////////////BOOLCMySolarsysView::RenderScene(){ glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glTranslatef(globalPosition.fPosX,0.0,0.0); glTranslatef(0.0,globalPosition.fPosY,0.0); LightPosition[0]=LightPosition[0]+globalPosition.fPosX;//第一個光源LightPosition[1]=LightPosition[1]+globalPosition.fPosX; LightPosition2[0]=LightPosition2[0]+globalPosition.fPosX;//第二個光LightPosition2[1]=LightPosition2[1]+globalPosition.fPosX; glLightfv(GL_LIGHT1,GL_POSITION,LightPosition); glLightfv(GL_LIGHT2,GL_POSITION,LightPosition2);

globalPosition.fPosX =0; globalPosition.fPosY =0; DrawSun(); //繪制太陽

DrawAllOrbits();

//繪制所有軌道

DrawPlanets();

//繪制所有行星

DrawComet();//繪制彗星 ::SwapBuffers(m_pDC->GetSafeHdc()); //交互緩沖區(qū)

returnTRUE;}(2)CMySolarsysView::DrawSun()//繪制太陽voidCMySolarsysView::DrawSun(){ glPushMatrix(); glutSolidSphere(0.05,10,10); glPopMatrix();}(3)CMySolarsysView::DrawAllOrbits()//繪制行星軌道voidCMySolarsysView::DrawAllOrbits(){ DrawOrbit(mercury); DrawOrbit(venus); DrawOrbit(earth); DrawOrbit(mars); DrawOrbit(jupiter); DrawOrbit(saturn); DrawOrbit(uranus); DrawOrbit(neptune); DrawOrbit(pluto);}(4)voidCMySolarsysView::DrawOrbit()//繪制行星軌道voidCMySolarsysView::DrawOrbit(Planetplanet){ glDisable(GL_LIGHTING); glColor3f(0.7,0.7,0.7);

glBegin(GL_LINE_LOOP); for(inti=0;i<360;i++) { glVertex3f(cos(DEG2RAD(i))*planet.posZ,0,sin(DEG2RAD(i))*planet.posZ); } glEnd(); glEnable(GL_LIGHTING);}(5)CMySolarsysView::DrawPlanets()//繪制9大行星voidCMySolarsysView::DrawPlanets(){ glEnable(GL_TEXTURE_2D);

DrawPlanet(mercury); DrawPlanet(venus); DrawPlanet(earth); DrawPlanet(mars); DrawPlanet(jupiter); DrawPlanet(saturn); DrawPlanet(uranus); DrawPlanet(neptune); DrawPlanet(pluto); glDisable(GL_TEXTURE_2D);}(6)CMySolarsysView::DrawPlanet()//繪制一個行星voidCMySolarsysView::DrawPlanet(Planetplanet){ glPushMatrix(); glRotatef(planet.SolarAngle,0,-1,0); glTranslatef(planet.posX,planet.posY,planet.posZ); glRotatef(planet.OwnAxisAngle,0,-1,0); glRotatef(90.0,1.0,0.0,0.0);

glBindTexture(GL_TEXTURE_2D,texture_id[planet.TextureID]); GLUquadricObj*q=gluNewQuadric();//新建一個二次曲面對象

gluQuadricDrawStyle(q,GLU_FILL);

//繪圖風(fēng)格

gluQuadricNormals(q,GLU_SMOOTH);//指定法線方式gluQuadricTexture(q,GL_TRUE);

//設(shè)置使用紋理

gluSphere(q,planet.size,planet.sections,planet.sections);//繪制球體

gluDeleteQuadric(q);

//刪除二次曲面對象

glPopMatrix();}繪圖坐標(biāo)系變換過程：開始繪圖坐標(biāo)系在世界坐標(biāo)系的原點，圖中紅色為x，綠色為y，藍色為z0//公轉(zhuǎn)。繞y軸(綠色)旋轉(zhuǎn)，如45°

glRotatef(planet.SolarAngle,0,-1,0);12//沿z軸(藍色)移動，如(0,0,5)glTranslatef(planet.posX,planet.posY,planet.posZ);3//自轉(zhuǎn)。繞y軸(綠色)旋轉(zhuǎn)，如30°

glRotatef(planet.SolarAngle,0,-1,0);4//把z軸轉(zhuǎn)為向上，使行星北極朝上。繞x軸轉(zhuǎn)90°glRotatef(90.0,1.0,0.0,0.0);5//在當(dāng)前繪圖坐標(biāo)系繪制球體（行星）gluSphere(q,planet.size,planet.sections,planet.sections);(7)CMySolarsysView::DrawComet()//繪制彗星voidCMySolarsysView::DrawComet(){ glPushMatrix(); glRotatef(iCometAngle,0,0,1); glTranslatef(1,0,0); glutSolidSphere(0.02,20,20); glPopMatrix();}3.2.2.2動畫的實現(xiàn)動畫的實現(xiàn)一般靠OnTimer()改變繪圖參數(shù)，然后刷新屏幕。重新畫圖時由于數(shù)據(jù)不一樣，就畫出了與剛才不一樣的圖，就產(chǎn)生了動畫。OnTimer()中發(fā)現(xiàn)改變參數(shù)的函數(shù)是：◆CMySolarsysView::rotate()(1)CMySolarsysView::rotate()voidCMySolarsysView::rotate(){ if(globalPosition.bRotationOn) { //comet iCometAngle+=2; if(iCometAngle>=360) {

iCometAngle-=360; } //solarrotation mercury.SolarAngle+=1.6*ROTATION_SPEED; if(mercury.SolarAngle>=360){mercury.SolarAngle-=360;}

……

//金星至海王星省略

……

pluto.SolarAngle+=0.01*ROTATION_SPEED; if(pluto.SolarAngle>=360) {pluto.SolarAngle-=360;} //axisrotation mercury.OwnAxisAngle+=0.1; if(mercury.OwnAxisAngle>=360) {mercury.OwnAxisAngle-=360;}

……

//金星至海王星省略 ……

pluto.OwnAxisAngle+=3; if(pluto.OwnAxisAngle>=360) {pluto.OwnAxisAngle-=360;} }}3.2.2.3初始化代碼查看一下程序常用于初始化的地方（如App類的InitInstance()、視圖類的OnCreate()等）有沒有額外的初始化代碼，發(fā)現(xiàn)有：◆CMySolarsysView::Init()◆CMySolarsysView::InitPlanets()

這些函數(shù)應(yīng)包括了各星體數(shù)據(jù)的初始化(1)CMySolarsysView::Init()voidCMySolarsysView::Init(void){ glLightfv(GL_LIGHT1,GL_AMBIENT,LightAmbient); glLightfv(GL_LIGHT1,GL_DIFFUSE,LightDiffuse); glLightfv(GL_LIGHT1,GL_POSITION,LightPosition); glEnable(GL_LIGHT1);//啟用1號光源

glLightfv(GL_LIGHT2,GL_AMBIENT,LightAmbient2); glLightfv(GL_LIGHT2,GL_DIFFUSE,LightDiffuse2); glLightfv(GL_LIGHT2,GL_POSITION,LightPosition2); glEnable(GL_LIGHT2);//啟用2號光源

glClearColor(0,0,0,0);//設(shè)置清屏顏色

glShadeModel(GL_SMOOTH);//設(shè)置面著色模式為平滑模式

glEnable(GL_DEPTH_TEST);//啟用深度測試

glEnable(GL_LIGHTING);

//啟用光照功能

glEnable(GL_CULL_FACE);//啟用無用面剔除功能

m_Textures.LoadTextures(texture_id,MAX_NO_TEXTURES); globalPosition.fPosX=0; globalPosition.fPosY=0; globalPosition.iDegreesX=20;

globalPosition.iDegreesY=25; globalPosition.bRotationOn=true;//等于true才不斷旋轉(zhuǎn) //旋轉(zhuǎn)繪圖坐標(biāo)系，讓用戶看到太陽系的全貌。配合OnSize()中//的glTranslatef(0.0,0.0,-5.0)就能得到觀察的效果

glRotatef(globalPosition.iDegreesX,0.0,1.0,0.0); glRotatef(globalPosition.iDegreesY,1.0,0.0,0.0);}觀察位置的設(shè)置0圖中為繪圖坐標(biāo)系1//繪圖坐標(biāo)系繞y軸旋轉(zhuǎn)20°glRotatef(globalPosition.iDegreesX,0.0,1.0,0.0);2//繪圖坐標(biāo)系繞x軸旋轉(zhuǎn)25°glRotatef(globalPosition.iDegreesY,1.0,0.0,0.0);3//在OnDraw()中畫了整個太陽系4//把原始的觀察坐標(biāo)系畫出來，它是左手系5//在OnSize中有以下代碼，把觀察坐標(biāo)系向z負向移動了5glMatrixMode(GL_PROJECTION);glTranslatef(0.0,0.0,-5.0);6//把視點移至觀察坐標(biāo)系來看，發(fā)現(xiàn)看的東西是這樣的：(2)CTextures::LoadTextures()//加載9個行星的紋理voidCTextures::LoadTextures(GLuint*texture_id,intMaxNrOfTextures){ glPixelStorei(GL_UNPACK_ALIGNMENT,1);//對齊像素字節(jié)glGenTextures(MaxNrOfTextures,texture_id);//生成9個紋理對象

//加載水星紋理

glBindTexture(GL_TEXTURE_2D,texture_id[0]);//紋理準(zhǔn)備加載到0號

//以下load_texture()函數(shù)封裝了加載raw圖像的方法，以后需要使用raw//格式圖像時大家可直接使用

if(load_texture("mercury.raw",640,320,3,GL_RGB,GL_NEAREST)) { MessageBox(NULL,TEXTURE_LOAD_ERROR,"Error",MB_OK); exit(1); }

…………

glBindTexture(GL_TEXTURE_2D,texture_id[8]); if(load_texture("pluto.raw",640,320,3,GL_RGB,GL_NEAREST)) { MessageBox(NULL,TEXTURE_LOAD_ERROR,"Error",MB_OK); exit(1); }}(3)