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1、word华北水利水电大学 计算机图形学 实验报告计算机科学与技术 专业实验三、画圆与凸多边形填充算法1. 实验目的练习直线和圆的光栅扫描线算法，多边形的扫描转换算法。2. 实验内容和要求按要求完成以下三个作业。提交纸质实验报告，同时提交实验报告和源代码的电子版。(I). 利用Bresenham直线扫描算法绘制任意直线段。输入为起点坐标(x0,y0)和终点坐标(x1,y1)以与线宽w,利用Bresenham算法计算离散的近似像素点，并在OpenGL窗口中绘制该线段。要求绘制至少五条线段，具有不同的斜率，不同的起点和终点，不同的线宽。不允许直接调用GL_LINES来实现。(II). 利用中点画圆算
2、法绘制圆。输入为圆心(xc,yc)和圆的的半径r，利用中点画圆算法计算离散的近似像素点，并在OpenGL窗口中绘制。要求绘制至少四个圆，构成一个图案，比如奥迪车标或五环。(III). 实现多边形的扫描转换算法。输入一个凸多边形的顶点序列，利用活性边表计算每条扫描线上位于多边形内部的像素，并填充上一个新颜色,最终达到填充多边形内部的目的。建议：为了实现坐标点和像素的一一对应，建议坐标轴的X围和窗口像素宽高一致，比如：glutInitWindowSize(800, 600);/像素宽800，高600坐标系设定为：gluOrtho2D(-400, 400, -300, 300);/坐标轴x方向宽为8
3、00，y方向高为6003. 算法描述使用OpenGL进展画图，采用VS编程环境。4. 源程序代码1/ bresenham直线.cpp : 定义控制台应用程序的入口点。/#includestdio.h#includestdafx.h#includeglut.h#includestdlib.h#includemath.h#includeiostreamusingnamespace std;GLsizei winWidth = 400, winHeight = 300; / 屏幕显示宽高.int a100,b100,c100,d100,n=-1;void init( )glClearColor(1.
4、0, 1.0, 1.0, 1.0);glMatrixMode(GL_PROJECTION);gluOrtho2D(0.0, 200.0, 0.0, 150.0);void lineBres(intx0,inty0,intxEnd,intyEnd)int dx = abs(xEnd - x0),dy = abs(yEnd - y0);int p = 2*dy - dx;int twoDy = 2*dy, twoDyMinusDx = 2*(dy - dx);int x,y;if(x0 xEnd) x = xEnd; y = yEnd;xEnd = x0;else x = x0; y = y0;
5、glBegin(GL_POINTS); glVertex2i(x,y); glEnd();while(xxEnd) x+;if(p 0)p += twoDy;elsey+;p += twoDyMinusDx;glBegin(GL_POINTS); glVertex2i(x,y); glEnd(); void displayF()glColor3f(1.0, 0.0, 0.0); for(int i=0;i=n;i+) lineBres(ai,bi,ci,di);glFlush();void winReshpeF(GLintnewWidth, GLintnewHeight)glMatrixMod
6、e(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, GLdouble(newWidth), 0.0, GLdouble(newHeight);glClear(GL_COLOR_BUFFER_BIT);winWidth = newWidth;winHeight = newHeight;int_tmain(intargc, char* argv)glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition(100, 100);glutI
7、nitWindowSize(winWidth, winHeight);glutCreateWindow(bresenham直线);init();int h=1;while(h=1)printf(输入起点和终点的坐标);n+;scanf_s(%d %d %d %d,&an,&bn,&cn,&dn);glutDisplayFunc(displayF);printf(继续输入请按1，退出请按0);scanf_s(%d,&h);glutReshapeFunc(winReshpeF);glutMainLoop();return 0;2/ 中点画圆法.cpp : 定义控制台应用程序的入口点。/#inclu
8、destdafx.h#includeglut.h#includestdlib.h#includemath.h#includeiostreamusingnamespace std;constGLdouble twoPi = 6.283185;GLsizei winWidth = 400, winHeight = 300; / 屏幕显示宽高.classscreenPt public:screenPt()x = y = 0;GLint x, y;void setCoords(GLintxCoordValue, GLintyCorrdValue)x = xCoordValue;y = yCorrdVa
9、lue;GLint getx() constreturn x;GLint gety() constreturn y;void incrementx()x+;void incrementy()y-;void init( )glClearColor(1.0, 1.0, 1.0, 1.0);glMatrixMode(GL_PROJECTION);gluOrtho2D(0.0, 200.0, 0.0, 150.0);void setPixel(GLintxCoord, GLintyCoord)glBegin(GL_POINTS);glVertex2i(xCoord, yCoord);glEnd();v
10、oid circleMidpoint(GLintxc, GLintyc, GLintradius)screenPt circPt;GLint p = 1 - radius;/中点参数初值circPt.setCoords(0, radius);void circlePlotPoints(GLint, GLint, screenPt);circlePlotPoints(xc, yc, circPt);while (circPt.getx() circPt.gety()circPt.incrementx();if (p 0)p += 2 * circPt.getx() + 1;elsecircPt.
11、incrementy();p += 2 * (circPt.getx() - circPt.gety() + 1;circlePlotPoints(xc, yc, circPt);void circlePlotPoints(GLintxc, GLintyc, screenPtcircPt)setPixel(xc + circPt.getx(), yc + circPt.gety();setPixel(xc - circPt.getx(), yc + circPt.gety();setPixel(xc + circPt.getx(), yc - circPt.gety();setPixel(xc
12、 - circPt.getx(), yc - circPt.gety();setPixel(xc + circPt.gety(), yc + circPt.getx();setPixel(xc - circPt.gety(), yc + circPt.getx();setPixel(xc + circPt.gety(), yc - circPt.getx();setPixel(xc - circPt.gety(), yc - circPt.getx();void pieChart( )screenPt circCtr, piePt;GLint radius = winWidth / 16; c
13、ircCtr.x = winWidth / 4; circCtr.y = winHeight / 1.5;circleMidpoint(circCtr.x, circCtr.y, radius); / 调用中点画圆方法 glColor3f(0.0, 0.0, 1.0); circleMidpoint(circCtr.x+60, circCtr.y, radius);glColor3f(0.0, 0.0, 0.0); circleMidpoint(circCtr.x+120, circCtr.y, radius); glColor3f(1.0, 1.0, 0.0); circleMidpoint
14、(circCtr.x+30, circCtr.y-30, radius);glColor3f(0.0, 1.0, 0.0); circleMidpoint(circCtr.x+90, circCtr.y-30, radius);void displayF( )glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0, 0.0, 0.0); pieChart();glFlush();void winReshpeF(GLintnewWidth, GLintnewHeight)glMatrixMode(GL_PROJECTION);glLoadIdentity();gl
15、uOrtho2D(0.0, GLdouble(newWidth), 0.0, GLdouble(newHeight);glClear(GL_COLOR_BUFFER_BIT);winWidth = newWidth;winHeight = newHeight;int_tmain(intargc, char* argv)glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition(100, 100);glutInitWindowSize(winWidth, winHeight);g
16、lutCreateWindow(Pie Chart);init();glutDisplayFunc(displayF);glutReshapeFunc(winReshpeF);glutMainLoop();3#includestdafx.hconstint POINTNUM=10; /多边形点数./*定义结构体用于活性边表AET和新边表NET*/typedefstructXETfloat x;float dx,ymax;XET* next;AET,NET;/*定义点结构体point*/structpointfloat x;float y;polypointPOINTNUM=100, 200,
17、122, 131, 195, 131, 136, 88, 159, 19, 100, 62, 41, 19, 64, 88, 5, 131, 78, 131;/五角星void PolyScan()/计算最高点的y坐标(扫描到此完毕)int MaxY=0;int i;for(i=0;iMaxY)MaxY=polypointi.y;/初始化AET表AET *pAET=newAET;pAET-next=NULL;/初始化NET表NET *pNET1024;for(i=0;inext=NULL;glClear(GL_COLOR_BUFFER_BIT); /赋值的窗体显示. glColor3f(0.0,
18、0.0,0.0); /设置直线的颜色红色glBegin(GL_POINTS);/扫描并建立NET表for(i=0;i=MaxY;i+)for(int j=0;jpolypointj.y)NET *p=newNET;p-x=polypointj.x;p-ymax=polypoint(j-1+POINTNUM)%POINTNUM.y;p-dx=(polypoint(j-1+POINTNUM)%POINTNUM.x-polypointj.x)/(polypoint(j-1+POINTNUM)%POINTNUM.y-polypointj.y);p-next=pNETi-next;pNETi-next=
19、p;if(polypoint(j+1+POINTNUM)%POINTNUM.ypolypointj.y)NET *p=newNET; p-x=polypointj.x;p-ymax=polypoint(j+1+POINTNUM)%POINTNUM.y;p-dx=(polypoint(j+1+POINTNUM)%POINTNUM.x-polypointj.x)/(polypoint(j+1+POINTNUM)%POINTNUM.y-polypointj.y);p-next=pNETi-next;pNETi-next=p;/建立并更新活性边表AETfor(i=0;inext;while(p)p-x
20、=p-x + p-dx;p=p-next;/更新后新AET先排序/断表排序,不再开辟空间AET *tq=pAET;p=pAET-next;tq-next=NULL;while(p)while(tq-next & p-x = tq-next-x)tq=tq-next;NET *s=p-next;p-next=tq-next;tq-next=p;p=s;tq=pAET;/(改良算法)先从AET表中删除ymax=i的结点AET *q=pAET;p=q-next;while(p)if(p-ymax=i)q-next=p-next;delete p;p=q-next;elseq=q-next;p=q-n
21、ext;/将NET中的新点增加AET,并用插入法按X值递增排序p=pNETi-next;q=pAET;while(p)while(q-next & p-x = q-next-x)q=q-next;NET *s=p-next;p-next=q-next;q-next=p;p=s;q=pAET;/配对填充颜色p=pAET-next;while(p & p-next)for(float j=p-x;jnext-x;j+)glVertex2i(static_cast(j),i);p=p-next-next;/考虑端点情况glEnd();glFlush(); void init(void)glClear
22、Color(1.0,1.0,1.0,1.0);/窗体的背景颜色设置为白色glMatrixMode(GL_PROJECTION);/gluOrtho2D(0.0,600.0,0.0,450.0);gluOrtho2D(-400, 400, -300, 300);void main(intargc,char* argv) glutInit(&argc,&argv); /I初始化 GLUT. glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); /设置显示模式：单个缓存和使用RGB模型 glutInitWindowPosition(50,100); /设置窗体的顶部和左边位置 glutInitWindowSize(800,600); /设置窗体的高度和宽度 glutCreateWindow(五角星); /创建显示窗体 init(); glutDisplayFunc(PolyScan); glutMainLoop(); 5. 实验结果12319 / 19
