实验三、画圆与凸多边形填充算法.doc

华北水利水电大学 计算机图形学 实验报告2017-2018学年 第一学期 2014级 计算机科学与技术 专业 指导老师 曹源昊 班级 2014157 学号 201415717 姓名 李卫朋 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)以及线宽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，建议坐标轴的范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800，y方向高为6003. 算法描述使用OpenGL进行画图，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。/#include stdio.h#include stdafx.h#include glut.h#include stdlib.h#include math.h#include iostreamusing namespace std;GLsizei winWidth = 400, winHeight = 300; / 屏幕显示宽高.int a100,b100,c100,d100,n=-1;void init( )glClearColor(1.0, 1.0, 1.0, 1.0);glMatrixMode(GL_PROJECTION);gluOrtho2D(0.0, 200.0, 0.0, 150.0);void lineBres(int x0,int y0,int xEnd,int yEnd) 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; 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 displayFcn() glColor3f(1.0, 0.0, 0.0); for(int i=0;i=n;i+) lineBres(ai,bi,ci,di);glFlush();void winReshpeFcn(GLint newWidth, GLint newHeight)glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, GLdouble(newWidth), 0.0, GLdouble(newHeight);glClear(GL_COLOR_BUFFER_BIT);winWidth = newWidth;winHeight = newHeight;int _tmain(int argc, char* argv)glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition(100, 100);glutInitWindowSize(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(displayFcn);printf(继续输入请按1，退出请按0);scanf_s(%d,&h);glutReshapeFunc(winReshpeFcn);glutMainLoop();return 0;（2）/ 中点画圆法.cpp : 定义控制台应用程序的入口点。/#include stdafx.h#include glut.h#include stdlib.h#include math.h#include iostreamusing namespace std;const GLdouble twoPi = 6.283185;GLsizei winWidth = 400, winHeight = 300; / 屏幕显示宽高.class screenPt public:screenPt()x = y = 0;GLint x, y;void setCoords(GLint xCoordValue, GLint yCorrdValue)x = xCoordValue;y = yCorrdValue;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(GLint xCoord, GLint yCoord)glBegin(GL_POINTS);glVertex2i(xCoord, yCoord);glEnd();void circleMidpoint(GLint xc, GLint yc, GLint radius)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.incrementy();p += 2 * (circPt.getx() - circPt.gety() + 1;circlePlotPoints(xc, yc, circPt);void circlePlotPoints(GLint xc, GLint yc, screenPt circPt)setPixel(xc + circPt.getx(), yc + circPt.gety();setPixel(xc - circPt.getx(), yc + circPt.gety();setPixel(xc + circPt.getx(), yc - circPt.gety();setPixel(xc - 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; circCtr.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(circCtr.x+30, circCtr.y-30, radius);glColor3f(0.0, 1.0, 0.0); circleMidpoint(circCtr.x+90, circCtr.y-30, radius);void displayFcn( )glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0, 0.0, 0.0); pieChart();glFlush();void winReshpeFcn(GLint newWidth, GLint newHeight)glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, GLdouble(newWidth), 0.0, GLdouble(newHeight);glClear(GL_COLOR_BUFFER_BIT);winWidth = newWidth;winHeight = newHeight;int _tmain(int argc, char* argv)glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition(100, 100);glutInitWindowSize(winWidth, winHeight);glutCreateWindow(Pie Chart);init();glutDisplayFunc(displayFcn);glutReshapeFunc(winReshpeFcn);glutMainLoop();（3）#include stdafx.hconst int POINTNUM=10; /多边形点数./*定义结构体用于活性边表AET和新边表NET*/typedef struct XETfloat x;float dx,ymax;XET* next;AET,NET;/*定义点结构体point*/struct pointfloat x;float y;polypointPOINTNUM=100, 200, 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(扫描到此结束)int MaxY=0;int i;for(i=0;iMaxY)MaxY=polypointi.y;/初始化AET表AET *pAET=new AET;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(0.0,0.0,0.0); /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=new NET;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;if(polypoint(j+1+POINTNUM)%POINTNUM.ypolypointj.y)NET *p=new NET; 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=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;/(改进算法)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-next;/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)