计算机图形学（第三版）中心画圆法算法代码

#include "Dependencies\glew\glew.h" #include "Dependencies\freeglut\freeglut.h" #include <stdio.h> GLint array[1000][2]; //保存要显示的坐标点 int length=0; class screenPt { private: GLint x, y; public: /* Default Constructor:initializes coordinate position to (0,0). */ screenPt() { x = y = 0; } void setCoords(GLint xCoordValue, GLint yCoordValue) { x = xCoordValue; y = yCoordValue; } GLint getx() const { return x; } GLint gety() const { return y; } void incrementx() { x++; } void decrementy() { y--; } }; void init(void) { glClearColor(1.0, 1.0, 1.0, 0.0);//窗口颜色(红:[0.0~1.0]R, 绿:[0.0~1.0]G，蓝:[0.0~1.0]B, 透明度:[0.0~1.0]A) /*使用正投影将世界坐标系二位矩形区域的内容映射到屏幕上，区域的x坐标值从0.0到200.0，y坐标值从0.0到150.0*/ glMatrixMode(GL_PROGRAM); gluOrtho2D(0.0, 200.0, 0.0, 150.0); } void setPixel(void) { glClear(GL_COLOR_BUFFER_BIT);//GL_COLOR_BUFFER_BIT是一个OpenGL符号常量，用来指定它的颜色缓存（刷新缓存）中的位值，该缓存将使用glClearColor函数中指定的值来设定。 glColor3f(1.0f, 0.0f, 0.0f);//设置线段颜色为红色 glPointSize(5.f); //设置点的大小 glBegin(GL_POINTS); for (size_t i = 0; i <=length; i++) { glVertex2i(array[i][1], array[i][2]); } glEnd(); glFlush();//执行所有的OpenGL程序 } 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()); printf("(%d,%d)\n", xc + circPt.getx(), yc + circPt.gety()); //要显示的坐标点保存至array[1000][2] array[length][1] = xc + circPt.getx(), array[length][2] = yc + circPt.gety(); } void circleMidpoint(void) { screenPt circPt; GLint xc = 0; GLint yc = 0; GLint radius = 50; GLint p = 1 - radius; // Initial value for midpiont parameter. circPt.setCoords(0, radius);// Set coords for top point of circle. void circlePlotPoints(GLint, GLint, screenPt); /* Plot the initial point in each circle quadrant. */ circlePlotPoints(xc, yc, circPt); /* Calculate next point and plot in each octant. */ while (circPt.getx()<circPt.gety()) { length++; circPt.incrementx(); if (p<0) p += 2 * circPt.getx() + 1; else { circPt.decrementy(); p += 2 * (circPt.getx() - circPt.gety()) + 1; } circlePlotPoints(xc, yc, circPt); } } int main(int argc, char *argv[]) { glutInit(&argc, argv);//初始化GULT glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);//设置显示模式 glutInitWindowPosition(300,500);//设置左上角窗口显示位置 glutInitWindowSize(400, 300);//设置窗口显示的宽与高 glutCreateWindow("中点画圆算法");//创建一个窗口 init();//执行初始化程序 circleMidpoint(); glutDisplayFunc(setPixel);//把图形显示在窗口 glutMainLoop();//显示所有并进入等待状态 }