OpenGL 橡皮筋技术

后天图形学考试，整理了下实验课上的OpenGL关于橡皮筋实验的代码。

 

简单实现了如下功能：

1.右键菜单功能响应

2.右键选择画折线或矩形，可保存（书上例子演变）

3.可选取画线或画矩形的颜色，线宽，像素大小

 

#include <gl/glut.h> #include <stdlib.h> #define NUM 100 //折线的最大折线段 int Flag = 0; //标记是否已经开始绘制折线 int RFlag = 0; //标记是否已经完成一个矩形 int Function = 1; //标记选择的功能是画折线还是矩形 int winWidth = 800, winHeight = 600; //窗口的宽度和高度 int Mousex, Mousey; //用于记录当前鼠标的位置 int n = 0; //用于记录折线有几段 int m = 0; //用于记录矩形个数 //线性结构体 struct LineNode { int x1; int y1; int x2; int y2; }Line[NUM]; //矩形结构体 struct Rectangle { int x1; int y1; int x2; int y2; }Rect[NUM]; static GLsizei iMode = 1; void Initial(void) { glClearColor(1.0f, 1.0f, 1.0f, 1.0f); //设置窗口背景颜色 } void ChangeSize(int w, int h) { //保存当前窗口的大小 winWidth = w; winHeight = h; glViewport(0, 0, w, h); //指定窗口显示区域 glMatrixMode(GL_PROJECTION); //指定设置投影参数 glLoadIdentity(); //调用单位矩阵，去掉以前的投影参数设置 gluOrtho2D(0.0, winWidth, 0.0, winHeight); //设置投影参数 } void ProcessMenu1(int value) { Function = value; //接收选择 n = 0; Flag = 0; m = 0; RFlag = 0; glutPostRedisplay(); } void ProcessMenu2(int value) { iMode = value; n = 0; Flag = 0; m = 0; RFlag = 0; glutPostRedisplay(); } void Display() { //默认画笔是红色，是线性模式，不填充 int i, j; glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); //线性模式画图 glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口 glColor3f(1.0f, 0.0f, 0.0f); //指定当前的绘图颜色 switch(iMode){case 3:glColor3f(1.0f, 0.0f, 0.0f); //红色 break;case 4:glColor3f(0.0f, 1.0f, 0.0f); //绿色 break;case 5:glColor3f(0.0f, 0.0f, 1.0f); //蓝色break;case 6:glColor3f(0.0f, 0.0f, 0.0f); //黑色 break;case 7:glLineWidth(2); //像素增大 break;case 8:glLineWidth(1); //像素减小break;case 9:glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); break;case 10:glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); //线性模式画图 break;case 11://退出exit(0);break;case 12://清屏glClear(GL_COLOR_BUFFER_BIT); //用当前背景色填充窗口 break;} if (Function == 1) { for (i = 0; i < n; i++) { glBegin(GL_LINES); //绘制直线段 glVertex2i(Line[i].x1, Line[i].y1); glVertex2i(Line[i].x2, Line[i].y2); glEnd(); } //动态绘制鼠标动作 if (Flag == 1) { glBegin(GL_LINES); glVertex2i(Line[i].x1, Line[i].y1); glVertex2i(Mousex, Mousey); glEnd(); } } else { //绘制矩形 for (j = 0; j < m; j++) { glRecti(Rect[j].x1, Rect[j].y1, Rect[j].x2, Rect[j].y2); } //动态绘制鼠标动作 if (RFlag == 1) { glRecti(Rect[j].x1, Rect[j].y1, Mousex, Mousey); } } glutSwapBuffers(); //交换缓冲区 } void MousePlot(GLint button, GLint action, GLint xMouse, GLint yMouse) { if (Function == 1) { if (button == GLUT_LEFT_BUTTON && action == GLUT_DOWN) { if (Flag == 0) { Flag = 1; Line[n].x1 = xMouse; Line[n].y1 = winHeight - yMouse; } else { Line[n].x2 = xMouse; Line[n].y2 = winHeight - yMouse; n++; //折线的第二点作为下一段线的第一个的点 Line[n].x1 = Line[n-1].x2; Line[n].y1 = Line[n-1].y2; } } } else { //矩形处理 if (button == GLUT_LEFT_BUTTON && action == GLUT_DOWN) { if (RFlag == 0) { RFlag = 1; Rect[m].x1 = xMouse; Rect[m].y1 = winHeight - yMouse; } else { RFlag = 0; Rect[m].x2 = xMouse; Rect[m].y2 = winHeight - yMouse; m++; glutPostRedisplay(); } } } } void PassiveMouseMove(GLint xMouse, GLint yMouse) { Mousex = xMouse; Mousey = winHeight - yMouse; glutPostRedisplay(); } int main(int argc, char *argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); //使用双缓存及RGB模型 glutInitWindowSize(400, 300); //指定窗口的尺寸 glutInitWindowPosition(100, 100); //指定窗口在屏幕上的位置 glutCreateWindow("橡皮筋技术"); int nFunctionMenu=glutCreateMenu(ProcessMenu1); glutAddMenuEntry("画折线", 1); glutAddMenuEntry("画矩形", 2); int nColorMenu = glutCreateMenu(ProcessMenu2); glutAddMenuEntry("Red",3); //创建右键颜色菜单glutAddMenuEntry("Green",4);glutAddMenuEntry("Blue",5);glutAddMenuEntry("Black",6);int nPixelMenu = glutCreateMenu(ProcessMenu2); //创建右键像素菜单glutAddMenuEntry("increase pixel size",7);glutAddMenuEntry("decrease pixel size",8);int nFilleMenu = glutCreateMenu(ProcessMenu2); //创建右键填充菜单glutAddMenuEntry("fill on",9);glutAddMenuEntry("fill off",10);int nMainMenu = glutCreateMenu(ProcessMenu2);glutAddSubMenu("功能",nFunctionMenu);glutAddSubMenu("颜色", nColorMenu);glutAddSubMenu("像素大小", nPixelMenu);glutAddSubMenu("填充", nFilleMenu); glutAttachMenu(GLUT_RIGHT_BUTTON); //右键glutCreateMenu(ProcessMenu2); glutAddMenuEntry("退出", 11);glutAddMenuEntry("清屏", 12); glutAttachMenu(GLUT_MIDDLE_BUTTON); //中间键 glutDisplayFunc(Display); glutReshapeFunc(ChangeSize); //指定窗口再整形回调函数 glutMouseFunc(MousePlot); //指定鼠标响应函数 glutPassiveMotionFunc(PassiveMouseMove); //指定鼠标移动响应函数 Initial(); glutMainLoop(); //启动主GLUT事件处理循环 return 0; }