OPENGL鼠标拾取与选择

//该程序完成的功能是：绘制9个方块，鼠标左键点击，改变方块的颜色 #include <gl/glut.h> #include<iostream> #include<vector> using namespace std; int board[3][3]; //存储几个方块的颜色 #define BUFSIZE 512 //处理点击记录: //hits为产生的点击的数量，buffer中存储点击记录，每个点击记录由四个项目组成 void processHits(GLint hits, GLuint buffer[]) { unsigned int i, j; GLuint ii, jj, names, *ptr; vector<int> n; ptr = (GLuint *)buffer; for (i = 0; i < hits; i++) { names = *ptr; cout << "the name_num = " << names << endl; ptr += 3; for (j = 0; j < names; j++) { n.push_back(*ptr); ptr++; } } if (n.size() > 0) { cout << "茶壶标号"; for (int k = 0; k < n.size(); k++) cout << n[k]; cout << endl; } } //绘制所有方块，参数有GL_RENDER和GL_SELECT两种模式 void drawSquares(GLenum mode) { //设置清除屏幕的颜色，并清除屏幕和深度缓冲 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //设置成模型矩阵模式 glMatrixMode(GL_MODELVIEW); //载入单位化矩阵 glLoadIdentity(); //坐标中心向Z轴平移-G_fDistance (使坐标中心位于摄像机前方) glTranslatef(0.0, 0.0, -3.0); //////////////////////////////////////////////// //绘制物体 //glInitNames(); //初始化名字堆栈并压入初始元素 //if (mode == GL_SELECT) // glPushName(1); //glutWireTeapot(0.3); //if (mode == GL_SELECT) //弹出名字 // glPopName(); //glTranslatef(1, 0, 0); //if (mode == GL_SELECT) //将y方向上的索引压入名字堆栈 // glPushName(2); //glutWireTeapot(0.3); //if (mode == GL_SELECT) //弹出名字 // glPopName(); //glTranslatef(0, 1, 0); //if (mode == GL_SELECT) //将y方向上的索引压入名字堆栈 // glPushName(3); //glutWireTeapot(0.3); //if (mode == GL_SELECT) //弹出名字 // glPopName(); glInitNames(); glPushName(0); for (int i = 0; i < 2; i++) { if (mode == GL_SELECT) glLoadName(i); for (int j = 0; j < 2; j++) { glPushMatrix(); glTranslatef(i, j, 0); if (mode == GL_SELECT) //将y方向上的索引压入名字堆栈 glPushName(j); glutWireTeapot(0.3); //glutSolidSphere(0.2, 16, 16); if (mode == GL_SELECT) //弹出名字 glPopName(); glPopMatrix(); } } //交换前后缓冲区 glutSwapBuffers(); // glFlush(); } //当鼠标左键点击窗口时，进入选择模式开始绘制；绘制之后，处理点击记录 void pickSquares(int button, int state, int x, int y) { GLuint selectBuf[BUFSIZE]; //存储点击记录 GLint hits; //点击记录的个数 GLint viewport[4]; //视口 if (button != GLUT_LEFT_BUTTON || state != GLUT_DOWN) return; glGetIntegerv(GL_VIEWPORT, viewport); //获得视口 glSelectBuffer(BUFSIZE, selectBuf); //指定存储点击记录的数组 glRenderMode(GL_SELECT); //进入选择模式 glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); //设置挑选矩阵，挑选区域的中心坐标是(x,viewport[3]-y)，大小是(5,5) gluPickMatrix((GLdouble)x, (GLdouble)(viewport[3] - y), 5.0, 5.0, viewport); //设置投影矩阵 //gluOrtho2D(0.0, 3.0, 0.0, 3.0); gluPerspective(60.0f, float(viewport[2]) / float(viewport[3]), 1.0f, 1000.0f); //gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); //在选择模式下绘制方块 drawSquares(GL_SELECT); glMatrixMode(GL_PROJECTION); glPopMatrix(); glFlush(); //绘制结束 hits = glRenderMode(GL_RENDER); //获取记录下的点击的个数 processHits(hits, selectBuf); //处理点击记录selectBuf glutPostRedisplay(); } void init() { glEnable(GL_DEPTH_TEST); glShadeModel(GL_FLAT); for (int i = 0; i < 3; i++) //初始化9个方块的颜色 for (int j = 0; j < 3; j++) board[i][j] = 0; } void display() { glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); drawSquares(GL_RENDER); //基本绘制 //gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); glFlush(); } void reshape(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); /*gluOrtho2D(0.0, 3.0, 0.0, 3.0);*/ gluPerspective(60.0f, float(w) / float(h), 1.0f, 1000.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } int main(int argc, char ** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(600, 600); glutInitWindowPosition(100, 100); glutCreateWindow("pick"); init(); glutMouseFunc(pickSquares); //当鼠标点击时，调用pickSquares，进入选择模式进行绘制 glutReshapeFunc(reshape); glutDisplayFunc(display); //display只完成基本的绘制 glutMainLoop(); return 0; }