下面的程序中有什么错误

Question

我正在尝试使用命令gcc -lGL -lglut ex2_6.c -o ex2_6编译它。下面给出了错误。我在这个链接上的链接http://www.glprogramming.com/red/chapter02.html.See example 2-6中获得了这个代码。

hemkar@ubuntu:~$ gcc -lGL -lglut ex2_6.c -o ex2_6
/tmp/ccrgl3Y9.o:ex2_6.c:function reshape: error: undefined reference to 'gluOrtho2D' collect2: ld returned 1 exit status 

代码：

#include <GL/gl.h>
#include <GL/glut.h>

void display(void)
{
   GLubyte fly[] = {
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x03, 0x80, 0x01, 0xC0, 0x06, 0xC0, 0x03, 0x60, 
      0x04, 0x60, 0x06, 0x20, 0x04, 0x30, 0x0C, 0x20, 
      0x04, 0x18, 0x18, 0x20, 0x04, 0x0C, 0x30, 0x20,
      0x04, 0x06, 0x60, 0x20, 0x44, 0x03, 0xC0, 0x22, 
      0x44, 0x01, 0x80, 0x22, 0x44, 0x01, 0x80, 0x22, 
      0x44, 0x01, 0x80, 0x22, 0x44, 0x01, 0x80, 0x22,
      0x44, 0x01, 0x80, 0x22, 0x44, 0x01, 0x80, 0x22, 
      0x66, 0x01, 0x80, 0x66, 0x33, 0x01, 0x80, 0xCC, 
      0x19, 0x81, 0x81, 0x98, 0x0C, 0xC1, 0x83, 0x30,
      0x07, 0xe1, 0x87, 0xe0, 0x03, 0x3f, 0xfc, 0xc0, 
      0x03, 0x31, 0x8c, 0xc0, 0x03, 0x33, 0xcc, 0xc0, 
      0x06, 0x64, 0x26, 0x60, 0x0c, 0xcc, 0x33, 0x30,
      0x18, 0xcc, 0x33, 0x18, 0x10, 0xc4, 0x23, 0x08, 
      0x10, 0x63, 0xC6, 0x08, 0x10, 0x30, 0x0c, 0x08, 
      0x10, 0x18, 0x18, 0x08, 0x10, 0x00, 0x00, 0x08};
   GLubyte halftone[] = {
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55,
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55,
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55,
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55,
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55, 
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55,
      0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55, 0x55, 0x55};

   glClear (GL_COLOR_BUFFER_BIT);
   glColor3f (1.0, 1.0, 1.0);

/*  draw one solid, unstippled rectangle,       */      
/*  then two stippled rectangles                */
   glRectf (25.0, 25.0, 125.0, 125.0);
   glEnable (GL_POLYGON_STIPPLE);
   glPolygonStipple (fly);
   glRectf (125.0, 25.0, 225.0, 125.0);
   glPolygonStipple (halftone);
   glRectf (225.0, 25.0, 325.0, 125.0);
   glDisable (GL_POLYGON_STIPPLE);

   glFlush ();
}

void init (void) 
{
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel (GL_FLAT);    
}

void reshape (int w, int h)
{
   glViewport (0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity ();
   gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize (350, 150);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutMainLoop();
   return 0;  
}

Answer 1

您正在尝试使用没有链接到OpenGL Utility Library的gluOrtho2D()。

试试这个：

gcc ex2_6.c -o ex2_6 -lGL -lglut -lGLU

或者改用glOrtho()来回避整个问题。

Answer 2

库链接器标志需要放在末尾：

cc -o foo foo.c -lGL -lglut