链接 openGL 库失败，因为它无法打开 libgl.so ... 但它就在那里

Question

当我尝试使用 openGL 制作一个我一直难以捉摸的 c++ 项目时，我遇到了以下错误。当我运行 make 文件时，我得到以下信息：

g++ -c init.cpp
g++ -o executable console.o init.o -lglut -lgl
/usr/bin/x86_64-linux-gnu-ld: cannot find -lgl
collect2: error: ld returned 1 exit status
Makefile:4: recipe for target 'all' failed
make: *** [all] Error 1

好的，当然。它没有找到图书馆。我将此行添加到我的 makefile 中以进行调查

ld -lglut -lgl --verbose

除此之外，我还得到了以下内容

attempt to open //usr/local/lib/x86_64-linux-gnu/libglut.so failed
attempt to open //usr/local/lib/x86_64-linux-gnu/libglut.a failed
attempt to open //lib/x86_64-linux-gnu/libglut.so failed
attempt to open //lib/x86_64-linux-gnu/libglut.a failed
attempt to open //usr/lib/x86_64-linux-gnu/libglut.so succeeded
-lglut (//usr/lib/x86_64-linux-gnu/libglut.so)
attempt to open //usr/local/lib/x86_64-linux-gnu/libgl.so failed
attempt to open //usr/local/lib/x86_64-linux-gnu/libgl.a failed
attempt to open //lib/x86_64-linux-gnu/libgl.so failed
attempt to open //lib/x86_64-linux-gnu/libgl.a failed
attempt to open //usr/lib/x86_64-linux-gnu/libgl.so failed
attempt to open //usr/lib/x86_64-linux-gnu/libgl.a failed
attempt to open //usr/lib/x86_64-linux-gnu64/libgl.so failed
attempt to open //usr/lib/x86_64-linux-gnu64/libgl.a failed
attempt to open //usr/local/lib64/libgl.so failed
attempt to open //usr/local/lib64/libgl.a failed
attempt to open //lib64/libgl.so failed
attempt to open //lib64/libgl.a failed
attempt to open //usr/lib64/libgl.so failed
attempt to open //usr/lib64/libgl.a failed
attempt to open //usr/local/lib/libgl.so failed
attempt to open //usr/local/lib/libgl.a failed
attempt to open //lib/libgl.so failed
attempt to open //lib/libgl.a failed
attempt to open //usr/lib/libgl.so failed
attempt to open //usr/lib/libgl.a failed
attempt to open //usr/x86_64-linux-gnu/lib64/libgl.so failed
attempt to open //usr/x86_64-linux-gnu/lib64/libgl.a failed
attempt to open //usr/x86_64-linux-gnu/lib/libgl.so failed
attempt to open //usr/x86_64-linux-gnu/lib/libgl.a failed
ld: cannot find -lgl
Makefile:4: recipe for target 'all' failed
make: *** [all] Error 1

所以当我在网上查看时，这些错误中的大部分似乎都与 ld 没有查找正确的目录有关，但是 ld 正在查找正确的目录，因为这种尝试实际上针对的是正确的位置：

attempt to open //usr/lib/x86_64-linux-gnu/libgl.so failed

Not only do I have the file in that directory, but it was last read from at 8:00, 3 hours ago because I was able to link it earlier somehow even though I haven't changed anything related to linking

这是我正在使用的生成文件。

cc=g++

edit: init.o console.o
    ld -lglut -lgl --verbose
    $(cc) -o executable console.o init.o -lglut -lgl

init.o: init.cpp
    $(cc) -c init.cpp

console.o: console.cpp
     $(cc) -c console.cpp

clean:
    rm init.o console.o executable

这里是 init.cpp:

#include <cstdlib>
//#include </usr/include/GL/glew.h>
#include <GL/freeglut.h>
//#include <GL/gl.h>
void consoleDisplay(int a);
void renderCB(void);
void resizeCB(int W, int H);
void idleCB(void);
void timerCB(int Value);
void glutInitErrorFunc(void (*callback)(const char *fmt, va_list ap) );
void glutInitWarningFunc(void (*callback)(const char *fmt, va_list ap) );
int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitContextVersion(4, 0);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(300, 300);
    int windowLeft= glutGet(GLUT_WINDOW_X);
    int windowWidth= glutGet(GLUT_WINDOW_WIDTH);
    consoleDisplay(windowLeft);
    consoleDisplay(windowWidth);
    int winID = glutCreateWindow("Hello again, world.");
    glutReshapeFunc(resizeCB);
    glutDisplayFunc(renderCB);
    glutIdleFunc(idleCB);
    glutTimerFunc(0, timerCB ,0);
    glutMainLoop();
    return 0;
}
void renderCB(void){
    //doActualOpenGLStuffHere()
    glutSwapBuffers();
    glutPostRedisplay();
}

void resizeCB(int W, int H){
    glViewport(0, 0, W, H);
}

void idleCB(void){
    glutPostRedisplay();
}

void timerCB(int Value){
}

最后 console.cpp:

#include <iostream>
void consoleDisplay(int a){
    std::cout << a << "\n";
}

Answer 1

大多数 Linux 文件系统是 case-sensitive 所以当你在系统库目录中有一个 libGL.so 并且 ld 询问文件系统是否存在 libgl.so它会拒绝并且链接会失败。

解决方案：确保您传递给 ld 的库名称与磁盘上的大小写相匹配：

$(cc) -o executable console.o init.o -lglut -lGL
                                              ^^ note the caps

链接 openGL 库失败，因为它无法打开 libgl.so ... 但它就在那里

Linking an openGL library fails because it can't open libgl.so ... but it's right there

c++

opengl

makefile

g++

ld