Opengl linux 未定义对基本函数的引用 [英] Opengl linux undefined reference to basic functions

问题描述

我在 Ubuntu 11.04 上编写了一个使用 freeglut 的程序.它工作得很好.然后我得到了另一台计算机并尝试在全新安装的 Ubuntu 11.04 上运行该程序.不起作用.所以我安装了

I wrote a program on Ubuntu 11.04 that uses freeglut. It worked fine. Then I got another computer and tried to run the program on a fresh install of Ubuntu 11.04. Doesn't work. So I installed

sudo apt-get install freeglut3 freeglut3-dev libglew1.5 libglew1.5-dev libglu1-mesa libglu1-mesa-dev libgl1-mesa-glx libgl1-mesa-dev mesa-common-dev gcc

sudo apt-get install freeglut3 freeglut3-dev libglew1.5 libglew1.5-dev libglu1-mesa libglu1-mesa-dev libgl1-mesa-glx libgl1-mesa-dev mesa-common-dev gcc

并尝试运行导入的程序

    #include <GL/freeglut.h>
    #include <GL/gl.h>
    #include <GL/glu.h>

使用命令

g++ -lGL -lGLU -lglut Driver.cpp -o a

但是链接器或其他任何东西会吐出 200 个表单错误:

However the linker or whatever spits out like 200 errors of the form:

    Driver.cpp:(.text+0x3c6b): undefined reference to `glutSolidSphere'
    Driver.cpp:(.text+0x3c75): undefined reference to `glEnable'
    Driver.cpp:(.text+0x3c9a): undefined reference to `glColor4f'
    Driver.cpp:(.text+0x3cb5): undefined reference to `glRotatef'
    Driver.cpp:(.text+0x3d02): undefined reference to `glutSolidSphere'
    Driver.cpp:(.text+0x3d07): undefined reference to `glutSwapBuffers'

问题的原因是什么?

推荐答案

指定要链接到的对象(包括静态和动态库)的顺序很重要.

The order in which you specify the objects you want to link to (including static and dynamic libraries) can matter.

尝试:

g++ Driver.cpp -lGL -lGLU -lglut  -o a

(不确定库的顺序，但看起来没问题.)

(Not sure about the order of the libs, but that looks ok.)

构建命令行时的想法是，如果a 需要来自b 的符号，b 必须出现在之后 a 在命令行中.

The idea when you build your command line is that if a requires a symbol from b, b must appear after a in the command line.

共享库的 GCC/ld 发生(或不发生)链接顺序问题取决于(很可能在其他方面 - 我不是这里的专家)是否 --as-needed 链接标志是否设置.(例如，参见 Gentoo 的 as-needed 转换中的最后一项指南.)
当 --as-needed 处于活动状态时，链接过程会尽快消除不需要的符号，如果链接顺序不正确"，则会导致问题.这样做是为了减少最终可执行文件中存在的不必要依赖项的数量.
如果 --as-needed 未处于活动状态，则不会(或更少)发生这种情况 - 所有符号都保留在这种情况下，并且链接顺序无关紧要(或多或少 - 再次，我不是专家.)

The link order problem happens (or not) with GCC/ld for shared libraries depending on (most likely among other things - I'm no expert here) whether the --as-needed link flag is set or not. (See for instance the before-last item in Gentoo's as-needed transition guide.)
The linking process eliminates un-needed symbols ASAP when --as-needed is active, which causes problems if the link order is not "correct". This is done to reduce the number of un-necessary dependencies present in final executables.
This doesn't happen (or less so) if --as-needed is not active - all symbols are kept in that case, and link order doesn't matter as much (more or less - again, I'm no expert.)

由于不同的发行版对该标志使用不同的默认值，GCC 的行为可能看起来不一致，但这只是一种印象.

Since different distributions use different defaults for that flag, the behavior of GCC might seem inconsistent, but that's just an impression.

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