在OpenGL中使用freeglut链接错误

Linking error in OpenGL using freeglut in CLion

本文关键字：freeglut 链接 错误 OpenGL      更新时间：2023-10-16

所以，我使用freeglut尝试做一些openGL的东西，但我不断得到错误说引用是未定义的:

CMakeFilestexture_mapping.dir/objects.a(TextureMapper.cpp.obj): In function `ZN13TextureMapper4initEv':
.../TextureMapper.cpp:20: undefined reference to `glClearColor@16'
.../TextureMapper.cpp:23: undefined reference to `glMatrixMode@4'
.../TextureMapper.cpp:24: undefined reference to `glLoadIdentity@0'
.../TextureMapper.cpp:25: undefined reference to `glOrtho@48'
CMakeFilestexture_mapping.dir/objects.a(TextureMapper.cpp.obj): In function `ZN13TextureMapper7displayEv':
.../TextureMapper.cpp:45: undefined reference to `glClear@4'
...TextureMapper.cpp:48: undefined reference to `glColor3f@12'
...TextureMapper.cpp:49: undefined reference to `glBegin@4'
...TextureMapper.cpp:52: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:53: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:54: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:55: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:58: undefined reference to `glEnd@0'
...TextureMapper.cpp:61: undefined reference to `glFlush@0'

我使用MinGW与CLion做这个项目。我以为我做对了。我将适当的文件移动到MinGW中的include文件夹，以及bin文件夹和lib文件夹。然后，我有这个在我的CMakeLists.txt:

cmake_minimum_required(VERSION 3.3)
project(texture_mapping)
find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(SOURCE_FILES main.cpp TextureMapper.cpp TextureMapper.h Vertex.h ObjParser.cpp ObjParser.h)
add_executable(texture_mapping ${SOURCE_FILES})
target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a)

我链接的库是freeglut附带的唯一库文件。

那么，我错过了什么?在编译之前，CLion不会显示任何错误。我甚至可以进入freeglut提供的头文件中的函数。那么，为什么这些函数没有在我的程序中定义?

我一直在努力解决同样的问题，并通过将以下行添加到CMakeLists.txt:

find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARY})

你实际上并没有将OpenGL链接到你的项目，所以你得到了对OpenGL函数的未定义引用。尝试替换

target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a)


target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a GL)

我用你的CMakeLists.txt和以下程序重现了你的问题:

#include <GL/gl.h>
int main() {
        glClear(GL_COLOR_BUFFER_BIT);
        return 0;
}

，并通过上述替换解决。该解决方案自动从我的库路径链接GL库:

$ ls -1 /usr/lib64/libGL.*
/usr/lib64/libGL.la
/usr/lib64/libGL.so
/usr/lib64/libGL.so.1
/usr/lib64/libGL.so.1.0.0

根据这个，你有一些变量来访问你实际的OpenGL库。例如，你可以像这样直接指向OpenGL库文件:

target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a ${OPENGL_gl_LIBRARY})

也可以将OpenGL库目录添加到库搜索路径中(在target_link_libraries之前):

link_directories(${OPENGL_gl_LIBRARY})

重新排序CMakeLists.txt对我有帮助(<name>应该相应地替换):

cmake_minimum_required(VERSION 3.10)
project(<name>)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lGL -lGLU -lglut")
set(CMAKE_CXX_STANDARD 17)
add_executable(<name> main.cpp)
find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARY})
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