c++ - 错误 LNK2019 : unresolved external symbol

Question

当我想编译我的 opengl 代码时，出现以下错误:

Error   1   error LNK2019: unresolved external symbol __imp__glewInit@0 
Error   2   error LNK2019: unresolved external symbol __imp__glewGetErrorString@4 
Error   3   error LNK2001: unresolved external symbol __imp____glewAttachShader     
Error   4   error LNK2001: unresolved external symbol __imp____glewCompileShader    
Error   5   error LNK2001: unresolved external symbol __imp____glewCreateProgram    
Error   6   error LNK2001: unresolved external symbol __imp____glewCreateShader 
Error   7   error LNK2001: unresolved external symbol __imp____glewDeleteProgram    
Error   8   error LNK2001: unresolved external symbol __imp____glewDisableVertexAttribArray 
Error   9   error LNK2001: unresolved external symbol __imp____glewEnableVertexAttribArray  
Error   10  error LNK2001: unresolved external symbol __imp____glewGetAttribLocation    
Error   11  error LNK2001: unresolved external symbol __imp____glewGetProgramiv 
Error   12  error LNK2001: unresolved external symbol __imp____glewGetShaderiv  
Error   13  error LNK2001: unresolved external symbol __imp____glewLinkProgram  
Error   16  error LNK2001: unresolved external symbol __imp____glewVertexAttribPointer  
Error   17  error LNK1120: 16 unresolved externals  

我的代码是:

#include <Windows.h>
#include <iostream>
#include <glew.h>
#include <gl\GL.h>
#include <freeglut.h>

using namespace std;

GLuint program;
GLint attribute_coord2d;

int init_resources(void)
{
  GLint compile_ok = GL_FALSE, link_ok = GL_FALSE;

  GLuint vs = glCreateShader(GL_VERTEX_SHADER);
  const char *vs_source = 
#ifdef GL_ES_VERSION_2_0
    "#version 100\n"  // OpenGL ES 2.0
#else 
    "#version 120\n"  // OpenGL 2.1
#endif
    "attribute vec2 coord2d;                  "
    "void main(void) {                        "
    "  gl_Position = vec4(coord2d, 0.0, 1.0); "
    "}";
  glShaderSource(vs, 1, &vs_source, NULL);
  glCompileShader(vs);
  glGetShaderiv(vs, GL_COMPILE_STATUS, &compile_ok);
  if (0 == compile_ok)
  {
    fprintf(stderr, "Error in vertex shader\n");
    return 0;
  }

   GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
  const char *fs_source =
    "#version 120           \n"
    "void main(void) {        "
    "  gl_FragColor[0] = 0.0; "
    "  gl_FragColor[1] = 0.0; "
    "  gl_FragColor[2] = 1.0; "
    "}";
  glShaderSource(fs, 1, &fs_source, NULL);
  glCompileShader(fs);
  glGetShaderiv(fs, GL_COMPILE_STATUS, &compile_ok);
  if (!compile_ok) {
    fprintf(stderr, "Error in fragment shader\n");
    return 0;
  }

   program = glCreateProgram();
  glAttachShader(program, vs);
  glAttachShader(program, fs);
  glLinkProgram(program);
  glGetProgramiv(program, GL_LINK_STATUS, &link_ok);
  if (!link_ok) {
    fprintf(stderr, "glLinkProgram:");
    return 0;
  }

    const char* attribute_name = "coord2d";
  attribute_coord2d = glGetAttribLocation(program, attribute_name);
  if (attribute_coord2d == -1) {
    fprintf(stderr, "Could not bind attribute %s\n", attribute_name);
    return 0;
  }

  return 1;
}

void onDisplay()
{
  /* Clear the background as white */
  glClearColor(1.0, 1.0, 1.0, 1.0);
  glClear(GL_COLOR_BUFFER_BIT);

  glUseProgram(program);
  glEnableVertexAttribArray(attribute_coord2d);
  GLfloat triangle_vertices[] = {
     0.0,  0.8,
    -0.8, -0.8,
     0.8, -0.8,
  };
  /* Describe our vertices array to OpenGL (it can't guess its format automatically) */
  glVertexAttribPointer(
    attribute_coord2d, // attribute
    2,                 // number of elements per vertex, here (x,y)
    GL_FLOAT,          // the type of each element
    GL_FALSE,          // take our values as-is
    0,                 // no extra data between each position
    triangle_vertices  // pointer to the C array
  );

  /* Push each element in buffer_vertices to the vertex shader */
  glDrawArrays(GL_TRIANGLES, 0, 3);
  glDisableVertexAttribArray(attribute_coord2d);
 
  /* Display the result */
  glutSwapBuffers();
}

void free_resources()
{
  glDeleteProgram(program);
}


int main(int argc, char* argv[])
{
  /* Glut-related initialising functions */
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
  glutInitWindowSize(640, 480);
  glutCreateWindow("My First Triangle");

  /* Extension wrangler initialising */
  GLenum glew_status = glewInit();
  if (glew_status != GLEW_OK)
  {
    fprintf(stderr, "Error: %s\n", glewGetErrorString(glew_status));
    return EXIT_FAILURE;
  }

  /* When all init functions runs without errors,
  the program can initialise the resources */
  if (1 == init_resources())
  {
    /* We can display it if everything goes OK */
    glutDisplayFunc(onDisplay);
    glutMainLoop();
  }

  /* If the program exits in the usual way,
  free resources and exit with a success */
  free_resources();
  return EXIT_SUCCESS;
}

我尝试了所有方法，包括显式调整链接器选项(包括 .lib 文件)、指定包含与这些错误相关的阅读论坛的路径等等，但都没有帮助，你们能帮我解决这个问题吗？

Answer 1

我从 http://glew.sourceforge.net/index.html 得到了 glew 二进制文件( https://sourceforge.net/projects/glew/files/glew/1.9.0/glew-1.9.0-win32.zip/download ) 和来自 http://www.transmissionzero.co.uk/software/freeglut-devel/ 的 freeglut 2.8.0 MSVC 包( http://files.transmissionzero.co.uk/software/development/GLUT/freeglut-MSVC.zip )

我将包含路径设置为 glew-1.9.0\include\ , freeglut\include\和库路径 freeglut\lib\ , glew-1.9.0\lib\ .

我将您的文件标题更正为

#include <Windows.h>
#include <iostream>
#include <gl/glew.h>
#include <gl/GL.h>
#include <gl/freeglut.h>

#pragma comment(lib, "glew32.lib")

链接成功，成功。

UPD

使用第三方库时，通常:

• 您必须将包含路径设置为 <3rdPartyDir>\include , 但不是 <3rdPartyDir>\include\lib_name .在源代码中声明它应该是:

正确:#include <lib_name/header_name.h>

错误:#include <header_name.h> ，因为在库中可以是内部依赖项，例如 #include <lib_name/other_header_name.h>

• 将库路径设置为<3rdPartyDir>\lib .然后，您必须指定所需的库，可以使用以下方法之一:

对于 MSVC，添加

#ifdef _MSC_VER
#pragma comment(lib, "lib1_name.lib")
#pragma comment(lib, "lib2_name.lib")
/// etc
#endif

或者，将所需的库添加到链接器选项。

一些库支持自动链接机制(例如，freeglut)，即头文件包含类似#pragma comment(lib, "lib1_name.lib") 的行

• 从 <3rdPartyDir>\bin 复制所需的 dll至 <MyExePath>\