c++ - 使用 SDL 和 GLEW 设置 Visual Studio 项目

Question

我刚开始使用 Visual Studio 以及库 OpenGL 和 SDL。

我在设置我的程序时遇到问题，并且在我尝试构建它时不断遇到错误。

任何人都可以帮我解决以下问题 -

Error   1   error LNK2019: unresolved external symbol __imp__glewInit@0 referenced in function _SDL_main    
Error   2   error LNK2019: unresolved external symbol __imp__glewGetErrorString@4 referenced in function _SDL_main  
Error   3   error LNK2001: unresolved external symbol __imp____GLEW_VERSION_3_0 
Error   4   error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup   
Error   5   error LNK1120: 4 unresolved externals   
    6   IntelliSense: identifier "GLuint" is undefined  
    7   IntelliSense: identifier "GLuint" is undefined  

这是我的代码-

主.c

#include<SDL.h>
#include<GL\glew.h>
#include <stdio.h>

char shouldExit = 0;
int main(void)
{
    /* Initialize SDL *l
    if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) {
    return 1;
    }
    /* Create the window, OpenGL context */
    SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_Window* window = SDL_CreateWindow(
        "TestSDL",
        SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
        640, 480,
        SDL_WINDOW_OPENGL);
    if (!window) {
        fprintf(stderr, "Could not create window.ErrorCode = %s\n", SDL_GetError());
        SDL_Quit();
        return 1;
    }
    SDL_GL_CreateContext(window);
    /* Make sure we have a recent version of OpenGL */
    GLenum glewError = glewInit();
    if (glewError != GLEW_OK) {
        fprintf(stderr, "Could not initialize glew.ErrorCode = %s\n", glewGetErrorString(glewError));
        SDL_Quit();
        return 1;
    }
    if (!GLEW_VERSION_3_0) {
        fprintf(stderr, "OpenGL max supported version is too low.\n");
        SDL_Quit();
        return 1;
    }
    /* Setup OpenGL state */
    glViewport(0, 0, 640, 480);
    glMatrixMode(GL_PROJECTION);
    glOrtho(0, 640, 480, 0, 0, 100);
    glEnable(GL_TEXTURE_2D);
    /* The game loop */
    while (!shouldExit) {
        // Handle OS message pump
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
            case SDL_QUIT:
                shouldExit = 1;
            }
        }
        glClearColor(0, 0, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT);
        /* Game logic goes here */
        SDL_GL_SwapWindow(window);
    }
    SDL_Quit();
    return 0;
}

DrawUtils.c

/***********************************************************************
 Utilities for loading and drawing sprites.
*/
#include<GL/glew.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>

/* Load a file into an OpenGL texture, and return that texture. */
GLuint glTexImageTGAFile( const char* filename, int* outWidth, int* outHeight )
{
    const int BPP = 4;

    /* open the file */
    FILE* file = fopen( filename, "rb" );
    if( file == NULL ) {
        fprintf( stderr, "File: %s -- Could not open for reading.\n", filename );
        return 0;
    }

    /* skip first two bytes of data we don't need */
    fseek( file, 2, SEEK_CUR );

    /* read in the image type.  For our purposes the image type should
     * be either a 2 or a 3. */
    unsigned char imageTypeCode;
    fread( &imageTypeCode, 1, 1, file );
    if( imageTypeCode != 2 && imageTypeCode != 3 ) {
        fclose( file );
        fprintf( stderr, "File: %s -- Unsupported TGA type: %d\n", filename, imageTypeCode );
        return 0;
    }

    /* skip 9 bytes of data we don't need */
    fseek( file, 9, SEEK_CUR );

    /* read image dimensions */
    int imageWidth = 0;
    int imageHeight = 0;
    int bitCount = 0;
    fread( &imageWidth, sizeof( short ), 1, file );
    fread( &imageHeight, sizeof( short ), 1, file );
    fread( &bitCount, sizeof( unsigned char ), 1, file );
    fseek( file, 1, SEEK_CUR );

    /* allocate memory for image data and read it in */
    unsigned char* bytes = (unsigned char*)calloc( imageWidth * imageHeight * BPP, 1 );

    /* read in data */
    if( bitCount == 32 ) {
        int it;
        for( it = 0; it != imageWidth * imageHeight; ++it ) {
            bytes[ it * BPP + 0 ] = fgetc( file );
            bytes[ it * BPP + 1 ] = fgetc( file );
            bytes[ it * BPP + 2 ] = fgetc( file );
            bytes[ it * BPP + 3 ] = fgetc( file );
        }
    } else {
        int it;
        for( it = 0; it != imageWidth * imageHeight; ++it ) {
            bytes[ it * BPP + 0 ] = fgetc( file );
            bytes[ it * BPP + 1 ] = fgetc( file );
            bytes[ it * BPP + 2 ] = fgetc( file );
            bytes[ it * BPP + 3 ] = 255;
        }
    }

    fclose( file );

    /* load into OpenGL */
    GLuint tex;
    glGenTextures( 1, &tex );
    glBindTexture( GL_TEXTURE_2D, tex );
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, imageWidth, imageHeight, 0,
                  GL_BGRA, GL_UNSIGNED_BYTE, bytes );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );

    free( bytes );

    if( outWidth ) {
        *outWidth = imageWidth;
    }
    if( outHeight ) {
        *outHeight = imageHeight;
    }
    return tex;
}

/* Draw the sprite */
void glDrawSprite( GLuint tex, int x, int y, int w, int h )
{
    glBindTexture( GL_TEXTURE_2D, tex );
    glBegin( GL_QUADS );
    {
    glColor3ub( 255, 255, 255 );
    glTexCoord2f( 0, 1 );
    glVertex2i( x, y );
    glTexCoord2f( 1, 1 );
    glVertex2i( x + w, y );
    glTexCoord2f( 1, 0 );
    glVertex2i( x + w, y + h );
    glTexCoord2f( 0, 0 );
    glVertex2i( x, y + h );
    }
    glEnd();
}

DrawUtils.h

#ifndef DRAWUTILS_H
#define DRAWUTILS_H

#ifdef __cplusplus
extern "C" {
#endif

GLuint glTexImageTGAFile( const char* filename, int* outWidth, int* outHeight );
void glDrawSprite( GLuint tex, int x, int y, int w, int h );

#ifdef __cplusplus
}
#endif

#endif

我是否缺少#include？

Answer 1

不，你错过了一个图书馆。您包括 GLEW 头文件:

#include<GL\glew.h>

但是，头文件仅定义函数原型(prototype)(例如glewInit())——这些函数的实际实现将被存储在 .lib(或 .a)文件中，您必须链接该文件才能构建项目。

我已经有一段时间没有使用 Visual Studio 了，但我认为您通常会将链接器选项设置为项目配置的一部分。但是，可以在您的代码中指定链接器选项，如果您必须:

#pragma comment(lib, "glew/glew32s.lib")

请注意，#pragma 方法是特定于 MSVC 的，可能不适用于其他编译器。

如果您不愿意摆弄链接器选项，您可以随时使用 add glew.c to your project相反。

---

另一件事:您在 DrawUtils.h 中使用 GLuint，但没有包含 gl.h 或 glew.h :

GLuint glTexImageTGAFile( const char* filename, int* outWidth, int* outHeight );
void glDrawSprite( GLuint tex, int x, int y, int w, int h );