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STL map issue

Started by chikinpotpi Mar 28, 2009 at 4:13 PM 1 replies 600+ views

Original Post

Mar 28, 2009 at 4:13 PM

I am a C# .NET programmer who has recently switched to c++, and thus my understanding on some things could be a little fuzzy... i am attempting to create a static STL map for the purpose of keeping track of which textures i have already loaded into video memory. It needs to store a string, and a GLuint, and after reading some things i managed to get that working, but when i tried to make it a static member of my texture loading class, everything goes haywire... so here is my code, and my error, any help would be greatly appreciated... Header: #ifndef __TEXTURELOADER_H__ #define __TEXTURELOADER_H__ #include #include #include #include #include #include #include #include "TGAHeader.h" #include "Texture.h" #include "TGA.h" class TextureLoader { private: static bool LoadTGA(Texture * texture, const char * filename); static bool LoadUncompressedTGA(Texture *, const char * filename, FILE *); static bool LoadCompressedTGA(Texture *, const char * filename, FILE *); static std::map textures; public: static GLuint LoadTexture(std::string filename); }; #endif code for LoadTexture (this is where the error occurs i think) : GLuint TextureLoader::LoadTexture(std::string filename) { Texture tex; //create Texture structure to load into GLuint texID; //greate ID for texture once loaded in OpenGL if(textures.find(filename) != textures.end()) { return textures.find(filename)->second; } if(LoadTGA(&tex, filename.c_str())) //Try to load texture from file, if sccuessful, load into OpenGl { glGenTextures(1, &texID); glBindTexture(GL_TEXTURE_2D, texID); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); glTexImage2D(GL_TEXTURE_2D, 0, 4, tex.width, tex.height, 0, tex.type, GL_UNSIGNED_BYTE, tex.imageData); } free(tex.imageData); textures[filename] = texID; return texID; //return OpenGl Texture ID so that we can use it } All the code compiles fine, and the application launches, but then i get this: ZeroLink: unknown symbol '__ZN13TextureLoader8texturesE' SimpleGame has exited due to signal 6 (SIGABRT). Again, my "c++-fu" is very weak so this could be something very simple... Thanks for taking the time to read!!

Antheus

216

Antheus

Mar 28, 2009 at 4:24 PM

When a static member is declared, it's shared by all instances. It's up to you to specify where it's allocated.

static std::map<std::string, GLuint> textures;

means simply that there exists textures member, but it doesn't say where. That's up to linker to determine.

So somewhere (usually in accompanying cpp file), such member is defined.
Basically:

std::map<std::string, GLuint> TextureLoader::textures;

Also [ source ] or [ code ] tags make things more readable.

chikinpotpi

Author

chikinpotpi

Mar 28, 2009 at 5:42 PM

Thanks for the reply!!

That was spot on and very insightful!

Its amazing the things you don't learn when Visual Studio writes half your code for you...

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