Question

我围绕OpenGL制作了一个小框架来创建一个简单的2D游戏。当我完成我的Texture类并在我的引擎Thogl（Orthogonal OpenGL）类中使用它我有很多无法解释的错误，这些错误没有用。我试图找到它，但我无法弄明白，我希望你们能帮我。我正在使用这些库：GLEW，GLFW，OpenGL32，GLM。

我的代码

Texture.h

#pragma once

#include <Magick++.h>
#include "Thogl.h"

class Texture
{
public:
    Texture(GLenum textureTarget);
    ~Texture();

    bool LoadImage(const char* fileName);

    void Bind(GLenum textureUnit);

    Magick::Image* image;

private:
    Magick::Blob blob;

    GLuint textureObject;
    GLenum textureTarget;
};

Texture.cpp

#include "Texture.h"

Texture::Texture(GLenum target)
{
    textureTarget = target;
    image = NULL;
}
Texture::~Texture()
{
}

bool Texture::LoadImage(const char* fileName)
{
    try
    {
        image = new Magick::Image(fileName);
        image->write(&blob, "RGBA");
    }
    catch(Magick::Error error)
    {
        Error (error.what());
        return false;
    }

    glGenTextures(1, &textureObject);
    glBindTexture(textureTarget, textureObject);
    glTexImage2D(textureTarget, 0, GL_RGBA, image->columns(), image->rows(), 0, GL_RGBA, GL_UNSIGNED_BYTE, blob.data());
    glTexParameterf(textureObject, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(textureObject, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    return true;
}

void Texture::Bind(GLenum textureUnit)
{
    glActiveTexture(textureUnit);
    glBindTexture(textureTarget, textureObject);
}

Thogl.h

#pragma once

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <fstream>
#include <string>
#include <glm.hpp>
#include <gtx/transform.hpp>
#include <map>
#include "Texture.h"


using namespace std;

class Thogl
{
public:
    Thogl();
    ~Thogl();

    bool init(int windowWidth, int windowHeight, const char* windowTitle);

    Texture* CreateTexture(const char* textureName, const char* fileName);
    Texture* CreateTexture(const char* textureName);

    void Start(void (*RunCallback)());

private:
    void run();
    GLFWwindow* window;
    static void KeyCallback(GLFWwindow*, int key, int scancode, int action, int mods);
    void SetCallbacks();
    void Terminate();
    map<string, Texture*> Textures;
    void (*RunCallback)(); 
};


void Error(const char* error);

Thogl.cpp

#include "Thogl.h"

ofstream errorLog;


Thogl::Thogl()
{
    Magick::Image* image;
    Magick::Blob blob;
    try
    {
        image = new Magick::Image("//Lol.png");
        image->write(&blob);
    }
    catch(Magick::Error error)
    {
        Error(error.what());
    }
}
Thogl::~Thogl()
{
}

void Thogl::run()
{
    while (!glfwWindowShouldClose(window))
    {
        RunCallback();


        glfwSwapBuffers(window);
        glfwPollEvents();
    }
}

bool Thogl::init(int screenWidth, int screenHeight, const char* windowTitle)
{
    errorLog.open("Error.log");

    if (!glfwInit())
    {
        Error("Could not initialize GLFW library");
        return false;
    }

    window = glfwCreateWindow(screenWidth, screenHeight, windowTitle, NULL, NULL);
    if (!window)
    {
        errorLog << "Error: Could not initialize GLFW window\n";
        glfwTerminate();
        return false;
    }
    glfwMakeContextCurrent(window);

    GLenum error = glewInit();
    if (error != GLEW_OK)
    {
        errorLog << "Error GLEW: " << glewGetErrorString(error) << "\n";
        return false;
    }

    SetCallbacks();

    glClearColor(138.f,43.f,226.f, 0);

    return true;
}

void Thogl::KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{

}

void Thogl::SetCallbacks()
{
    glfwSetKeyCallback(window, KeyCallback);
}

void Thogl::Terminate()
{
    glfwDestroyWindow(window);
    glfwTerminate();
    errorLog.close();
}

void Error(const char* error)
{
    errorLog << "Error: " << error << "\n";
}

void Thogl::Start(void (*Callback)())
{
    RunCallback = Callback;
    run();
}

Texture* Thogl::CreateTexture(const char* textureName, const char* fileName)
{
    Texture* newTexture = new Texture(GL_TEXTURE_2D);
    if (!newTexture->LoadImage(fileName))
    {
        Error("Couldn't load image file");
        return 0;
    }

    Textures.insert(make_pair(textureName, newTexture));

    return newTexture;
}

Texture* Thogl::CreateTexture(const char* textureName)
{
    Texture *newTexture = new Texture(GL_TEXTURE_2D);

    Textures.insert(make_pair(textureName, newTexture));

    return newTexture;
}

这是在VS2010 express上编译时的输出：

>------ Build started: Project: 2DEngine, Configuration: Debug Win32 ------
>  Thogl.cpp
>  Texture.cpp
> thogl.h(25): error C2143: syntax error : missing ';' before '*'
> thogl.h(25): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
> thogl.h(25): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
> thogl.h(25): warning C4183: 'CreateTexture': missing return type; assumed to be a member function     returning 'int'
> thogl.h(26): error C2143: syntax error : missing ';' before '*'
> thogl.h(26): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
> thogl.h(26): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
> thogl.h(26): warning C4183: 'CreateTexture': missing return type; assumed to be a member function returning 'int'
> thogl.h(36): error C2065: 'Texture' : undeclared identifier
> thogl.h(36): error C2059: syntax error : '>'
> thogl.h(38): error C2143: syntax error : missing ';' before '}'
> texture.h(8): error C2143: syntax error : missing ';' before '{'
> texture.h(24): error C2143: syntax error : missing ';' before '}'
> texture.cpp(4): error C2653: 'Texture' : is not a class or namespace name
> texture.cpp(5): error C2143: syntax error : missing ';' before '{'
> texture.cpp(8): error C2143: syntax error : missing ';' before '}'
> texture.cpp(9): error C2653: 'Texture' : is not a class or namespace name
> texture.cpp(9): fatal error C1903: unable to recover from previous error(s); stopping compilation
>  Generating Code...
>  Skipping... (no relevant changes detected)
>  Main.cpp
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

两个头文件之间存在循环依赖关系。它们包括在一起。但是编译器会跳过循环包含（你告诉它使用#pragma once）并且在首先解析的文件中，其他文件中的类型将是未知的，从而导致错误。

要解决此问题，您应该删除循环包含（Texture.h似乎不需要Thogl.h）或使用所需类型的前向声明。

C ++中无法解释的错误

1 个答案: