调用 OpenGL 函数时程序崩溃
Program crash when calling OpenGL functions
我正在尝试设置一个游戏引擎项目。我的 visual studio 项目已设置，因此我有一个 'engine' 项目与我的 'game' 项目分开。然后将引擎项目编译为dll供游戏项目使用。我已经下载并设置了 glfw 和 glew 以开始使用 openGL。我的问题是，每当我使用我的第一个 openGL 函数时，程序就会崩溃。我知道这与 glewinit 有关，即使 glew 正在成功初始化（没有控制台错误）。在我的引擎项目中，我有一个 window class ，在 window 构建时，应该设置 glew：
Window.h
#pragma once
#include "GL\glew.h"
#include "GLFW\glfw3.h"
#if (_DEBUG)
#define LOG(x) printf(x)
#else
#define LOG(x)
#endif
namespace BlazeGraphics
{
class __declspec(dllexport) Window
{
public:
Window(short width, short height, const char* title);
~Window();
void Update();
void Clear() const;
bool Closed() const;
private:
int m_height;
int m_width;
const char* m_title;
GLFWwindow* m_window;
private:
Window(const Window& copy) {}
void operator=(const Window& copy) {}
};
}
Window.cpp（调用 glewinit() 的地方）
#include "Window.h"
#include <cstdio>
namespace BlazeGraphics
{
//Needed to define outside of the window class (not sure exactly why yet)
void WindowResize(GLFWwindow* window, int width, int height);
Window::Window(short width, short height, const char* title) :
m_width(width),
m_height(height),
m_title(title)
{
//InitializeWindow
{
if (!glfwInit())
{
LOG("Failed to initialize glfw!");
return;
};
m_window = glfwCreateWindow(m_width, m_height, m_title, NULL, NULL);
if (!m_window)
{
LOG("Failed to initialize glfw window!");
glfwTerminate();
return;
};
glfwMakeContextCurrent(m_window);
glfwSetWindowSizeCallback(m_window, WindowResize);
}
//IntializeGl
{
//This needs to be after two functions above (makecontextcurrent and setwindowresizecallback) or else glew will not initialize
**if (glewInit() != GLEW_OK)
{
LOG("Failed to initialize glew!");
}**
}
}
Window::~Window()
{
glfwTerminate();
}
void Window::Update()
{
glfwPollEvents();
glfwSwapBuffers(m_window);
}
void Window::Clear() const
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
//Returns a bool because glfwwindowShouldClose returns a nonzero number or zero
bool Window::Closed() const
{
//Made it equal to 1 to take away warning involving converting an int to bool
return glfwWindowShouldClose(m_window) == 1;
}
//Not part of window class so defined above
void WindowResize(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
}
这是我的 main.cpp 文件，可以在我的游戏项目中找到，我目前在全局函数中拥有我的 openGL 功能（暂时）：
main.cpp
#include <iostream>
#include <array>
#include <fstream>
#include "GL\glew.h"
#include "GLFW\glfw3.h"
#include "../Engine/Source/Graphics/Window.h"
void initializeGLBuffers()
{
GLfloat triangle[] =
{
+0.0f, +0.1f, -0.0f,
0.0f, 1.0f, 0.0f,
-0.1f, -0.1f, 0.0f, //1
0.0f, 1.0f, 0.0f,
+0.1f, -0.1f, 0.0f, //2
0.0f, 1.0f, 0.0f,
};
GLuint bufferID;
glGenBuffers(1, &bufferID);
glBindBuffer(GL_ARRAY_BUFFER, bufferID);
glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, (sizeof(GLfloat)) * 6, nullptr);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, (sizeof(GLfloat)) * 6, (char*)((sizeof(GLfloat)) * 3));
GLushort indices[] =
{
0,1,2
};
GLuint indexBufferID;
glGenBuffers(1, &indexBufferID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
};
void installShaders()
{
//Create Shader
GLuint vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
//Add source or text file to shader object
std::string temp = readShaderCode("VertexShaderCode.glsl");
const GLchar* adapter[1];
adapter[0] = temp.c_str();
glShaderSource(vertexShaderID, 1, adapter, 0);
temp = readShaderCode("FragmentShaderCode.glsl").c_str();
adapter[0] = temp.c_str();
glShaderSource(FragmentShaderID, 1, adapter, 0);
//Compile Shadaer
glCompileShader(vertexShaderID);
glCompileShader(FragmentShaderID);
if (!checkShaderStatus(vertexShaderID) || !checkShaderStatus(FragmentShaderID))
return;
//Create Program
GLuint programID = glCreateProgram();
glAttachShader(programID, vertexShaderID);
glAttachShader(programID, FragmentShaderID);
//Link Program
glLinkProgram(programID);
if (!checkProgramStatus(programID))
{
std::cout << "Failed to link program";
return;
}
//Use program
glUseProgram(programID);
}
int main()
{
BlazeGraphics::Window window(1280, 720, "MyGame");
initializeGLBuffers();
installShaders();
while (!window.Closed())
{
window.Clear();
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
window.Update();
};
return 0;
}
现在，如果我要将 glewinit() 代码移到我的 main.cpp 中：
int main()
{
BlazeGraphics::Window window(1280, 720, "MyGame");
if (glewInit() != GLEW_OK)
{
LOG("Failed to initialize glew!");
}
initializeGLBuffers();
installShaders();
while (!window.Closed())
{
window.Clear();
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
window.Update();
};
return 0;
}
然后我的程序编译正常。为什么尝试在 engine.dll 内初始化 glew 会导致程序崩溃？感谢您的帮助。
GLEW 通过为每个 OpenGL 函数定义一个函数指针作为 全局变量 来工作。我们以glBindBuffer为例：
#define GLEW_FUN_EXPORT GLEWAPI
typedef void (GLAPIENTRY * PFNGLBINDBUFFERPROC) (GLenum target, GLuint buffer);
GLEW_FUN_EXPORT PFNGLBINDBUFFERPROC __glewBindBuffer;
所以我们只有一个 __glewBindBuffer 函数指针，glewInit 会将其设置为您的 OpenGL 实现中的正确地址。
为了真正能够编写 glBindBuffer，GLEW 简单地定义了将 GL 函数映射到那些函数指针变量的预处理器宏：
#define glBindBuffer GLEW_GET_FUN(__glewBindBuffer);
Why does trying to initialize glew within engine.dll cause a program crash?
因为您的 engine.dll 和您的主应用程序各有一组单独的所有这些全局变量。您必须从引擎 DLL 中导出所有 __glew* 变量才能访问 engine.dll.
中 glewInit 调用的结果
我正在尝试设置一个游戏引擎项目。我的 visual studio 项目已设置，因此我有一个 'engine' 项目与我的 'game' 项目分开。然后将引擎项目编译为dll供游戏项目使用。我已经下载并设置了 glfw 和 glew 以开始使用 openGL。我的问题是，每当我使用我的第一个 openGL 函数时，程序就会崩溃。我知道这与 glewinit 有关，即使 glew 正在成功初始化（没有控制台错误）。在我的引擎项目中，我有一个 window class ，在 window 构建时，应该设置 glew：
Window.h
#pragma once
#include "GL\glew.h"
#include "GLFW\glfw3.h"
#if (_DEBUG)
#define LOG(x) printf(x)
#else
#define LOG(x)
#endif
namespace BlazeGraphics
{
class __declspec(dllexport) Window
{
public:
Window(short width, short height, const char* title);
~Window();
void Update();
void Clear() const;
bool Closed() const;
private:
int m_height;
int m_width;
const char* m_title;
GLFWwindow* m_window;
private:
Window(const Window& copy) {}
void operator=(const Window& copy) {}
};
}
Window.cpp（调用 glewinit() 的地方）
#include "Window.h"
#include <cstdio>
namespace BlazeGraphics
{
//Needed to define outside of the window class (not sure exactly why yet)
void WindowResize(GLFWwindow* window, int width, int height);
Window::Window(short width, short height, const char* title) :
m_width(width),
m_height(height),
m_title(title)
{
//InitializeWindow
{
if (!glfwInit())
{
LOG("Failed to initialize glfw!");
return;
};
m_window = glfwCreateWindow(m_width, m_height, m_title, NULL, NULL);
if (!m_window)
{
LOG("Failed to initialize glfw window!");
glfwTerminate();
return;
};
glfwMakeContextCurrent(m_window);
glfwSetWindowSizeCallback(m_window, WindowResize);
}
//IntializeGl
{
//This needs to be after two functions above (makecontextcurrent and setwindowresizecallback) or else glew will not initialize
**if (glewInit() != GLEW_OK)
{
LOG("Failed to initialize glew!");
}**
}
}
Window::~Window()
{
glfwTerminate();
}
void Window::Update()
{
glfwPollEvents();
glfwSwapBuffers(m_window);
}
void Window::Clear() const
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
//Returns a bool because glfwwindowShouldClose returns a nonzero number or zero
bool Window::Closed() const
{
//Made it equal to 1 to take away warning involving converting an int to bool
return glfwWindowShouldClose(m_window) == 1;
}
//Not part of window class so defined above
void WindowResize(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
}
这是我的 main.cpp 文件，可以在我的游戏项目中找到，我目前在全局函数中拥有我的 openGL 功能（暂时）：
main.cpp
#include <iostream>
#include <array>
#include <fstream>
#include "GL\glew.h"
#include "GLFW\glfw3.h"
#include "../Engine/Source/Graphics/Window.h"
void initializeGLBuffers()
{
GLfloat triangle[] =
{
+0.0f, +0.1f, -0.0f,
0.0f, 1.0f, 0.0f,
-0.1f, -0.1f, 0.0f, //1
0.0f, 1.0f, 0.0f,
+0.1f, -0.1f, 0.0f, //2
0.0f, 1.0f, 0.0f,
};
GLuint bufferID;
glGenBuffers(1, &bufferID);
glBindBuffer(GL_ARRAY_BUFFER, bufferID);
glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, (sizeof(GLfloat)) * 6, nullptr);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, (sizeof(GLfloat)) * 6, (char*)((sizeof(GLfloat)) * 3));
GLushort indices[] =
{
0,1,2
};
GLuint indexBufferID;
glGenBuffers(1, &indexBufferID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
};
void installShaders()
{
//Create Shader
GLuint vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
//Add source or text file to shader object
std::string temp = readShaderCode("VertexShaderCode.glsl");
const GLchar* adapter[1];
adapter[0] = temp.c_str();
glShaderSource(vertexShaderID, 1, adapter, 0);
temp = readShaderCode("FragmentShaderCode.glsl").c_str();
adapter[0] = temp.c_str();
glShaderSource(FragmentShaderID, 1, adapter, 0);
//Compile Shadaer
glCompileShader(vertexShaderID);
glCompileShader(FragmentShaderID);
if (!checkShaderStatus(vertexShaderID) || !checkShaderStatus(FragmentShaderID))
return;
//Create Program
GLuint programID = glCreateProgram();
glAttachShader(programID, vertexShaderID);
glAttachShader(programID, FragmentShaderID);
//Link Program
glLinkProgram(programID);
if (!checkProgramStatus(programID))
{
std::cout << "Failed to link program";
return;
}
//Use program
glUseProgram(programID);
}
int main()
{
BlazeGraphics::Window window(1280, 720, "MyGame");
initializeGLBuffers();
installShaders();
while (!window.Closed())
{
window.Clear();
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
window.Update();
};
return 0;
}
现在，如果我要将 glewinit() 代码移到我的 main.cpp 中：
int main()
{
BlazeGraphics::Window window(1280, 720, "MyGame");
if (glewInit() != GLEW_OK)
{
LOG("Failed to initialize glew!");
}
initializeGLBuffers();
installShaders();
while (!window.Closed())
{
window.Clear();
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);
window.Update();
};
return 0;
}
然后我的程序编译正常。为什么尝试在 engine.dll 内初始化 glew 会导致程序崩溃？感谢您的帮助。
GLEW 通过为每个 OpenGL 函数定义一个函数指针作为 全局变量 来工作。我们以glBindBuffer为例：
#define GLEW_FUN_EXPORT GLEWAPI
typedef void (GLAPIENTRY * PFNGLBINDBUFFERPROC) (GLenum target, GLuint buffer);
GLEW_FUN_EXPORT PFNGLBINDBUFFERPROC __glewBindBuffer;
所以我们只有一个 __glewBindBuffer 函数指针，glewInit 会将其设置为您的 OpenGL 实现中的正确地址。
为了真正能够编写 glBindBuffer，GLEW 简单地定义了将 GL 函数映射到那些函数指针变量的预处理器宏：
#define glBindBuffer GLEW_GET_FUN(__glewBindBuffer);
Why does trying to initialize glew within
engine.dllcause a program crash?
因为您的 engine.dll 和您的主应用程序各有一组单独的所有这些全局变量。您必须从引擎 DLL 中导出所有 __glew* 变量才能访问 engine.dll.
glewInit 调用的结果