GLEW不在MSYS2上定位OpenGL函数 [英] GLEW not locating OpenGL functions on MSYS2
问题描述
我正在尝试在笔记本电脑上使用OpenGL.作为最快的方法，我安装了MSYS2.我安装了 mingw-w64-x86_64-gcc ， mingw-w64-x86_64-glew ， mingw-w64-x86_64-glfw3 等.我认为我安装了所有必需的软件包.我调用OpenGL例程后，我的程序就给我分段错误.
I am trying to play with couple of OpenGL on my laptop. As the fastest method, I installed an MSYS2. I installed mingw-w64-x86_64-gcc, mingw-w64-x86_64-glew, mingw-w64-x86_64-glfw3 etc. I think I installed all the required packages. My programs are giving me segmentation fault as soon as I call an OpenGL routine.
作为一个最小的工作示例，我从 LearnOpenGL.com <复制了 Hello，Triangle 示例/a>，以使事情变小.我在这个程序中也遇到了同样的问题.
To make a minimal working example, I am copying the Hello, Triangle example from LearnOpenGL.com so that things will be kept small. I get the same problem in this program as well.
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
void processInput(GLFWwindow *window);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
const char *vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"void main()\n"
"{\n"
" gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\0";
const char *fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
" FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\n\0";
int main()
{
// glfw: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
#endif
// glfw window creation
// --------------------
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
std::cout << "setting opengl...\n" << std::flush;
int vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
// check for shader compile errors
int success;
char infoLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}
// fragment shader
int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
// check for shader compile errors
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
}
// link shaders
int shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
// check for linking errors
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
if (!success) {
glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
}
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
float vertices[] = {
-0.5f, -0.5f, 0.0f, // left
0.5f, -0.5f, 0.0f, // right
0.0f, 0.5f, 0.0f // top
};
unsigned int VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
while (!glfwWindowShouldClose(window))
{
processInput(window);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// draw our first triangle
glUseProgram(shaderProgram);
glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
glDrawArrays(GL_TRIANGLES, 0, 3);
// glBindVertexArray(0); // no need to unbind it every time
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glfwTerminate();
return 0;
}
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
我刚刚添加了打印声明
std::cout << "setting opengl...\n" << std::flush;
现在我可以看到此打印了.但是，如果我尝试在下面的任何一行上打印相同的内容，则看不到该打印内容，因为OpenGL调用给我造成了段错误.我只能进行的OpenGL调用是 glGetString ，并且可以在OpenGL 3.3中打印该版本.
and I can see this print now. But if I try to print the same thing on any of the line below that, I can't see the print since OpenGL calls give me seg fault. Only OpenGL call I can make is glGetString and I can print that my version in OpenGL 3.3.
作为旁注，我将其放在 main.cpp 中并编译为
As a side note, I am putting this in main.cpp and compile as
g++ main.cpp -o main -lglfw3 -lglew32 -lglu32 -lopengl32
可以正常播放，没有任何问题.
which compies without any problems.
推荐答案
必须使用 GLEW 库在OpenGL上下文已由 glfwMakeContextCurrent 变为当前值之后，由 glewInit 初始化.请参见初始化GLEW .
The GLEW library has to be initialized, by glewInit, after the OpenGL context has become current by glfwMakeContextCurrent. See Initializing GLEW.
添加以下代码，以解决您的问题:
Add the following code, to solve your issue:
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE;
if (glewInit() != GLEW_OK)
{
// error handling
}
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