glewInit（）失败和OpenGL错误1282

Question

我有一个非常基本的OpenGL程序，使用glfw3进行窗口操作。

这里是我的主要：

//Headers
#include <GL\glew.h>
#include <GLFW/glfw3.h>
#include "Utils.h"



//Function Prototypes
void setupEvents(GLFWwindow* window);


//Main function
int main(void)
{
    GLFWwindow* window;
    if (!glfwInit())    exit(EXIT_FAILURE);

    window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
    glewExperimental = GL_FALSE;
    GLenum error = glGetError();

    if (error != GL_NO_ERROR)
    {
        std::cout << "OpenGL Error: " << error << std::endl;
    }
    GLenum glewinit = glewInit();
    if (glewinit != GLEW_OK) {
        std::cout << "Glew not okay! " << glewinit;
        exit(EXIT_FAILURE);
    }
    if (!window){   glfwTerminate();    exit(EXIT_FAILURE); } //Failed to create window

    //Make our window current
    glfwMakeContextCurrent(window);
    setupEvents(window);

    //Let's make our program
    //GLuint glProgram = LoadShaders("../Shaders/Section_1/Basic.vert", "../Shaders/Section_1/Basic.frag");
    GLuint glProgram = LoadShaders("Basic.vert", "Basic.frag");

    while (!glfwWindowShouldClose(window))
    {
        glClear(GL_COLOR_BUFFER_BIT);

        //Swap buffers and call events.
        glfwSwapBuffers(window);
        glfwPollEvents();
    }



    //Destory our window and exit glfw.
    glfwDestroyWindow(window); 
    glfwTerminate();
    exit(EXIT_SUCCESS);
}

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    //The key callback
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}

void setupEvents(GLFWwindow* window) {
    //Setup our events.
    glfwSetKeyCallback(window, key_callback);
} 

Utils：

#include <GL\glew.h>
#include <glm/glm.hpp>
#include <fstream> 
#include <vector>
#include <stdlib.h>
#include <algorithm>
#include <iostream>
#include <string>

using namespace std;
GLuint LoadShaders(const char * vertex_file_path, const char * fragment_file_path){

    // Create the shaders
    GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
    GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);

    // Read the Vertex Shader code from the file
    std::string VertexShaderCode;
    std::ifstream VertexShaderStream(vertex_file_path, std::ios::in);
    if (VertexShaderStream.is_open())
    {
        std::string Line = "";
        while (getline(VertexShaderStream, Line))
            VertexShaderCode += "\n" + Line;
        VertexShaderStream.close();
    }

    // Read the Fragment Shader code from the file
    std::string FragmentShaderCode;
    std::ifstream FragmentShaderStream(fragment_file_path, std::ios::in);
    if (FragmentShaderStream.is_open()){
        std::string Line = "";
        while (getline(FragmentShaderStream, Line))
            FragmentShaderCode += "\n" + Line;
        FragmentShaderStream.close();
    }

    GLint Result = GL_FALSE;
    int InfoLogLength;

    // Compile Vertex Shader
    printf("Compiling shader : %s\n", vertex_file_path);
    char const * VertexSourcePointer = VertexShaderCode.c_str();
    glShaderSource(VertexShaderID, 1, &VertexSourcePointer, NULL);
    glCompileShader(VertexShaderID);

    // Check Vertex Shader
    glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
    glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
    std::vector<char> VertexShaderErrorMessage(InfoLogLength);
    glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
    fprintf(stdout, "%s\n", &VertexShaderErrorMessage[0]);

    // Compile Fragment Shader
    printf("Compiling shader : %s\n", fragment_file_path);
    char const * FragmentSourcePointer = FragmentShaderCode.c_str();
    glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer, NULL);
    glCompileShader(FragmentShaderID);

    // Check Fragment Shader
    glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
    glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
    std::vector<char> FragmentShaderErrorMessage(InfoLogLength);
    glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
    fprintf(stdout, "%s\n", &FragmentShaderErrorMessage[0]);

    // Link the program
    fprintf(stdout, "Linking program\n");
    GLuint ProgramID = glCreateProgram();
    glAttachShader(ProgramID, VertexShaderID);
    glAttachShader(ProgramID, FragmentShaderID);
    glLinkProgram(ProgramID);

    // Check the program
    glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
    glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
    std::vector<char> ProgramErrorMessage(max(InfoLogLength, int(1)));
    glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
    fprintf(stdout, "%s\n", &ProgramErrorMessage[0]);

    glDeleteShader(VertexShaderID);
    glDeleteShader(FragmentShaderID);

    return ProgramID;
}

输出：

OpenGL Error: 1282
Glew not okay! 1

我真的不知道我做错了什么。

Answer 1

您检查窗口创建失败的时间太晚了，您试图在没有活动GL上下文的情况下调用GL函数。两者都错了。它应该是（复制粘贴并重新排序代码）：

GLFWwindow* window;
if (!glfwInit())    exit(EXIT_FAILURE);

window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
if (!window){   glfwTerminate();    exit(EXIT_FAILURE); } //Failed to create window

//Make our window current
glfwMakeContextCurrent(window);

glewExperimental = GL_FALSE;
GLenum error = glGetError();

if (error != GL_NO_ERROR)
{
    std::cout << "OpenGL Error: " << error << std::endl;
}
GLenum glewinit = glewInit();
if (glewinit != GLEW_OK) {
    std::cout << "Glew not okay! " << glewinit;
    exit(EXIT_FAILURE);
}