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c++ - 使用核心 OpenGL 版本

问题描述

我在 glsl 中编写着色器时遇到了我需要的功能在我使用的版本中不可用的问题。我跑了glxinfo | grep 'OpenGL'，得到了这个输出：

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Sandybridge Mobile 
OpenGL core profile version string: 3.3 (Core Profile) Mesa 18.3.6
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 18.3.6
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 18.3.6
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

根据输出，我可以访问 OpenGL core 3.3 和 GLSL core 3.30，如下所示：

OpenGL core profile version string: 3.3 (Core Profile) Mesa 18.3.6
OpenGL core profile shading language version string: 3.30

唯一的问题是，每当我尝试使用 GLSL 核心 330 时，都会收到一条错误消息： GLSL 3.30 is not supported. Supported versions are: 1.10, 1.20, 1.30, 1.00 ES, and 3.00 ES.

我正在使用 GLFW 创建一个 OpenGL 上下文。创建上下文的行是：glfwMakeContextCurrent(window);

有谁知道允许我访问 OpenGL 核心或以某种方式更新驱动程序以让我访问更高版本的 OpenGL 的方法？

____________________________________________________________________________

额外的信息：

格式：Code : output

glGetString(GL_VERSION) : 3.0 Mesa 18.3.6
glGetString (GL_SHADING_LANGUAGE_VERSION) : 1.30

着色器：

    vertex shader:
    #version 330 core
    
    layout(location = 0) in vec4 position;
    
    void main(){
       gl_Position = position;
    };
    


    fragment shader:
    #version 330 core
    
    layout(location = 0) out vec4 color;
    
    void main(){
       color = vec4(1.0, 0.0, 0.0, 1.0);
    };

这是我试图运行的代码：

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>

static unsigned int CompileShader(unsigned int type, const std::string& source){
    unsigned int id =  glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);
    
    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);
    if(result == GL_FALSE){
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        char* message = (char*)alloca(length * sizeof(char));
        glGetShaderInfoLog(id, length, &length, message);
        std::cout << "Failed to compile " << (type == GL_VERTEX_SHADER ? "vertex" : "fragment") << " shader!" << std::endl;
        std::cout << message << std::endl;
        glDeleteShader(id);
        return 0;
    }
    
    return id;
}

static unsigned int CreateShader(const std::string& vertexshader, const std::string& fragmentshader){
    unsigned int program = glCreateProgram();
    unsigned int vs = CompileShader(GL_VERTEX_SHADER,vertexshader);
    unsigned int fs = CompileShader(GL_FRAGMENT_SHADER,fragmentshader);
    
    glAttachShader(program, vs);
    glAttachShader(program, fs);
    glLinkProgram(program);
    glValidateProgram(program);
    
    glDeleteShader(vs);
    glDeleteShader(fs);
    return program;
}

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;
        
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context  current */
    glfwMakeContextCurrent(window);
    
    if(glewInit() != GLEW_OK){
        std::cout << "REEEEEEEEEEE" << std::endl;
    }
    
    std::cout << glGetString(GL_VERSION) << std::endl;
    std::cout << glGetString (GL_SHADING_LANGUAGE_VERSION) << std::endl;

    
    float vertices[6] = {
        -0.5f, -0.5f,
         0.0f,  0.5f,
        -0.5f, -0.5f
    };
    
    unsigned int buf;
    glGenBuffers(1, &buf);
    glBindBuffer(GL_ARRAY_BUFFER, buf);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), vertices, GL_STATIC_DRAW);
    
    glEnableVertexAttribArray(buf); // try replacing buf with 0
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
    
    std::string vertexshader = 
    "#version 330 core\n"
    "\n"
    "layout(location = 0) in vec4 position;\n"
    "\n"
    "void main(){\n"
    "   gl_Position = position;\n"
    "}\n";
    
    std::string fragmentshader = 
    "#version 330 core\n"
    "\n"
    "out vec4 color;\n"
    "\n"
    "void main(){\n"
    "   color = vec4(1.0, 0.0, 0.0, 1.0);\n"
    "}\n";
    
    unsigned int shader = CreateShader(vertexshader, fragmentshader);
    glUseProgram(shader);
    
    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT);
        
        glDrawArrays(GL_TRIANGLES, 0, 3);

        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}

操作系统： Linux Debian

标签： c++openglglslshaderrendering

解决方案

通过添加

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

在创建窗口之前，我能够让它工作。如果您不知道 MAJOR 和 MINOR 是什么意思，请看这里：What does major and minor mean in OpenGL with GLFW?

TLDR：“主要”和“次要”是单个版本号的两个组成部分，用点分隔。

因此，将主要版本和次要版本都设置为三个，我能够请求 OpenGL 3.3 Core Profile。

现在当我运行时：

std::cout << glGetString(GL_VERSION) << std::endl;
std::cout << glGetString (GL_SHADING_LANGUAGE_VERSION) << std::endl;

我得到：

3.3 (Core Profile) Mesa 18.3.6
3.30

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