在 OpenGL 中在 Mac 上编译着色器时出现“版本不支持”错误

Question

I have recently taken up an online tutorial on OpenGL (TheChernoProject) and everything went pretty good until I actually started writing shaders. when I compile my code, it runs, but nothing is displayed on screen, although there should be a red triangle.

I am writing this code on MacOS 10.14.6 in a terminal. I've downloaded both glfw and glew, and am compiling code using a following command:

clang++  -framework Cocoa -framework OpenGL -framework IOKit -framework CoreVideo -lglfw -lglew main.cpp -o main.o

I've already tried replacing #version 330 core with #version 440 core, since its the latest my Mac supports, but to no avail.

here is my code:

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

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){
        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;

    if(!glfwInit())return -1;
    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
        glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
        glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE );
        glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );

    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window){
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    if(glewInit() != GLEW_OK)return -1;

    float positions[6] = {
        -0.5f,-0.5f,
         0.0f, 0.5f,
         0.5f,-0.5f
    };

    unsigned int buffer;
    glGenBuffers(1,&buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), positions, GL_STATIC_DRAW);

    glEnableVertexAttribArray(0);   
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), 0);

    std::string fragmentShader =
        "#version 330 core\n"
        "layout(location = 0) out vec4 color;\n"
        "void main(){\n"
        "   color = vec4(1.0, 0.0, 0.0, 1.0);\n"
        "}\n";

    std::string vertexShader =
        "#version 330 core\n"
        "layout(location = 0) in vec4 position;\n"
        "void main(){\n"
        "   gl_Position = position;\n"
        "}\n";

    unsigned int shader = CreateShader(vertexShader, fragmentShader);
    glUseProgram(shader);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    while (!glfwWindowShouldClose(window)){

        glClear(GL_COLOR_BUFFER_BIT);

        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);

        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}

Answer 1

Ripi2 has it, you need a vertex array object (VAO) bound to render anything in a Core context:

# Mesa on Linux is about as picky as Apple's OpenGL implementation :)
$ g++ `pkg-config --cflags --libs glfw3 glew` main.cpp
$ MESA_DEBUG=1 ./a.out 
Mesa: User error: GL_INVALID_OPERATION in glVertexAttribPointer(no array object bound)
Mesa: User error: GL_INVALID_OPERATION in glDrawArrays(no VAO bound)

For example:

GLuint vao = 0;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
// glVertexAttribPointer()/glEnableVertexAttribArray()/glDraw*() calls here

All together:

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

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){
        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;

    if(!glfwInit())return -1;
    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
    glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
    glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE );
    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );

    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window){
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    if(glewInit() != GLEW_OK)return -1;

    float positions[6] = {
        -0.5f,-0.5f,
        0.0f, 0.5f,
        0.5f,-0.5f
    };

    GLuint vao = 0;
    glGenVertexArrays( 1, &vao );
    glBindVertexArray( vao );

    unsigned int buffer;
    glGenBuffers(1,&buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), positions, GL_STATIC_DRAW);

    glEnableVertexAttribArray(0);   
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), 0);

    std::string fragmentShader =
        "#version 330 core\n"
        "layout(location = 0) out vec4 color;\n"
        "void main(){\n"
        "   color = vec4(1.0, 0.0, 0.0, 1.0);\n"
        "}\n";

    std::string vertexShader =
        "#version 330 core\n"
        "layout(location = 0) in vec4 position;\n"
        "void main(){\n"
        "   gl_Position = position;\n"
        "}\n";

    unsigned int shader = CreateShader(vertexShader, fragmentShader);
    glUseProgram(shader);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    while (!glfwWindowShouldClose(window)){

        glClear(GL_COLOR_BUFFER_BIT);

        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);

        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}