인프런 커뮤니티 질문&답변

선생님 2019년도 맥북 프로 입니다.
OpenGL은 vcpkg로 설치를 진행을 했습니다.

=> 버전은 2022년12월4일에 배포된 버전인 3을 사용하고 있습니다.

현재 동작이 되는 코드는 다음과 같이 했을 때 동작을 하는 것을 확인 했습니다.

code

#include <iostream>

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

#include <glm/glm.hpp>

/** vertex shader source */
const char *vertexShaderSource = "#version 330 core \n"
                                 "in vec4 vertexPos; \n"
                                 "void main() { \n"
                                 "gl_Position = vertexPos; \n"
                                 "} \0";

/** fragment shader source */
const char *fragmentShaderSource = "#version 330 core \n"
                                   "out vec4 FragColor; \n"
                                   "void main(){ \n"
                                   "FragColor = vec4(1.0f, 0.0f, 0.0f, 1.0f); \n"
                                   "} \0";

/** vertex point coordinate */
GLfloat vertexPos[] = {
        -0.5F, -0.5F, 0.0F, 1.0F,
        +0.5F, -0.5F, 0.0F, 1.0F,
        -0.5F, +0.5F, 0.0F, 1.0F
};


/** event handler */
/** refresh handler */
void refreshHandler(GLFWwindow *window);

/** keyboard event handler */
void keyboardHandler(GLFWwindow *window, int key, int scancode, int action, int mods);

/** vertex program Initialized */
void initFunc(void);

/** draw shader source */
void drawFunc(void);

/** window size const set */
const unsigned int WIDTH = 800, HEIGHT = 600;

const unsigned int WIN_X = 100; // window position in pixels, (X, Y)
const unsigned int WIN_Y = 100;

GLuint VB0, VAO;


/** shader program ID */
GLuint shaderProgram;
/** vertex shader program ID */
GLuint vertexShader;
/** fragment shader program ID */
GLuint fragmentShader;


int main(int argc, char **argv) {

    /** GLFW Window variable */
    GLFWwindow *window = nullptr;

    /** glfw Initialized */
    if (glfwInit() == GLFW_FALSE) {
        std::cout << "GLFW Initialized Failed..." << std::endl;
        return -1;
    }

    /** OpenGL Version Hit -> glfw */
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);

    /** create window */
    window = glfwCreateWindow(WIDTH, HEIGHT, "Hello Vertex", NULL, NULL);
    /** window position setting (x, y)*/
    glfwSetWindowPos(window, WIN_X, WIN_Y);

    /** create window check */
    if (window == nullptr) {
        std::cout << "Create window failed ..." << std::endl;
        glfwTerminate();
        return -1;
    }

    /** glfw create window context */
    glfwMakeContextCurrent(window);

    glewExperimental = GL_TRUE;

    /** glew Initialized */
    if (glewInit() != GLEW_OK) {
        std::cout << "OpenGL extension GLEW Initialized Failed..." << std::endl;
        glfwTerminate();
        return -1;
    }

    /** glfw Event Handler Setting */
    /** keyboard event handler registration */
    glfwSetKeyCallback(window, keyboardHandler);
    /** refresh event handler registration */
    glfwSetWindowRefreshCallback(window, refreshHandler);

    /** back ground color setting -> RGBA */
    glClearColor(0.5F, 0.5F, 0.5F, 1.0F);
    /** vertex array create and get vertex array ID */
    glGenVertexArrays(1, &VAO);
    /** create buffer and get buffer ID */
    glGenBuffers(1, &VB0);

    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VB0);
    /** shader Initialized */
    initFunc();

    /** window loop */
    while (!glfwWindowShouldClose(window)) {
        /** event Listener */
        glfwPollEvents();
        /** frame buffer setting */
//        glClear(GL_COLOR_BUFFER_BIT);
        /** draw triangle */
        drawFunc();
        /** window frame buffer swap */
        glfwSwapBuffers(window);
    }
    /** using buffer remove */
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VB0);
    /** shader .obj file delete */
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    /** delete shader program */
    glDeleteProgram(shaderProgram);
    /** glfw terminate */
    glfwTerminate();
    return 0;
}

/** refresh handler */
void refreshHandler(GLFWwindow *window) {
    /** draw image */
    drawFunc();
    /** swap fraem buffer */
    glfwSwapBuffers(window);
}

/** keyboard event handler */
void keyboardHandler(GLFWwindow *window, int key, int scancode, int action, int mods) {
    switch (key) {
        case GLFW_KEY_ESCAPE:
            if (action == GLFW_PRESS) {
                glfwSetWindowShouldClose(window, GLFW_TRUE);
            }
            break;
    }
}


/** vertex program Initialized -> create shader and shader program */
void initFunc(void) {
    /** check log variable */
    int status;
    char log[1024] = {0,};
    /** vertex shader create */
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    /** vertex shader source set shader source */
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    /** vertex shader source code compile -> compile to get .OBJ */
    glCompileShader(vertexShader);
    /** check shader compile error */
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);
    std::cout << "vertex compile status : " << status << std::endl;
    if (!status) {
        glGetShaderInfoLog(vertexShader, 1024, NULL, log);
        std::cout << "vertex shader compile error - " << log << std::endl;
    }

    /** fragment shader create */
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    /** fragment shader source set shader source */
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    /** fragment shader source code compile -> compile to get .OBJ */
    glCompileShader(fragmentShader);
    /** check shader compile error */
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &status);
    std::cout << "fragment compile status : " << status << std::endl;
    if (!status) {
        glGetShaderInfoLog(fragmentShader, 1024, NULL, log);
        std::cout << "vertex shader compile error - " << log << std::endl;
    }

    /** shader program create */
    shaderProgram = glCreateProgram();
    /** vertex shader and fragment shader attach */
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    /** link program -> link to get .EXE */
    glLinkProgram(shaderProgram);

    /** program link check */
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &status);
    std::cout << "link status " << status << std::endl;
    if (!status) {
        glGetProgramInfoLog(shaderProgram, 1024, NULL, log);
        std::cout << "shader program linked failed -> " << log << std::endl;
    }

    /** shader program validated */
    glValidateProgram(shaderProgram);
    /** program link check */
    glGetProgramiv(shaderProgram, GL_VALIDATE_STATUS, &status);
    std::cout << "link status " << status << std::endl;
    if (!status) {
        glGetProgramInfoLog(shaderProgram, 1024, NULL, log);
        std::cout << "shader program linked failed -> " << log << std::endl;
    }

    /** using shader program */
    glUseProgram(shaderProgram);

}

/** draw shader source */
void drawFunc(void) {
    /** OpenGL FrameBuffer Clear */
    /** COLOR Buffer clear */
    glClear(GL_COLOR_BUFFER_BIT);


//    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPos), vertexPos, GL_DYNAMIC_DRAW);

    /** get attribute variable get -> input setting */
    GLint locationAttribute = glGetAttribLocation(shaderProgram, "vertexPos");
    /** setting shader source variable */
    glEnableVertexAttribArray(locationAttribute);
    /** get vertex source variable get */
    glVertexAttribPointer(locationAttribute, 4, GL_FLOAT, GL_FALSE, 0, vertexPos);

    /** draw a triangle */
    glDrawArrays(GL_TRIANGLES, 0, 3);

    /** frame buffer change and wait all shader program done */
    glFinish();

}

cmake

cmake_minimum_required(VERSION 3.27)

project(chapter0201HelloShaderProgram LANGUAGES CXX VERSION 0.0.1)

message("chapter02-01 hello shader program GLSL")

find_package(OpenGL REQUIRED)
find_package(glfw3 REQUIRED CONFIG)
find_package(GLEW REQUIRED CONFIG)
find_package(glm REQUIRED CONFIG)


add_executable(chapter0201HelloShaderProgram)

target_sources(chapter0201HelloShaderProgram PRIVATE
        main.cpp)

target_link_libraries(chapter0201HelloShaderProgram LINK_PRIVATE
        OpenGL::GL
        glfw
        GLEW::GLEW
        glm::glm

)

혹시 여기서 glGenVertexArray, glGenBuffer 가 무엇인지 알 수 있을까요?

관련된 자료를 찾다가 코드들이 항상 사용을 하길래 추가를 했더니 동작을 하는 것을 봐서 vertexarray에 대한 생성 및 c코드에서 넘겨 받는 값을 임시 저장을 하는데 사용이 되는 것 같은데 정확히 어떤 역할인지 궁금해서 문의 드립니다.

Mac 일 줄은 몰랐습니다.

Mac 쪽은 2018년 이후인가, 그 이후부터는 OpenGL 관련된 기능들을 deprecate 시켜서, 더 이상 지원하지 않습니다. 경우에 따라서는 오동작하는 상황이 나올 수 있을 겁니다.

glGenBuffers 등의 함수는 이 강의에서 설명하고 있습니다만, 조금 더 진행해야 설명이 나올 겁니다.

감사합니다.

네 감사합니다

윈도우 환경에서 확인을 해보도록 하겠습니다.