[OpenGL Tutorial]1. 윈도우 열기

https://www.opengl-tutorial.org/beginners-tutorials/tutorial-1-opening-a-window/

Tutorial 1 : Opening a window

 

 

* 예제 코드 

// Include standard headers
#include <stdio.h>
#include <stdlib.h>

// Include GLEW
#include <GL/glew.h>

// Include GLFW : 창과 키보드를 처리
#include <GLFW/glfw3.h>
GLFWwindow* window;

// Include GLM : 3D 수학을 위한 라이브러리
#include <glm/glm.hpp>
using namespace glm; // glm::vec3말고, vec3을 입력할 수 있도록

int main( void )
{
	// Initialize GLFW (초기화)
    glewExperimental = true;
	if( !glfwInit() )
	{
		fprintf( stderr, "Failed to initialize GLFW\n" );
		getchar();
		return -1;
	}

	glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // We want OpenGL 3.3
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // To make macOS happy; should not be needed
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	// Open a window and create its OpenGL context
    GLFWwindow* window; // (In the accompanying source code, this variable is global for simplicity)
	window = glfwCreateWindow( 1024, 768, "Tutorial 01", NULL, NULL);
	if( window == NULL ){
		fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
		getchar();
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window); // Initialize GLEW

	// Initialize GLEW
    glewExperimental=true; // Needed in core profile
	if (glewInit() != GLEW_OK) {
		fprintf(stderr, "Failed to initialize GLEW\n");
		getchar();
		glfwTerminate();
		return -1;
	}

	// Ensure we can capture the escape key being pressed below
	glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

	// Dark blue background
	glClearColor(0.0f, 0.0f, 0.4f, 0.0f);

	do{
		// Clear the screen. It's not mentioned before Tutorial 02, but it can cause flickering, so it's there nonetheless.
		glClear( GL_COLOR_BUFFER_BIT );

		// Draw nothing, see you in tutorial 2 !

		
		// Swap buffers
		glfwSwapBuffers(window);
		glfwPollEvents();

	} // Check if the ESC key was pressed or the window was closed
	while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
		   glfwWindowShouldClose(window) == 0 );

	// Close OpenGL window and terminate GLFW
	glfwTerminate();

	return 0;
}

 

* 코드 설명 

- 콘솔에 메시지를 표시하기 위해 필요

#include <stdio.h>
#include <stdlib.h>

- GLFW가 창과 키보드를 처리 

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

- 3D 수학을 위한 라이브러리

- glm::vec3대신, vec3을 입력하기 위한 glm 네임스페이스 

#include <glm/glm.hpp>
using namespace glm;

 

 

- GLFW 초기화

glewExperimental = true; // Needed for core profile
if( !glfwInit() )
{
    fprintf( stderr, "Failed to initialize GLFW\n" );
    return -1;
}

 

 

- OpenGL 창 만들기 (윈도우 해상도 : 1024x768 , 윈도우 제목 : "Tutorial 01")

// 윈도우 힌트 설정 
glfwWindowHint(GLFW_SAMPLES, 4); // 4배 안티앨리어싱 설정
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // OpenGL 3.3 버전 사용 
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // MacOS 호환성을 위한 설정 (필수 x)
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 최신 OpenGL 사용

// 윈도우 생성, OpenGL 컨텍스트 설정  
GLFWwindow* window; // (In the accompanying source code, this variable is global for simplicity)
window = glfwCreateWindow( 1024, 768, "Tutorial 01", NULL, NULL); // 윈도우 생성
if( window == NULL ){
    fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
    glfwTerminate();
    return -1;
}
glfwMakeContextCurrent(window); // OpenGL 컨텍스트 설정
// GLEW 초기화 
glewExperimental=true; // 코어 프로파일에서 필요
if (glewInit() != GLEW_OK) {
    fprintf(stderr, "Failed to initialize GLEW\n");
    return -1;
}

 

- 창이 나타나고, 바로 닫히게 하기 + Escape키 누를 때까지 기다리기

// 입력 모드 설정 (ESC 키 입력을 감지할 수 있도록)
glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE); // sticky keys 모드를 활성화

do{
    // 화면 클리어 (화면 깜빡임 방지)
    glClear( GL_COLOR_BUFFER_BIT );

    // Draw nothing, see you in tutorial 2 !

    glfwSwapBuffers(window); // 버퍼 스왑 (프론트/ 백 버퍼 교체)
    glfwPollEvents(); // 이벤트 처리 (키보드, 마우스)

} // ESC 키가 눌리거나 윈도우가 닫힐 때까지 반복
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
       glfwWindowShouldClose(window) == 0 );

 

* 실행결과