# OpenGL The simplest OpenGL example

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Hi all,

I'm starting OpenGL using a tut on the Web. But at this point I would like to know the primitives needed for creating a window using OpenGL. So on Windows and using MS VS 2017, what is the simplest code required to render a window with the title of "First Rectangle", please?

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Check this if you don't mind using a little library to help you:

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Its a single header file library which creates a window and a legacy or modern opengl rendering context. You wont get it easier than this.

Edited by Finalspace

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Sorry but these are not what I need!

The window I'm talking about should presumably have only few lines of code.

We want a simple, say, 800x600, window with a title like "First Window". That's all.

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Wait, but if youre wanting to open a window using OpenGL .. the first link from @Abecederia seems to just that... so would be exactly what you need? what kind of code were you thinking you would need to open a window?

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Maybe this example will be usefull for you. I wrote a program that writes a point with glPointSize = 10.0 using VBO, VAO, FreeGLUT, OpengGL 3.3 Core, VS2015: DrawingPointUsingVBOAndVAO.zip

This is a program settings for VS2015:

Quote

Configuration: All Configurations; Platforms: All Platforms
C/C++ -> Genaral -> Additional Include Directories:
$(SolutionDir).\Libs\glm-0.9.8.4$(SolutionDir).\Libs\glew-2.0.0-win32\include
$(SolutionDir).\Libs\freeglut-MSVC-3.0.0-2.mp\freeglut\include Linker -> Input -> Additional Dependencies freeglut.lib glew32s.lib Configuration: All Configurations; Platforms: Win32 Linker -> General -> Additional Library Directories:$(SolutionDir).\Libs\glew-2.0.0-win32\lib\Platform_Win32
$(SolutionDir).\Libs\freeglut-MSVC-3.0.0-2.mp\freeglut\lib\Platform_Win32 Build Events -> Post-Build Event xcopy /y /d$(SolutionDir)Libs\freeglut-MSVC-3.0.0-2.mp\freeglut\freeglut_bin\Platform_Win32\freeglut.dll $(OutDir) Configuration: All Configurations; Platforms: x64 Linker -> General -> Additional Library Directories:$(SolutionDir).\Libs\glew-2.0.0-win32\lib\Platform_x64
$(SolutionDir).\Libs\freeglut-MSVC-3.0.0-2.mp\freeglut\lib\Platform_x64 Build Events -> Post-Build Event xcopy /y /d$(SolutionDir)Libs\freeglut-MSVC-3.0.0-2.mp\freeglut\freeglut_bin\Platform_x64\freeglut.dll \$(OutDir)

#define GLEW_STATIC

#include <GL/glew.h>
#include <GL/freeglut.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <string>
#include <iostream>
using namespace std;

extern "C" _declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;

"#version 330\n \
\
in vec2 a_Position; \
\
void main()\
{ \
gl_Position = vec4(a_Position, 0.0, 1.0); \
gl_PointSize = 10.0; \
}";

"#version 330\n \
\
precision mediump float; \
out vec4 fragColor; \
\
void main()\
{ \
fragColor = vec4(1.0, 0.0, 0.0, 1.0); \
}";

{
GLint status;
if (status == GL_FALSE)
{
GLint infoLogLength;
GLchar *infoLog = new GLchar[infoLogLength];
cerr << "Compile log: " << infoLog << endl;
delete[] infoLog;
}
}
GLuint vao;
void Display()
{
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(vao);
glDrawArrays(GL_POINTS, 0, 1);
glutSwapBuffers();
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitContextVersion(3, 3);
glutInitContextFlags(GLUT_CORE_PROFILE | GLUT_DEBUG);
glutInitWindowSize(500, 500);

string title = "Drawing Point Using VBO";
glutCreateWindow(title.c_str());
cout << title << endl;

glewInit();

GLuint program = glCreateProgram();
glUseProgram(program);
GLint status;
if (status == GL_FALSE)
{
GLint infoLogLength;

glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLength);
GLchar *infoLog = new GLchar[infoLogLength];
glGetProgramInfoLog(program, infoLogLength, NULL, infoLog);
cerr << "Link log: " << infoLog << endl;
delete[] infoLog;
}

GLfloat vertices[] = { 0.0f, 0.0f };

GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, 2 * sizeof(GLfloat), vertices, GL_STATIC_DRAW);

glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vbo);

GLint a_Position = glGetAttribLocation(program, "a_Position");
glVertexAttribPointer(a_Position, 2, GL_FLOAT, GL_FALSE, 0, NULL);
glEnableVertexAttribArray(a_Position);

glEnable(GL_PROGRAM_POINT_SIZE);

glutDisplayFunc(Display);

glutMainLoop();
return 0;
}

Edited by 8Observer8

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