gl_test.cpp

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

//-----------------------------------------------------------------------------
//
static void error_callback( int error, const char* description )
{
    fputs( description, stderr );
}

//-----------------------------------------------------------------------------
//
static void key_callback( GLFWwindow* window, int key, int scancode, int action,
                          int mods)
{
    if( key == GLFW_KEY_ESCAPE && action == GLFW_PRESS )
    {
        glfwSetWindowShouldClose( window, GL_TRUE );
    }
}

    glfwWindowHint( GLFW_SAMPLES, 4 ); // 4x antialiasing

    //We don't want the old OpenGL
    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );

    glfwSetErrorCallback( error_callback );

    if( !glfwInit() )
    {
        exit( EXIT_FAILURE );
    }

    GLFWwindow* window = glfwCreateWindow( 640, 480, "Simple example", NULL, NULL );

    if( !window )
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glfwMakeContextCurrent( window );
    glfwSetKeyCallback( window, key_callback );

    while( !glfwWindowShouldClose(window) )
    {
        float ratio;
        int width, height;
        glfwGetFramebufferSize( window, &width, &height );
        ratio = width / (float) height;

        glViewport( 0, 0, width, height );
        glClear( GL_COLOR_BUFFER_BIT );
        glMatrixMode( GL_PROJECTION );
        glLoadIdentity();
        glOrtho( -ratio, ratio, -1.f, 1.f, 1.f, -1.f );
        glMatrixMode( GL_MODELVIEW );
        glLoadIdentity();
        glRotatef( (float) glfwGetTime() * 50.f, 0.f, 0.f, 1.f );

        //glBegin( GL_TRIANGLES );
        //glColor3f( 1.f, 0.f, 0.f );
        //glVertex3f( -0.6f, -0.4f, 0.f );
        //glColor3f( 0.f, 1.f, 0.f );
        //glVertex3f( 0.6f, -0.4f, 0.f );
        //glColor3f( 0.f, 0.f, 1.f );
        //glVertex3f( 0.f, 0.6f, 0.f );
        //glEnd();

        // this code will draw a point located at [100, 100, -25]
        glBegin(GL_POINTS);
        glVertex3f(0.0f, 0.0f, 0.0f);
        glEnd( );
        // next code will draw a line at starting and ending coordinates specified by glVertex3f
        glBegin(GL_LINES);
        glVertex3f(100.0f, 100.0f, 0.0f); // origin of the line
        glVertex3f(200.0f, 140.0f, 5.0f); // ending point of the line
        glEnd( );
        // the following code draws a triangle
        glBegin(GL_TRIANGLES);
        glVertex3f(100.0f, 100.0f, 0.0f);
        glVertex3f(150.0f, 100.0f, 0.0f);
        glVertex3f(125.0f, 50.0f, 0.0f);
        glEnd( );
        // this code will draw two lines "at a time" to save
        // the time it takes to call glBegin and glEnd.
        glBegin(GL_LINES);
        glVertex3f(100.0f, 100.0f, 0.0f); // origin of the FIRST line
        glVertex3f(200.0f, 140.0f, 5.0f); // ending point of the FIRST line
        glVertex3f(120.0f, 170.0f, 10.0f); // origin of the SECOND line
        glVertex3f(240.0f, 120.0f, 5.0f); // ending point of the SECOND line
        glEnd( );

        glfwSwapBuffers( window );
        glfwPollEvents();
    }

    glfwDestroyWindow( window );
    glfwTerminate();
    exit( EXIT_SUCCESS );