#include <GL/glut.h>


void RenderScene(void) {
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f, 0.0f, 0.0f);
    glRectf(-25.0f, 25.0f, 25.0f, -25.0f);

    glFlush();
}

void ColorSceneInit(void) {
    glClearColor(0.5f, 0.25f, 1.0f, 0.0f);
}

void ResizeWindow(GLsizei w, GLsizei h) {
    GLfloat ratio;

    if (h == 0) h = 1;

    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    ratio = (GLfloat) w / (GLfloat) h;
    if (w <= h) {
        glOrtho(-100.0, 100.0, -100/ratio, 100.0/ratio, 1.0, -1.0);
    } else {
        glOrtho(-100.0 * ratio, 100.0 * ratio, -100.0, 100.0, 1.0, -1.0);
    }
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void main(int argcp, char **argv) {
    glutInit(&argcp, argv);
    glutInitWindowSize(640, 480);
    glutInitWindowPosition(0, 0);

    glutCreateWindow("OpenGL Application");
    glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);

    glutDisplayFunc(RenderScene);
    glutReshapeFunc(ResizeWindow);
    ColorSceneInit();

    glutMainLoop();
}