Grafika példa program

#include <math.h>
#include <stdlib.h>

#if defined(__APPLE__)
  #include <OpenGL/gl.h>
  #include <OpenGL/glu.h>
  #include <GLUT/glut.h>
#else
  #if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
    #include <windows.h>
  #endif
  #include <GL/gl.h>
  #include <GL/glu.h>
  #include <GL/glut.h>
#endif

struct Vector {
  float x, y;
  Vector(float x = 0.0f, float y = 0.0f) : x(x), y(y) {}
};

Vector trans(0, 0), scale(1, 1);
float angle;

void onInitialization() {
  glMatrixMode(GL_PROJECTION);
  gluOrtho2D(-5, 5, -5, 5);
}

void onDisplay() {
  glClear(GL_COLOR_BUFFER_BIT);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  // Eltolás a megadott vektorral
  glTranslatef(trans.x, trans.y, 0);
  // Z tengely azaz (0, 0, 1) vektor körüli forgatás
  // A szöget fokban várja nem radiánban.
  glRotatef(angle, 0, 0, 1);
  // Skálázás (nagyítás), koordinátánként.
  glScalef(scale.x, scale.y, 1);

  glLineWidth(1);
  glBegin(GL_LINES); {
    // Négyzetrács
    for(int i = -100; i <= 100; i++) {
      glColor3f(1.0f, 1.0f, 1.0f);
      glVertex2f(i, -100);
      glVertex2f(i, +100);

      glVertex2f(-100, i);
      glVertex2f(+100, i);
    }
  } glEnd();

  glLineWidth(4);
  glBegin(GL_LINES); {
    // X tengely
    glColor3f(1.0f, 0.0f, 0.0f);
    glVertex2f(-5.0f, 0.0f);
    glVertex2f(5.0f, 0.0f);
    glVertex2f(4.5f, 0.5f);
    glVertex2f(5.0f, 0.0f);
    glVertex2f(4.5f, -0.5f);
    glVertex2f(5.0f, 0.0f);

    // Y tengely
    glColor3f(0.0f, 1.0f, 0.0f);
    glVertex2f(0.0f, -5.0f);
    glVertex2f(0.0f, 5.0f);
    glVertex2f(0.5f, 4.5f);
    glVertex2f(0.0f, 5.0f);
    glVertex2f(-0.5f, 4.5f);
    glVertex2f(0.0f, 5.0f);
  } glEnd();

  glutSwapBuffers();
}

void onIdle() {
  float time = glutGet(GLUT_ELAPSED_TIME) / 1000.0f;
  if(2.0f < time && time < 4.0f) {
    scale.x = (time-2)/2 + 1;
    scale.y = (time-2)/2 * 1.5 + 1;
  } else if(4.0f < time && time < 6.0f) {
    angle = (time-4)/2 * 67;
  } else if(6.0f < time && time < 8.0f) {
    trans.x = (time-6)/2 * 2.7;
    trans.y = (time-6)/2 * -3.1;
  }

  glutPostRedisplay();
}

void onMouse(int, int, int, int) {}

void onMouseMotion(int, int) {}

void onKeyboard(unsigned char, int, int) {}

void onKeyboardUp(unsigned char, int, int) {}

int main(int argc, char **argv) {
  glutInit(&argc, argv);
  glutInitWindowSize(600, 600);
  glutInitWindowPosition(100, 100);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);

  glutCreateWindow("Grafika pelda program");

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  onInitialization();

  glutDisplayFunc(onDisplay);
  glutMouseFunc(onMouse);
  glutIdleFunc(onIdle);
  glutKeyboardFunc(onKeyboard);
  glutKeyboardUpFunc(onKeyboardUp);
  glutMotionFunc(onMouseMotion);

  glutMainLoop();

  return 0;
}