fractal.cpp

// File fractal.cpp
// Hugo Gallée
// Sat Feb 25 14:27:56 CET 2012

#include <GL/glut.h>
#include <math.h>
#include <stdio.h>

typedef struct point {
  float x;
  float y;
} Point;


void drawTriangle (Point a, Point b, Point c) {
  float z = 0.0;
  glBegin(GL_LINE_LOOP);
    glColor3f (0.0, 0.0, 1.0);
    glVertex3f(a.x, a.y, z);
    glVertex3f(b.x, b.y, z);
    glVertex3f(c.x, c.y, z);
  glEnd();
}

float distance (Point a, Point b) {
  return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

void drawFractal(Point a, Point b, float alpha, int prof) {
  float dist;
  if ((dist = distance(a, b)) < 0.01)return;

  Point c;
  float teta = 0.7;
  float r = dist / (2 * cos(teta));

  c.x = r * cos(teta + alpha) + a.x;
  c.y = r * sin(teta + alpha) + a.y;

  drawTriangle(a, b, c);
  drawFractal(a, c, alpha + teta, prof+1);
  drawFractal(c, b, alpha - teta, prof+1);
}

void init (void) {
    // select clearing color
    glClearColor (0.0, 0.0, 0.0, 0.0);

    // initialize viewing values
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}

void display(void) {
    // clear all pixels
    glClear (GL_COLOR_BUFFER_BIT);

    Point a, b;
    a.x = 0.2;
    a.y = 0.5;
    b.x = 0.8;
    b.y = 0.5;

    drawFractal(a, b, 0.0, 0);
    drawFractal(b, a, M_PI, 0);

    // Swap the buffers to show the oneon which we writed
    glutSwapBuffers();
}

/*
 * Declare initial window size, position, and display mode
 * (double buffer and RGB).  Open window with "hello"
 * in its title bar.  Call initialization routines.
 * Register callback function to display graphics.
 * Enter main loop and process events.
 */
int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize (500, 500);
    glutInitWindowPosition (100, 100);
    glutCreateWindow ("triangles");
    init ();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}