Spirograph

/*
 *  harmonograph.cpp
 *
 *  Created by Brecht Debackere on 02/04/10.
 *  Copyright 2010 Autofasurer. All rights reserved.
 *
 */
 
#include <GLUT/glut.h>
#include <iostream>
using namespace std;
 
//initialising variables
float fRed = 1.0, fGreen = 1.0, fBlue =1.0, fXpos = 0.0, fYpos = 0.0, fFrequency = 0.0, fAmplitude = 0.0, fPhase = 0.0, fTime = 0.0, fPointsize = 1.0;
 
 
//initialising states 
void init()
{
	glClearColor(0.0,0.0,0.0,0.7);
	glEnable(GL_BLEND);
	glBlendFunc(GL_ONE, GL_ONE);
}
 
//reshaping the viewport and projection
void reshape(int width, int height)
{
	glViewport(0, 0, 1440, 900);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.,(GLfloat) width/(GLfloat) height,0.1, 800.0);
	glMatrixMode(GL_MODELVIEW);
	gluLookAt(0.0,0.0,10.0, 0.0, 0.0, 0.0, 0,1,0);
 
}
 
//reading the keyboard input
void key(unsigned char key, int x, int y){
	switch (key){
		case 32:
			fFrequency = (rand()%500-250)/5.0;
			fPhase = (rand()%500-250)/5.0;
			fAmplitude = (rand()%500-250)/5.0; 
			fTime = 0.0;
			break;
	}
}
 
 
//drawing and displaying 
void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glBegin(GL_LINE_STRIP); 
	while (fTime < 400.0) {
		glColor3d(fRed, fGreen, fBlue);
		fXpos = 4*(cos(fFrequency * fTime) + cos(fPhase * fTime)*0.5 + cos(fAmplitude * fTime)*0.33);
		fYpos = 4*(sin(fFrequency * fTime) + sin(fPhase * fTime)*0.5 + sin(fAmplitude * fTime)*0.33);
		glVertex3f(fXpos, fYpos, 0);
		fTime += 0.002;	
	}
	glEnd();
	fFrequency -= 0.0001;	
	fAmplitude += 0.0001;	
	fPhase += 0.0001;
	fTime = 0.0;
	glutSwapBuffers();
	fRed = (rand()%100)/400.0;
	fGreen = (rand()%100)/400.0;
	fBlue = (rand()%100)/400.0;
}
 
//main loop with initialising of window and glut, assigning functions
int main(int argc, char** argv)
{
	srand(time(NULL));
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutGameModeString("1440x900:32");
	glutEnterGameMode();
	init();
	glutDisplayFunc(display);
	glutIdleFunc(display);
	glutReshapeFunc(reshape);
	glutKeyboardFunc(key);
	glutMainLoop();
	return 0;	
}