// Demo for ECE660, 9/21/98, F.S.Hill,Jr.
// bare bones Canvas class..
/* Draw a rotating rosette of numSides sides. Increase/decrease numSides with 'n"/'N',
and increase/decrease rotation speed with 'r'/'R' */
#include <windows.h>
#include <iostream.h>
#include <math.h>
#include <gl/Gl.h>
#include <gl/Glu.h>
#include <gl/glut.h>
typedef struct { float x, y;} tRealPoint;
//<<<<<<<<<<<<<<<<<<<<<<<<<<< Canvas class definition >>>>>>>>>>>
class Canvas {
  private:
	tRealPoint CP; 	// current position in world
  public:
	Canvas(){CP.x = CP.y = 0.0;};// constructor 
	void lineTo(float x, float y);
	void moveTo(float x, float y){	CP.x = x; CP.y = y;}
};
//<<<<<<<<<<<<<<<<<<<<<<< lineTo >>>>>>>>>>>>>>>>>>>>>>>
void Canvas:: lineTo(float x, float y)
{
	glBegin(GL_LINES);
		glVertex2f((GLfloat)CP.x, (GLfloat)CP.y);
		CP.x = x; CP.y = y;
		glVertex2f((GLfloat)CP.x, (GLfloat)CP.y);
	glEnd();
	glFlush();
}
//######################## GLOBALS #################################
int screenWidth = 480, screenHeight = 480;
Canvas cvs; // create a global instance
int numSides = 11;
float angle = 0.0, delAngle = 0;
//<<<<<<<<<<<<<<<<<<<<<<< Rosette >>>>>>>>>>>>>>>>>>>>
void Rosette(int N, float radius)
{
	#define MaxNum 97         // can draw up to 97 vertex rosette
	tRealPoint pt[MaxNum];    // vertices of the N-gon
	float angle = 2 * 3.14159265 / N;

	if(N < 3 || N >= MaxNum) return;
	for (int j = 0; j < N; j++) // create the vertices  
	{
		pt[j].x =  radius * cos(angle * j); 
		pt[j].y =  radius * sin(angle * j);
	} 
	for(int i = 0; i < N -1;i++)
		for(int j = i+1; j < N ; j++)		
		{
			cvs.moveTo(pt[i].x,pt[i].y);	
			cvs.lineTo(pt[j].x, pt[j].y);
		}
}
//<<<<<<<<<<<<<<<<<<<<<<<<<<<<< display >>>>>>>>>>>>>>>>>>>>>>
void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);		// clear screen 
	glMatrixMode(GL_MODELVIEW); // set up rotation
	glLoadIdentity();
	glRotatef(angle,0,0,1);
	Rosette(numSides, 8);  // draw the rosette
	glutSwapBuffers(); // swap buffers for smooth animation
}
//<<<<<<<<<<<<<<<<<<<<<<< myKeys >>>>>>>>>>>>>>>>>>>>>>>>
void myKeys(unsigned char key, int x, int y)
{
	switch(key)  
	{
		case 'q': exit(0); // quit
		case 'n': numSides++; cout << numSides << endl; break;
		case 'N': numSides--; cout << numSides << endl; break;
		case 'r': delAngle +=1.0; break; //increase rotation speed
		case 'R': delAngle -=1.0; break;
	}
	display();
}
//<<<<<<<<<<<<<<<<<<<<<<<<<<< spinner >>>>>>>>>>>>>>>
void spinner(void) // the idle function
{
		angle += delAngle; // increase rotation angle
		display();
}
//<<<<<<<<<<<<<<<<<<<<< myInit >>>>>>>>>>>>>>>>>>
void myInit()
{
	glClearColor(1.0f,1.0f,1.0f,1.0f);  // background is white 
	glColor3f(0.0f,0.0f,0.0f);			// set color of stuff 
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(-10, 10,-10,10); // set window
	glViewport(0,0,screenWidth,screenHeight); //the default
}
//<<<<<<<<<<<<<<<<<<<<<< main >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
void main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowSize(screenWidth, screenHeight);
	glutInitWindowPosition(100, 100);
	glutCreateWindow("here we go");
	glutKeyboardFunc(myKeys);
	glutDisplayFunc(display);
	glutIdleFunc(spinner);
	myInit();
	glutMainLoop();
}