//#include <GL/glu.h>

#include <windows.h>
#include <fstream>
#include <vector>

#include <GL/glut.h> // gl.h and glu.h are already included in glut.h

using namespace std;

#define MAX_N 1004

ifstream fiA("A.txt");
ifstream fiB("B.txt");

float** A;
float** B;
int numberOfVertexes;

void init() {
	// select clearing (background) color
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0, 800.0, 0.0, 600.0);
}

void addPoint(float** shape,int n,int k)
{
	int interval = n/k;
	for (int i=n;i<n+k;i++)
		shape[i] = new float[2];
	int i=0;
	int d=interval;
	vector<float> points[2];
	while (i<n)
	{
		points[0].push_back(shape[i][0]);
		points[1].push_back(shape[i][1]);
		d--;
		if (d==0&&k!=0)
		{
			int nexti=(i+1)%n;
			float nx=(shape[i][0]+shape[nexti][0])/(2.0);
			float ny=(shape[i][1]+shape[nexti][1])/(2.0);
			points[0].push_back(nx);
			points[1].push_back(ny);
			//points[0].push_back(shape[nexti][0]);
			//points[1].push_back(shape[nexti][1]);
			k--;
			d = interval;
		}
	}
	for (int i=0;i<n+k;i++)
	{
		for (int j=0;j<2;j++)
		shape[i][j] = points[i][j];
	}
}

void initShape() {
	int n,m;
	fiA>>n;
	fiB>>m;
	A = new float*[n];
	B = new float*[m];
	for (int i=0;i<n;i++)
	{
		A[i] = new float[2];
		fiA>>A[i][0]>>A[i][1];
	}
    for (int i = 0; i < m;i++)
    {
    	B[i] = new float[2];
    	fiB>>B[i][0]>>B[i][1];
    }
	if (n>m)
	{
		addPoint(B,m,(n-m));
	}
	else
	addPoint(A,n,(m-n));
	numberOfVertexes = max(n,m);
}

float tweening(float a, float b, float t) {
	return (1-t)*a + t*b;
}

void drawTweening(float** A, float** B, int n, float t) {
	glBegin(GL_LINE_LOOP);
	for (int i = 0; i < n; ++i) {
		float Px = tweening(A[i][0], B[i][0], t);
		float Py = tweening(A[i][1], B[i][1], t);
		glVertex2f(Px, Py);
	}
	glEnd();
	glFlush();
}

void display(void) {
	for (float t = 0.0, deltaT = 0.01; ; t += deltaT) {
		glClear(GL_COLOR_BUFFER_BIT);
		drawTweening(A, B, numberOfVertexes, t);
		glutSwapBuffers();
		if (t >= 1.0 || t < 0.0) deltaT = -deltaT;
		Sleep(50);
	}
}

int main(int argc, char** argv) {

   	glutInit(&argc, argv);

   	// single buffer and RGBA
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

	// window size
	glutInitWindowSize(800, 600);

	// window position
	glutInitWindowPosition(100, 100);

	// title bar
	glutCreateWindow("Tweening");

	// call initialization routines
	init();

	initShape();

	// Register callback function to display graphics
	glutDisplayFunc(display);

	// Enter main loop and process events
	glutMainLoop();
}