#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdlib.h>
#include "canvas.h"

const int screenWidth = 640;
const int screenHeight = 480;
const int maxVertices = 1000;

Canvas cvs(screenWidth, screenHeight, "Tweening two polygons");

void drawPolygon(int numVertices, Point2 vertices[])
{
  glBegin(GL_LINE_STRIP);
  for(int i = 0; i <= numVertices; i++)
    glVertex2f(vertices[i].getX(), vertices[i].getY() );
  glEnd();
  glFlush();
}

void display(void)
{
	cvs.clearScreen();
	cvs.setWindow(-5.0, 5.0, -5.0, 5.0);
	cvs.setViewport(10, 460, 10, 460);

	Point2 polyA[maxVertices];
	Point2 polyB[maxVertices];

	polyA[0].set (0,0);
	polyA[1].set (1,0);
	polyA[2].set (1,1);
	polyA[3].set (2,1);
	polyA[4].set (2,-1);
	polyA[5].set (0,-1);
	polyA[6].set (0,0);

	polyB[0].set (0,0);
	polyB[1].set (1,0);
	polyB[2].set (2,0);
	polyB[3].set (2,1);
	polyB[4].set (2,2);
	polyB[5].set (0,2);
	polyB[6].set (0,0);

	for (float j=0; j<= 1.0; j += 0.1)
	  {
	    cvs.setColor(0.0, 0.0, 1.0);
	    drawPolygon(6, polyA);
	    cvs.setColor(1.0, 0.0, 0.0);
	    drawPolygon(6, polyB);
	    cvs.setColor(j, 0.0, 1-j);
	    cvs.drawTween(polyA, polyB, 6, j);
	  }

}


int main(void)
{
	cvs.setBackgroundColor(1.0, 1.0, 1.0);
	cvs.setColor(0.0, 0.0, 1.0);
	glutDisplayFunc(display);
	glutMainLoop();
}