cloth.h

#ifndef CLOTH_H
#define CLOTH_H

#include <iostream>
#include "cvec.h"
#include "geometry.h"

class Cloth
{
  int height;
  int width;
  int ballWidth;
  int ballHeight;
  int numBalls;
  int numVertices;

  std::vector<Ball> balls;
  std::vector<Spring> springs;

  std::vector<VertexPN> vertices;

  void newSpring(Ball *ball1, Ball *ball2) {
    springs.push_back(Spring(ball1,ball2));
  }

  Ball* getBallAt (int x, int y) {
    return &balls[y * ballWidth + x];
  }

  void updateVertices() {
    updateNormals();

    std::vector<VertexPN>::iterator it = vertices.begin();

    for(int i = 0; i < ballWidth - 1 ; i++) 
      for(int j = 0; j < ballHeight - 1; j++)
      {
        *it = VertexPN(getBallAt(i+1,j)->getPos(), getBallAt(i+1,j)->getNormal().normalize());
        ++it;
        *it = VertexPN(getBallAt(i,j)->getPos(), getBallAt(i,j)->getNormal().normalize());
        ++it;
        *it = VertexPN(getBallAt(i,j+1)->getPos(), getBallAt(i,j+1)->getNormal().normalize());
        ++it;
        *it = VertexPN(getBallAt(i+1,j+1)->getPos(), getBallAt(i+1,j+1)->getNormal().normalize());
        ++it;
        *it = VertexPN(getBallAt(i+1,j)->getPos(), getBallAt(i+1,j)->getNormal().normalize());
        ++it;
        *it = VertexPN(getBallAt(i,j+1)->getPos(), getBallAt(i,j+1)->getNormal().normalize());
        ++it;
      }
  }

  void updateNormals() {
    for (int i = 0; i < ballWidth-1; i++) {
      for (int j = 0; j < ballHeight-1; j++) {
        Cvec3 normal;

        normal = triNorm(getBallAt(i+1,j), getBallAt(i,j),getBallAt(i,j+1));
        getBallAt(i+1,j)->addNormal(normal);
        getBallAt(i,j)->addNormal(normal);
        getBallAt(i,j+1)->addNormal(normal);

        normal = triNorm(getBallAt(i+1,j+1), getBallAt(i+1,j),getBallAt(i,j+1));
        getBallAt(i+1,j+1)->addNormal(normal);
        getBallAt(i+1,j)->addNormal(normal);
        getBallAt(i,j+1)->addNormal(normal);
      }
    }
  }

  //calculates the normal of the traingle formed by three balls
  Cvec3 triNorm(Ball *ball1, Ball *ball2, Ball *ball3) {
    return cross((ball2->getPos() - ball1->getPos()),(ball3->getPos() - ball1->getPos()));
  }

public:
  Cloth () {}

  std::vector<VertexPN> getVertices() {
    return vertices;
  }

  void loadDimensions(int w, int h, int bw, int bh) {
    width = w;
    height = h;
    ballWidth = bw;
    ballHeight = bh;

    numBalls = bw*bh;
    numVertices = numBalls * 6;

    balls.resize(numBalls);
    vertices.resize(numVertices * 6);

    for (int x = 0; x < ballWidth; ++x)
      for (int y=0; y < ballHeight; ++y)
      {
        float pos2;
        if (x == 0 || x == ballWidth-1 || y == 0 || y == ballHeight-1)
          pos2 = height / (float)ballHeight / 2;
        else
          pos2 = 0;
        Cvec3 position = Cvec3(width * (x / (float)ballWidth),pos2,height * (y / (float)ballHeight));
          balls[y * ballWidth + x] = Ball(position+Cvec3(0,4,0));
        balls[y * ballWidth + x].setAccel(Cvec3(0.,-0.1,0.));
      }

    //connects all balls that are distance 1 apart with springs
    for(int i = 0; i < ballWidth; i++)
			for(int j = 0; j < ballHeight; j++)
			{
				if (i < ballWidth - 1)
          newSpring(getBallAt(i,j),getBallAt(i+1,j));
				if (j < ballHeight - 1)
          newSpring(getBallAt(i,j),getBallAt(i,j+1));
				if (i < ballWidth-1 && j < ballHeight-1) 
          newSpring(getBallAt(i,j),getBallAt(i+1,j+1));
				if (i < ballWidth-1 && j < ballHeight-1) 
          newSpring(getBallAt(i+1,j),getBallAt(i,j+1));
			}
    
    //connects all balls that are distance 2 apart with springs
		for(int i = 0; i < ballWidth; i++)
			for(int j = 0; j < ballHeight; j++)
			{
				if (i < ballWidth - 2)
          newSpring(getBallAt(i,j),getBallAt(i+2,j));
				if (j < ballHeight - 2)
          newSpring(getBallAt(i,j),getBallAt(i,j+2));
				if (i < ballWidth - 2 && j < ballHeight - 2)
          newSpring(getBallAt(i,j),getBallAt(i+2,j+2));
				if (i < ballWidth - 2 && j < ballHeight - 2)
          newSpring(getBallAt(i+2,j),getBallAt(i,j+2));			
      }

    //fixes the movment of the four corners
    getBallAt(0,0)->fixMovement();
    getBallAt(ballWidth-1,0)->fixMovement();
    getBallAt(0,ballHeight-1)->fixMovement();
    getBallAt(ballWidth-1,ballHeight-1)->fixMovement();

    updateVertices();
  }

  //unfixes all four corners
  void unfix()
  {
    getBallAt(0,0)->unfixMovement(); 
    getBallAt(ballWidth-1,0)->unfixMovement();
    getBallAt(0,ballHeight-1)->unfixMovement();
    getBallAt(ballWidth-1,ballHeight-1)->unfixMovement();
  }

  //unfixes two corners
  void unfix2()
  {
    getBallAt(0,ballHeight-1)->unfixMovement();
    getBallAt(ballWidth-1,ballHeight-1)->unfixMovement();
  }


  void collision(Cvec3 center, float radius, float groundY)
	{
   for (int i = 0, n = balls.size(); i < n; i++)
	 {
     //check for collisions with balls 
     float bufferedRadius = radius + .05;
		 Cvec3 toCenter = balls[i].getPos() - center;

		 float l = toCenter.length();

		 if (l < bufferedRadius) 
       balls[i].movePos(toCenter.normalize() * (bufferedRadius-l));
      
     //check for colisions with ground
     if (balls[i].getPos()[1] < groundY)
     {
       balls[i].setPos(Cvec3(balls[i].getPos()[0],groundY,balls[i].getPos()[2]));
       balls[i].fixMovement();
     }
	  }
    updateVertices();
	}

	void timeStep()
	{
	  //at every timestep, constrain the springs 10 times for more rigidity
    for(int i = 0; i < 10; i++)
			for (int j = 0, n = springs.size(); j < n; j++)
				springs[j].calcSpring();

		for (int i = 0, n = balls.size(); i < n; i++)
			balls[i].timeStep();
	}

	void addForce(Cvec3 f)
	{
		for (int i = 0, n = balls.size(); i < n; i++) 
    {
			balls[i].newForce(f);
      balls[i].resetNormal();
    }
	}

  void addWind(Cvec3 dir)
	{
		for(int i = 0; i < ballWidth-1; i++)
			for(int j = 0; j < ballHeight-1; j++)
			{
        //add wind for first triangle
        Cvec3 n = triNorm(getBallAt(i+1,j),getBallAt(i,j),getBallAt(i,j+1));
		    Cvec3 f = n * dot(n.normalize(),dir);
		    getBallAt(i+1,j)->newForce(f);
		    getBallAt(i,j)->newForce(f);
		    getBallAt(i,j+1)->newForce(f);

        //add wind for second triangle
        n = triNorm(getBallAt(i+1,j+1),getBallAt(i+1,j),getBallAt(i,j+1));
		    f = n * dot(n.normalize(),dir);
		    getBallAt(i+1,j+1)->newForce(f);
		    getBallAt(i+1,j)->newForce(f);
		    getBallAt(i,j+1)->newForce(f);
			}
	}

  void removeWind(Cvec3 dir)
	{
		for(int i = 0; i < ballWidth-1; i++)
			for(int j = 0; j < ballHeight-1; j++)
			{
        //remove wind for first triangle
        Cvec3 n = triNorm(getBallAt(i+1,j),getBallAt(i,j),getBallAt(i,j+1));
		    Cvec3 f = n * dot(n.normalize(),dir);
		    getBallAt(i+1,j)->minusForce(f);
		    getBallAt(i,j)->minusForce(f);
		    getBallAt(i,j+1)->minusForce(f);

        //remove wind for second triangle
        n = triNorm(getBallAt(i+1,j+1),getBallAt(i+1,j),getBallAt(i,j+1));
		    f = n * dot(n.normalize(),dir);
		    getBallAt(i+1,j+1)->minusForce(f);
		    getBallAt(i+1,j)->minusForce(f);
		    getBallAt(i,j+1)->minusForce(f);
			}
	}
};

#endif