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/*
*  AirstreamFilter.cpp
*
*  Created by Daisuke Nogami on Sep, 05.
*  opyright 2005 Daisuke Nogami [null-null.net]. Some rights reserved.
*/
 
#include "stdafx.h"
#include "AirstreamFilter.h"
 
// param
#define DAMPING 0.95
#define MASS 30.0
#define SPRING_CONSTANT 0.2
 
#define BLOWING_INTERVEL 30
 
AirstreamFilter::AirstreamFilter(){
  dirX = nextDirX = 0;
  dirY = nextDirY = 0;
  srcY = nextSrcY = 0;
  timer = 0;
 
  damp = DAMPING;
  mass = MASS;
  k = SPRING_CONSTANT;
 
  velx = 0.0;
  vely = 0.0;
  velsrcy = 0.0;
  accel = 0;
  force = 0;
 
  wind_dir = 0; // -->
  wind_speed = 0;
 
  // initialize random seed
  srand( time( NULL ) );
}
 
// parameters:
//  wind_dir - wind direction [-0.5~0.5]
//  wind_spped - wind power
void AirstreamFilter::sync( float wind_dir, float wind_spped ){
  this->wind_dir = wind_dir;
  this->wind_speed = wind_spped;
}
 
void AirstreamFilter::update(){
  if( timer++ > BLOWING_INTERVEL ){
    nextDirX = ((float)rand()/RAND_MAX-0.5+wind_dir)*1024;
    nextDirY = ((float)rand()/RAND_MAX-0.5)*768;
    nextSrcY = (float)rand()/RAND_MAX*768;
    timer = 0;
  }
 
  // x axis
  force = -k * ( dirX - nextDirX );  //f=-kx
  accel = force/mass;  //f=ma == a=f/m
  velx = damp * ( velx + accel );
  dirX += velx;
 
  // y axis
  force = -k * ( dirY - nextDirY );  //f=-ky
  accel = force/mass;  //f=ma == a=f/m
  vely = damp * ( vely + accel );
  dirY += vely;
 
  // y axis (src)
  force = -k * ( srcY - nextSrcY );  //f=-ky
  accel = force/mass;  //f=ma == a=f/m
  velsrcy = damp * ( vely + accel );
  srcY += velsrcy;
}
 
void AirstreamFilter::mappingTo( CellSet* cellset ){
  int x, y, i, j;
  float alpha = 0, beta = 0;
 
  // wind source power
  float windsrc_pow = 0.02*wind_speed; // to cell A
  float windsrc_pow_b = windsrc_pow*0.8; // to cell B
 
  // -->
  if( wind_dir >= 0 ){
    // set airstream
    for( y = 0; y < cellset->hdiv; y++ ){
      i = y*cellset->wdiv;
 
      alpha = (1-(float)abs(srcY-cellset->cells_a[i].ypos)/768)+0.3;
      alpha = (alpha*alpha) * windsrc_pow;
 
      beta = (1-(float)abs(srcY-cellset->cells_b[i].ypos)/768)+0.3;
      beta = (beta*beta) * windsrc_pow_b;
 
      cellset->cells_a[i].next( dirX*alpha, dirY*alpha );
      cellset->cells_b[i].next( dirX*beta, dirY*beta );
    }
 
    // transmission
    for( y = 0; y < cellset->hdiv; y++ ){
      for( x = cellset->wdiv-1; x >= 1; x-- ){
        i = x+y*cellset->wdiv;
        j = (x-1)+y*cellset->wdiv;
 
        cellset->cells_a[i].next( cellset->cells_a[j].nextx, cellset->cells_a[j].nexty );
        cellset->cells_b[i].next( cellset->cells_b[j].nextx, cellset->cells_b[j].nexty );
      }
    }
  }
  // <--
  else{
    // set airstream
    for( y = 0; y < cellset->hdiv; y++ ){
      i = (cellset->wdiv-1)+y*cellset->wdiv;
 
      alpha = (1-(float)abs(srcY-cellset->cells_a[i].ypos)/768)+0.3;
      alpha = (alpha*alpha) * windsrc_pow;
 
      beta = (1-(float)abs(srcY-cellset->cells_b[i].ypos)/768)+0.3;
      beta = (beta*beta) * windsrc_pow_b;
 
      cellset->cells_a[i].next( dirX*alpha, dirY*alpha );
      cellset->cells_b[i].next( dirX*beta, dirY*beta );
    }
 
    // transmission
    for( y = 0; y < cellset->hdiv; y++ ){
      for( x = 0; x < cellset->wdiv-1; x++ ){
        i = x+y*cellset->wdiv;
        j = (x+1)+y*cellset->wdiv;
 
        cellset->cells_a[i].next( cellset->cells_a[j].nextx, cellset->cells_a[j].nexty );
        cellset->cells_b[i].next( cellset->cells_b[j].nextx, cellset->cells_b[j].nexty );
      }
    }
  }
}