// Seung Joon Choi
// http://epicure.graffity.net
// epicure@hanmail.net
// 2005.10.14.

//-----------------------
int sl_width;
int sl_height;

PImage canvas;
float[] hmap;
//-----------------------
float sss = 0;
int kkk = 0;

color SL(float s, float t)
{
  float r = 1 - dist(0.5, 0.5, sss*0.01, sss*0.01);
  float vs = sin(3*TWO_PI * s);
  float vt = sin(3*TWO_PI * t);    
  float check = vs*vt > 0 ? 1 : 0;
  float theta = atan2(0.5 - t, 0.5 - s); 
  
  //s = s + 0.2 *sin(sss * 0.01 * PI) *cos(5*PI * t);
  //t = t + 0.2 *cos(sss * 0.01 * PI) *sin(5*PI * s);
    
  float dx = 0.5 - s;
  float dy = 0.5 - t;
  float a = r * 0.5;
  float k = 0.25;
  float g = k*k / (dx*dx + dy*dy - a*a);
  float r2 = abs(g);
  float v = check - r2*cos(TWO_PI*r2 + 6*theta+sss);

    
  return color(sss * 0.01, v, v, v * 0.05);
}

float SLH(float s, float t)
{
  float v = 0;  
  float v1 = s + 0.1 * cos(4 * PI * t);
  float v2 = sin(6 * PI * v1 - PI * 0.5 + sss);
  float d = 1 - dist(0.5, 0.5, s, t);
  
  v = v2 * d;  

  
  return v;
}

void buildCanvas()
{
  noiseDetail(3, sss);
  canvas.loadPixels();
  for(int iy = 0; iy < sl_height; iy++)
  for(int ix = 0; ix < sl_width; ix++)
  {
    float s = (float)ix / (float)(sl_width-1);
    float t = (float)iy / (float)(sl_height-1);
    
    canvas.pixels[iy * sl_width + ix] = SL(s, t);    
  }
  canvas.updatePixels();
  //sss += 0.0025;
  sss += 0.2;
}

void buildHeightField()
{
  for(int iy = 0; iy < sl_height; iy++)
  for(int ix = 0; ix < sl_width; ix++)
  {
    float s = (float)ix / (float)(sl_width-1);
    float t = (float)iy / (float)(sl_height-1);
    
    hmap[iy * sl_width + ix] = SLH(s, t);    
  }
}

void drawHField(float max_h)
{
  float v = 0;
  fill(0.5, 1, 0.2);  
  
  float sz = 80;
  float off_x = sl_width * 0.5;
  float off_y = sl_height * 0.5;
  for(int iy = 0; iy < sl_height - 1; iy++)
  {
    /*
    beginShape(QUAD_STRIP);
    texture(canvas);
    for(int ix = 0; ix < sl_width; ix++)
    {
      float s = (float)ix / (float)(sl_width-1);
      float t = (float)iy / (float)(sl_height-1);
      v = hmap[iy * sl_width + ix];
      normal(0, 0, 1);
      vertex((ix - off_x) * sz, (iy - off_y) * sz, v * 30, s, t);
      v = hmap[(iy + 1) * sl_width + ix];
      normal(0, 0, 1);
      vertex((ix - off_x) * sz, (iy + 1 - off_y) * sz, v * 30, s, t);
    }
    endShape();
    */
    beginShape(QUAD_STRIP);
    for(int ix = 0; ix < sl_width; ix++)
    {
      v = hmap[iy * sl_width + ix];
      normal(0, 0, 1);
      vertex((ix - off_x) * sz, (iy - off_y) * sz, v * max_h);
      v = hmap[(iy + 1) * sl_width + ix];
      normal(0, 0, 1);
      vertex((ix - off_x) * sz, (iy + 1 - off_y) * sz, v * max_h);      
    }
    endShape();
  }
}