Processing Sketch - Flames!

sketch_aug31b.pde

/**
 * Flames. Generates some flames by using gradients (with basic 
 * spline math) and Perlin noise (for generating the flame 
 * height).
 */

/** Flame outer color */
color startCol = color(100, 0, 210);
/** Flame inner color */
color endCol = color(200, 150, 255);

void setup() {
  int w = 150;
  int h = 150;
  frame.removeNotify();
  frame.setUndecorated(true);
  frame.addNotify(); 
  size(w, h);
  background(backCol);
  pgCurrent = createGraphics(w, h, P3D);
  pgPrevious = createGraphics(w, h, P3D);
  gradient = new Gradient(startCol, endCol);
}

Gradient gradient;
PGraphics pgCurrent;
PGraphics pgPrevious;
int col = 255;
int fadeFalloff = 25;
float wFactor = 0.02;
float time = 0;
float timeScale = 0.05;
int backCol = 50;
int yOffset = -5;

void draw() {
  drawFlames(pgCurrent, pgPrevious);
  image(pgCurrent, 0, 0);
}

void drawFlames(PGraphics pg, PGraphics pgOld) {
  pgOld.beginDraw();
  pgOld.image(pg, 0, 0);
  pgOld.endDraw();
  pg.beginDraw();
  pg.image(pgOld, 1, yOffset);
  pg.fill(backCol, fadeFalloff);
  pg.noStroke();
  pg.rect(0, 0, width, height);
  for(int w = 0; w < width; w++) {
    float h = noise(w*wFactor, time)*height;
    for (int y = (int)h; y<height; y++) {
      float t = ((y)-h)/((float)height-h);
      pg.stroke(gradient.getAt(t));
      pg.point(w, y);
    }
  }
  time += timeScale;
  pg.endDraw();
}

class Gradient {
  color start;
  color end;
  Gradient(color start, color end) {
    this.start = start;
    this.end = end;
  }
  
  public color getAt(float t) {
    float r = spline(red(start), red(end), t);
    float g = spline(green(start), green(end), t);
    float b = spline(blue(start), blue(end), t);
    return color(r, g, b);
  }
  
  private float spline(float a, float b, float t) {
    return a+t*(b-a);
  }
}