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diff --git a/grotto/grotto.pde b/grotto/grotto.pde
new file mode 100644
index 0000000..3f5ddb0
--- /dev/null
+++ b/grotto/grotto.pde
@@ -0,0 +1,146 @@
+import yash.oklab.*;  
+
+// Configuration parameters
+final int WIDTH = 1000;
+final int HEIGHT = 1000;
+final float NOISE_SCALE = 0.5;
+final float NOISE_AMPLITUDE = 100;
+final int BASE_RADIUS = 130;
+final int PARTICLES_PER_FRAME = 10000;
+final float SPRAY_RADIUS = 2;
+final int RIDGES = 3;
+final int centerX = WIDTH / 2;
+final int centerY = HEIGHT / 2;
+final int BACKGROUND = 0;
+
+// Global variables
+String finalImagePath = null;
+float m_noiseOffset = 0;
+float m_hue = 0;
+int m_fillColor = 0;
+
+void settings() {
+  size(WIDTH, HEIGHT, P2D);
+  smooth(8);
+}
+
+void setup() {
+  colorMode(RGB, 255, 255, 255);
+  noiseDetail(4, 0.5);
+  Ok.p = this;
+  resetSketch();
+}
+
+float noisyRadius(float baseRadius, float angle, float noiseOffset) {
+  // Convert angle to polar coordinates relative to center
+  float xoff = cos(angle) + 1;
+  float yoff = sin(angle) + 1;
+  
+  // Calculate the noisy radius at this angle
+  return baseRadius + map(noise(xoff * NOISE_SCALE, yoff * NOISE_SCALE, noiseOffset), 0, 1, -NOISE_AMPLITUDE, NOISE_AMPLITUDE);
+}
+
+boolean insideRadius(float x, float y, float radius) {
+  // Check if the point (x, y) is outside the radius
+  float dist = dist(x, y, centerX, centerY);
+  return dist < radius;
+}
+
+void drawRidge(float radius, float noiseOffset) {
+  loadPixels();
+  for (int x = 0; x < width; x++) {
+    for (int y = 0; y < height; y++) {
+      float dx = x - centerX;
+      float dy = y - centerY;
+      
+
+      float angle = atan2(dy, dx);
+      float dist = sqrt(dx*dx + dy*dy);
+      
+      float noisyRadius = noisyRadius(radius, angle, noiseOffset);
+      float distFromBoundary = abs(dist - noisyRadius);
+
+      if (insideRadius(x, y, noisyRadius)) {
+        continue;
+      }
+      
+      // Create smooth falloff
+      float intensity = constrain(map(distFromBoundary, 0, 2*NOISE_AMPLITUDE, 1, 0), 0, 1);
+      //intensity = intensity * intensity; // Square for smoother falloff
+      
+      int loc = x + y * width;
+      pixels[loc] = lerpColor(BACKGROUND, m_fillColor, intensity * 0.4);
+    }
+  }
+  updatePixels();
+  for (int i = 0; i < PARTICLES_PER_FRAME;) {
+    // Focus particles around the circle boundary for efficiency
+    float angle = random(TWO_PI);
+    float noisyRadius = noisyRadius(radius, angle, noiseOffset);
+    float finalRadius = noisyRadius + randomGaussian() * NOISE_AMPLITUDE * 0.5;
+    float rx = centerX + cos(angle) * finalRadius;
+    float ry = centerY + sin(angle) * finalRadius;
+    if (insideRadius(rx, ry, noisyRadius)) {
+      continue;
+    }
+    circle(rx + randomGaussian() * SPRAY_RADIUS, 
+           ry + randomGaussian() * SPRAY_RADIUS, 
+           random(2, 3));
+    i++;
+  }
+}
+
+void draw() {
+  // Draw background with low opacity to create a fading effect
+  fill(BACKGROUND);
+  rect(0, 0, width, height);
+  // Draw particles
+  noStroke();
+  
+  for (int i = 0; i < RIDGES; i++) {
+    // H = Hue (0-360), S = Saturation (0-100), V = Value (0-100), L = Lightness (0-100) (unused here), A = Alpha (0-100).
+    // Set the fill color using the Ok.HSV function, which converts HSV values to a color
+    m_fillColor = Ok.HSV(
+      m_hue, // Hue: the base hue value, which is randomized in resetSketch()
+      80, // ((float)i + 1.0f / (float)RIDGES) * 100.0f, // Saturation: increases with each ridge, creating a gradient effect
+      ((float)i + 1.0f / (float)RIDGES) * 100.0f, // Brightness: also increases with each ridge for a similar gradient effect
+      30 // Alpha: transparency level, set to 30 for a subtle blending effect
+    );
+    fill(m_fillColor);
+    drawRidge(BASE_RADIUS + 100 * i, m_noiseOffset + 10 * i);
+  }
+  
+  m_noiseOffset += 0.05;
+}
+
+void keyPressed() {
+  if (key == 's' || key == 'S') {
+    saveImage();
+  } else if (key == ENTER || key == '\n') {
+    resetSketch();
+  }
+}
+
+void saveImage() {
+  String filename = year() + "-" + month() + "-" + day() + "-" + hour() + "-" + minute() + "-" + second() + ".png";
+  if (finalImagePath != null) {
+    // Copy the temporary file to the new filename
+    File source = new File(sketchPath(finalImagePath));
+    File dest = new File(sketchPath(filename));
+    try {
+      java.nio.file.Files.copy(source.toPath(), dest.toPath());
+    } catch (IOException e) {
+      println("Error saving file: " + e.getMessage());
+    }
+  } else {
+    save(filename);
+  }
+}
+
+void resetSketch() {
+  background(0);
+  frameCount = 0;
+  finalImagePath = null;
+  m_hue = random(360.0f);
+  loop();
+}
diff --git a/grotto/readme.md b/grotto/readme.md
new file mode 100644
index 0000000..7de0726
--- /dev/null
+++ b/grotto/readme.md
@@ -0,0 +1,3 @@
+# Grotto
+
+Inspired by Jean-Marie Chupin.
diff --git a/todo.md b/todo.md
index d288c44..ab47ccb 100644
--- a/todo.md
+++ b/todo.md
@@ -9,10 +9,6 @@
     - [x] Use lib in projects
     - [x] Create git repo
     - [x] in generative repo, add a 'dependency' section linking back to the PaperAndPencil repo
-  - [ ] Color
-    - [ ] Create lib
-    - [ ] Create example project
-    - [ ] Use lib in projects
   - [ ] Utils (saving, etc.)
     - [ ] Create lib
     - [ ] Create example project
@@ -20,3 +16,4 @@
 - [ ] colorGrowth:
   - [ ] Try it with a more complex color system
 - [ ] grotto
+  - [ ] try reversing the drawing process, creating dark shadows instead of light ridges