java/examples/Topics/Motion/Puff/applet/Puff.java

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+import processing.core.*; 
+
+import java.applet.*; 
+import java.awt.*; 
+import java.awt.image.*; 
+import java.awt.event.*; 
+import java.io.*; 
+import java.net.*; 
+import java.text.*; 
+import java.util.*; 
+import java.util.zip.*; 
+import java.util.regex.*; 
+
+public class Puff extends PApplet {
+
+/**
+ * Puff  
+ * by Ira Greenberg.  
+ * 
+ * Series of ellipses simulating a multi-segmented 
+ * organism, utilizing a follow the leader algorithm.
+ * Collision detection occurs on the organism's head, 
+ * controlling overall direction, and on the individual 
+ * body segments, controlling body shape and jitter.
+ */
+
+// for puff head
+float headX;
+float headY;
+float speedX = .7f;
+float speedY = .9f;
+
+// for puff body
+int cells = 1000;
+float[]px= new float[cells];
+float[]py= new float[cells];
+float[]radiiX = new float[cells];
+float[]radiiY = new float[cells];
+float[]angle = new float[cells];
+float[]frequency = new float[cells];
+float[]cellRadius = new float[cells];
+
+public void setup(){
+  
+  size(640, 360);
+  
+  // begin in the center
+  headX = width/2;
+  headY = height/2;
+
+  //fill body arrays
+  for (int i=0; i< cells; i++){
+    radiiX[i] = random(-7, 7); 
+    radiiY[i] = random(-4, 4);
+    frequency[i]= random(-9, 9);
+    cellRadius[i] = random(16, 30);
+  }
+  frameRate(30);
+}
+
+public void draw(){
+  background(0);
+  noStroke();
+  fill(255, 255, 255, 5);
+
+  //follow the leader
+  for (int i =0; i< cells; i++){
+    if (i==0){
+      px[i] = headX+sin(radians(angle[i]))*radiiX[i];
+      py[i] = headY+cos(radians(angle[i]))*radiiY[i];
+    } 
+    else{
+      px[i] = px[i-1]+cos(radians(angle[i]))*radiiX[i];
+      py[i] = py[i-1]+sin(radians(angle[i]))*radiiY[i];
+
+      //check collision of body
+      if (px[i] >= width-cellRadius[i]/2 || px[i] <= cellRadius[i]/2){
+        radiiX[i]*=-1;
+        cellRadius[i] = random(1, 40);
+        frequency[i]= random(-13, 13);
+      }
+      if (py[i] >= height-cellRadius[i]/2 || py[i] <= cellRadius[i]/2){
+        radiiY[i]*=-1;
+        cellRadius[i] = random(1, 40);
+        frequency[i]= random(-9, 9);
+      }
+    }
+    // draw puff
+    ellipse(px[i],  py[i],  cellRadius[i],  cellRadius[i]);
+    // set speed of body
+    angle[i]+=frequency[i];
+  }
+
+  // set velocity of head
+  headX+=speedX;
+  headY+=speedY;
+
+  //check boundary collision of head
+  if (headX >= width-cellRadius[0]/2 || headX <=cellRadius[0]/2){
+    speedX*=-1;
+  }
+  if (headY >= height-cellRadius[0]/2 || headY <= cellRadius[0]/2){
+    speedY*=-1;
+  }
+}
+
+
+  static public void main(String args[]) {
+    PApplet.main(new String[] { "Puff" });
+  }
+}