java/examples/Basics/Math/AdditiveWave/applet/AdditiveWave.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 AdditiveWave extends PApplet {
+
+/**
+ * Additive Wave
+ * by Daniel Shiffman. 
+ * 
+ * Create a more complex wave by adding two waves together. 
+ */
+ 
+int xspacing = 8;   // How far apart should each horizontal location be spaced
+int w;              // Width of entire wave
+int maxwaves = 4;   // total # of waves to add together
+
+float theta = 0.0f;
+float[] amplitude = new float[maxwaves];   // Height of wave
+float[] dx = new float[maxwaves];          // Value for incrementing X, to be calculated as a function of period and xspacing
+float[] yvalues;                           // Using an array to store height values for the wave (not entirely necessary)
+
+public void setup() {
+  size(200, 200);
+  frameRate(30);
+  colorMode(RGB, 255, 255, 255, 100);
+  smooth();
+  w = width + 16;
+
+  for (int i = 0; i < maxwaves; i++) {
+    amplitude[i] = random(10,30);
+    float period = random(100,300); // How many pixels before the wave repeats
+    dx[i] = (TWO_PI / period) * xspacing;
+  }
+
+  yvalues = new float[w/xspacing];
+}
+
+public void draw() {
+  background(0);
+  calcWave();
+  renderWave();
+}
+
+public void calcWave() {
+  // Increment theta (try different values for 'angular velocity' here
+  theta += 0.02f;
+
+  // Set all height values to zero
+  for (int i = 0; i < yvalues.length; i++) {
+    yvalues[i] = 0;
+  }
+ 
+  // Accumulate wave height values
+  for (int j = 0; j < maxwaves; j++) {
+    float x = theta;
+    for (int i = 0; i < yvalues.length; i++) {
+      // Every other wave is cosine instead of sine
+      if (j % 2 == 0)  yvalues[i] += sin(x)*amplitude[j];
+      else yvalues[i] += cos(x)*amplitude[j];
+      x+=dx[j];
+    }
+  }
+}
+
+public void renderWave() {
+  // A simple way to draw the wave with an ellipse at each location
+  noStroke();
+  fill(255,50);
+  ellipseMode(CENTER);
+  for (int x = 0; x < yvalues.length; x++) {
+    ellipse(x*xspacing,width/2+yvalues[x],16,16);
+  }
+}
+
+
+  static public void main(String args[]) {
+    PApplet.main(new String[] { "AdditiveWave" });
+  }
+}