java/examples/Basics/Math/PolarToCartesian/applet/PolarToCartesian.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 PolarToCartesian extends PApplet {
+
+/**
+ * PolarToCartesian
+ * by Daniel Shiffman.  
+ * 
+ * Convert a polar coordinate (r,theta) to cartesian (x,y):  
+ * x = r * cos(theta)
+ * y = r * sin(theta)
+ */
+ 
+float r;
+
+// Angle and angular velocity, accleration
+float theta;
+float theta_vel;
+float theta_acc;
+
+public void setup() {
+  size(200,200);
+  frameRate(30);
+  smooth();
+  
+  // Initialize all values
+  r = 50.0f;
+  theta = 0.0f;
+  theta_vel = 0.0f;
+  theta_acc = 0.0001f;
+}
+
+public void draw() {
+  background(0);
+  // Translate the origin point to the center of the screen
+  translate(width/2,height/2);
+  
+  // Convert polar to cartesian
+  float x = r * cos(theta);
+  float y = r * sin(theta);
+  
+  // Draw the ellipse at the cartesian coordinate
+  ellipseMode(CENTER);
+  noStroke();
+  fill(200);
+  ellipse(x,y,16,16);
+  
+  // Apply acceleration and velocity to angle (r remains static in this example)
+  theta_vel += theta_acc;
+  theta += theta_vel;
+
+}
+
+
+
+
+
+  static public void main(String args[]) {
+    PApplet.main(new String[] { "PolarToCartesian" });
+  }
+}