Two new examples Star and Regular Polygon for Basics

java/examples/Basics/Form/PieChart/PieChart.pde

@@ -1,28 +1,28 @@
 /**
  * Pie Chart  
- * By Ira Greenberg 
  * 
  * Uses the arc() function to generate a pie chart from the data
  * stored in an array. 
  */
 
-
-float diameter;
 int[] angles = { 30, 10, 45, 35, 60, 38, 75, 67 };
-float lastAngle = 0;
 
 void setup() {
   size(640, 360);
-  background(100);
   noStroke();
-  diameter = min(width, height) * 0.75;
   noLoop();  // Run once and stop
 }
 
-
 void draw() {
-  for (int i = 0; i < angles.length; i++) {
-    fill(angles[i] * 3.0);
+  background(100);
+  pieChart(300, angles);
+}
+
+void pieChart(float diameter, int[] data) {
+  float lastAngle = 0;
+  for (int i = 0; i < data.length; i++) {
+    float gray = map(i, 0, data.length, 0, 255);
+    fill(gray);
     arc(width/2, height/2, diameter, diameter, lastAngle, lastAngle+radians(angles[i]));
     lastAngle += radians(angles[i]);
   }

java/examples/Basics/Form/RegularPolygon/RegularPolygon.pde

@@ -0,0 +1,46 @@
+/**
+ * Regular Polygon
+ * 
+ * What is your favorite? Pentagon? Hexagon? Heptagon? 
+ * No? What about the icosagon? The polygon() function 
+ * created for this example is capable of drawing any 
+ * regular polygon. Try placing different numbers into the 
+ * polygon() function calls within draw() to explore. 
+ */
+
+void setup() {
+  size(640, 360);
+}
+
+void draw() {
+  background(102);
+  
+  pushMatrix();
+  translate(width*0.2, height*0.5);
+  rotate(frameCount / 200.0);
+  polygon(0, 0, 82, 3); 
+  popMatrix();
+  
+  pushMatrix();
+  translate(width*0.5, height*0.5);
+  rotate(frameCount / 50.0);
+  polygon(0, 0, 80, 20); 
+  popMatrix();
+  
+  pushMatrix();
+  translate(width*0.8, height*0.5);
+  rotate(frameCount / -100.0);
+  polygon(0, 0, 70, 7); 
+  popMatrix();
+}
+
+void polygon(float x, float y, float radius, int npoints) {
+  float angle = TWO_PI / npoints;
+  beginShape();
+  for (float a = 0; a < TWO_PI; a += angle) {
+    float sx = x + cos(a) * radius;
+    float sy = y + sin(a) * radius;
+    vertex(sx, sy);
+  }
+  endShape(CLOSE);
+}

java/examples/Basics/Form/Star/Star.pde

@@ -0,0 +1,48 @@
+/**
+ * Star
+ * 
+ * The star() function created for this example is capable of drawing a
+ * wide range of different forms. Try placing different numbers into the 
+ * star() function calls within draw() to explore. 
+ */
+
+void setup() {
+  size(640, 360);
+}
+
+void draw() {
+  background(102);
+  
+  pushMatrix();
+  translate(width*0.2, height*0.5);
+  rotate(frameCount / 200.0);
+  star(0, 0, 5, 70, 3); 
+  popMatrix();
+  
+  pushMatrix();
+  translate(width*0.5, height*0.5);
+  rotate(frameCount / 50.0);
+  star(0, 0, 80, 100, 40); 
+  popMatrix();
+  
+  pushMatrix();
+  translate(width*0.8, height*0.5);
+  rotate(frameCount / -100.0);
+  star(0, 0, 30, 70, 5); 
+  popMatrix();
+}
+
+void star(float x, float y, float radius1, float radius2, int npoints) {
+  float angle = TWO_PI / npoints;
+  float halfAngle = angle/2.0;
+  beginShape();
+  for (float a = 0; a < TWO_PI; a += angle) {
+    float sx = x + cos(a) * radius2;
+    float sy = y + sin(a) * radius2;
+    vertex(sx, sy);
+    sx = x + cos(a+halfAngle) * radius1;
+    sy = y + sin(a+halfAngle) * radius1;
+    vertex(sx, sy);
+  }
+  endShape(CLOSE);
+}