Initial Commit

Java/Processing/processing-3.3.6/modes/java/examples/Basics/Math/Arctangent/Arctangent.pde

@@ -0,0 +1,57 @@
+/**
+ * Arctangent. 
+ * 
+ * Move the mouse to change the direction of the eyes. 
+ * The atan2() function computes the angle from each eye 
+ * to the cursor. 
+ */
+ 
+Eye e1, e2, e3;
+
+void setup() {
+  size(640, 360);
+  noStroke();
+  e1 = new Eye( 250,  16, 120);
+  e2 = new Eye( 164, 185,  80);  
+  e3 = new Eye( 420, 230, 220);
+}
+
+void draw() {
+  background(102);
+  
+  e1.update(mouseX, mouseY);
+  e2.update(mouseX, mouseY);
+  e3.update(mouseX, mouseY);
+
+  e1.display();
+  e2.display();
+  e3.display();
+}
+
+class Eye {
+  int x, y;
+  int size;
+  float angle = 0.0;
+  
+  Eye(int tx, int ty, int ts) {
+    x = tx;
+    y = ty;
+    size = ts;
+ }
+
+  void update(int mx, int my) {
+    angle = atan2(my-y, mx-x);
+  }
+  
+  void display() {
+    pushMatrix();
+    translate(x, y);
+    fill(255);
+    ellipse(0, 0, size, size);
+    rotate(angle);
+    fill(153, 204, 0);
+    ellipse(size/4, 0, size/2, size/2);
+    popMatrix();
+  }
+}
+