java/examples/Topics/Interaction/Reach1/applet/Reach1.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 Reach1 extends PApplet {
+
+/**
+ * Reach 1. 
+ * Based on code from Keith Peters (www.bit-101.com)
+ * 
+ * The arm follows the position of the mouse by
+ * calculating the angles with atan2(). 
+ */
+
+ 
+float x = 100;
+float y = 100;
+float x2 = 100;
+float y2 = 100;
+float segLength = 30;
+
+public void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0f);
+  stroke(0, 100);
+}
+
+public void draw() {
+  background(226);
+  
+  float dx = mouseX - x;
+  float dy = mouseY - y;
+  float angle1 = atan2(dy, dx);  
+  
+  float tx = mouseX - cos(angle1) * segLength;
+  float ty = mouseY - sin(angle1) * segLength;
+  dx = tx - x2;
+  dy = ty - y2;
+  float angle2 = atan2(dy, dx);  
+  x = x2 + cos(angle2) * segLength;
+  y = y2 + sin(angle2) * segLength;
+  
+  segment(x, y, angle1); 
+  segment(x2, y2, angle2); 
+}
+
+public void segment(float x, float y, float a) {
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}
+
+
+  static public void main(String args[]) {
+    PApplet.main(new String[] { "Reach1" });
+  }
+}