From 2fb959f208da22bacab479bfb35444d13a537f90 Mon Sep 17 00:00:00 2001
From: Daniel Shiffman <daniel@shiffman.net>
Date: Wed, 23 Jul 2014 10:06:52 -0400
Subject: [PATCH] exercise I.3

---
 chp6_agents/NOC_6_07_Separation/Vehicle.pde   |  6 +--
 .../Exercise_I_3_Walker_To_Mouse.pde          | 20 ++++++++
 .../Exercise_I_3_Walker_To_Mouse/Walker.pde   | 49 +++++++++++++++++++
 3 files changed, 71 insertions(+), 4 deletions(-)
 create mode 100644 introduction/Exercise_I_3_Walker_To_Mouse/Exercise_I_3_Walker_To_Mouse.pde
 create mode 100644 introduction/Exercise_I_3_Walker_To_Mouse/Walker.pde

diff --git a/chp6_agents/NOC_6_07_Separation/Vehicle.pde b/chp6_agents/NOC_6_07_Separation/Vehicle.pde
index f0a5ddb9..d3e93d03 100644
--- a/chp6_agents/NOC_6_07_Separation/Vehicle.pde
+++ b/chp6_agents/NOC_6_07_Separation/Vehicle.pde
@@ -50,10 +50,8 @@ class Vehicle {
     }
     // Average -- divide by how many
     if (count > 0) {
-      sum.div(count);
-      // Our desired vector is the average scaled to maximum speed
-      sum.normalize();
-      sum.mult(maxspeed);
+      // Our desired vector is moving away maximum speed
+      sum.setMag(maxspeed);
       // Implement Reynolds: Steering = Desired - Velocity
       PVector steer = PVector.sub(sum, velocity);
       steer.limit(maxforce);
diff --git a/introduction/Exercise_I_3_Walker_To_Mouse/Exercise_I_3_Walker_To_Mouse.pde b/introduction/Exercise_I_3_Walker_To_Mouse/Exercise_I_3_Walker_To_Mouse.pde
new file mode 100644
index 00000000..eccfde15
--- /dev/null
+++ b/introduction/Exercise_I_3_Walker_To_Mouse/Exercise_I_3_Walker_To_Mouse.pde
@@ -0,0 +1,20 @@
+// The Nature of Code
+// Daniel Shiffman
+// http://natureofcode.com
+
+Walker w;
+
+void setup() {
+  size(640,360);
+  // Create a walker object
+  w = new Walker();
+  background(255);
+}
+
+void draw() {
+  // Run the walker object
+  w.step();
+  w.render();
+}
+
+
diff --git a/introduction/Exercise_I_3_Walker_To_Mouse/Walker.pde b/introduction/Exercise_I_3_Walker_To_Mouse/Walker.pde
new file mode 100644
index 00000000..cf71ab06
--- /dev/null
+++ b/introduction/Exercise_I_3_Walker_To_Mouse/Walker.pde
@@ -0,0 +1,49 @@
+// The Nature of Code
+// Daniel Shiffman
+// http://natureofcode.com
+
+// A random walker object!
+
+class Walker {
+  int x, y;
+
+  Walker() {
+    x = width/2;
+    y = height/2;
+  }
+
+  void render() {
+    stroke(0);
+    strokeWeight(2);
+    point(x, y);
+  }
+
+  // Randomly move up, down, left, right, or stay in one place
+  void step() {
+
+    float r = random(1);
+    // A 50% of moving towards the mouse
+    if (r < 0.5) {    
+      int xdir = (mouseX-x);
+      int ydir = (mouseY-y);
+      if (xdir != 0) {
+        xdir /= abs(xdir);
+      } 
+      if (ydir != 0) {
+        ydir /= abs(ydir);
+      }
+      x += xdir;
+      y += ydir;
+    } else {
+      int xdir = int(random(-2, 2));
+      int ydir = int(random(-2, 2));
+      println(xdir);
+      x += xdir;
+      y += ydir;
+    }
+
+    x = constrain(x, 0, width-1);
+    y = constrain(y, 0, height-1);
+  }
+}
+