From 7cde928f9bb806e35c64d70dfedd2043290aa107 Mon Sep 17 00:00:00 2001
From: Daniel Shiffman <daniel@shiffman.net>
Date: Sat, 16 Mar 2013 22:09:18 -0400
Subject: [PATCH] reworked Reflection2 to use PVector and OOP

---
 .../Topics/Motion/Reflection2/Orb.pde         | 80 +++++++++++++++++--
 .../Topics/Motion/Reflection2/Reflection2.pde | 79 +++---------------
 2 files changed, 83 insertions(+), 76 deletions(-)

diff --git a/java/examples/Topics/Motion/Reflection2/Orb.pde b/java/examples/Topics/Motion/Reflection2/Orb.pde
index 7af7ed91b..ab033a911 100644
--- a/java/examples/Topics/Motion/Reflection2/Orb.pde
+++ b/java/examples/Topics/Motion/Reflection2/Orb.pde
@@ -1,14 +1,78 @@
-class Orb{
-  float x, y, r;
+class Orb {
+  PVector position;
+  PVector velocity;
+  float r;
+  float damping = 0.8;
 
-  // Default constructor
-  Orb() {
+  Orb(float x, float y, float r_) {
+    position = new PVector(x, y);
+    velocity = new PVector(.5, 0);
+    r = r_;
   }
 
-  Orb(float x, float y, float r) {
-    this.x = x;
-    this.y = y;
-    this.r = r;
+  void move() {
+    // Move orb
+    velocity.add(gravity);
+    position.add(velocity);
+  }
+
+  void display() {
+    // Draw orb
+    noStroke();
+    fill(200);
+    ellipse(position.x, position.y, r*2, r*2);
+  }
+
+  void checkWallCollision() {
+    if (position.x > width-r) {
+      position.x = width-r;
+      velocity.x *= -1;
+      velocity.x *= damping;
+    } 
+    else if (position.x < r) {
+      position.x = r;
+      velocity.x *= -1;
+      velocity.x *= damping;
+    }
+  }
+
+  void checkGroundCollision(Ground groundSegment) {
+
+    // Get difference between orb and ground
+    float deltaX = position.x - groundSegment.x;
+    float deltaY = position.y - groundSegment.y;
+
+    // Precalculate trig values
+    float cosine = cos(groundSegment.rot);
+    float sine = sin(groundSegment.rot);
+
+    /* Rotate ground and velocity to allow 
+     orthogonal collision calculations */
+    float groundXTemp = cosine * deltaX + sine * deltaY;
+    float groundYTemp = cosine * deltaY - sine * deltaX;
+    float velocityXTemp = cosine * velocity.x + sine * velocity.y;
+    float velocityYTemp = cosine * velocity.y - sine * velocity.x;
+
+    /* Ground collision - check for surface 
+     collision and also that orb is within 
+     left/rights bounds of ground segment */
+    if (groundYTemp > -r &&
+      position.x > groundSegment.x1 &&
+      position.x < groundSegment.x2 ) {
+      // keep orb from going into ground
+      groundYTemp = -r;
+      // bounce and slow down orb
+      velocityYTemp *= -1.0;
+      velocityYTemp *= damping;
+    }
+
+    // Reset ground, velocity and orb
+    deltaX = cosine * groundXTemp - sine * groundYTemp;
+    deltaY = cosine * groundYTemp + sine * groundXTemp;
+    velocity.x = cosine * velocityXTemp - sine * velocityYTemp;
+    velocity.y = cosine * velocityYTemp + sine * velocityXTemp;
+    position.x = groundSegment.x + deltaX;
+    position.y = groundSegment.y + deltaY;
   }
 }
 
diff --git a/java/examples/Topics/Motion/Reflection2/Reflection2.pde b/java/examples/Topics/Motion/Reflection2/Reflection2.pde
index dd82fa01a..e1967fe8d 100644
--- a/java/examples/Topics/Motion/Reflection2/Reflection2.pde
+++ b/java/examples/Topics/Motion/Reflection2/Reflection2.pde
@@ -7,8 +7,8 @@
  */
 
 Orb orb;
-PVector velocity;
-float gravity = .05, damping = 0.8;
+
+PVector gravity = new PVector(0,0.05);
 int segments = 40;
 Ground[] ground = new Ground[segments];
 float[] peakHeights = new float[segments+1];
@@ -16,7 +16,7 @@ float[] peakHeights = new float[segments+1];
 void setup(){
   size(640, 360);
   orb = new Orb(50, 50, 3);
-  velocity = new PVector(.5, 0);
+
 
   // Calculate ground peak heights 
   for (int i=0; i<peakHeights.length; i++){
@@ -39,12 +39,11 @@ void draw(){
   noStroke();
   fill(0, 15);
   rect(0, 0, width, height);
-
-  // Move orb
-  orb.x += velocity.x;
-  velocity.y += gravity;
-  orb.y += velocity.y;
-
+  
+  orb.move();
+  orb.display();
+  orb.checkWallCollision();
+  
   // Draw ground
   fill(127);
   beginShape();
@@ -56,71 +55,15 @@ void draw(){
   vertex(ground[0].x1, height);
   endShape(CLOSE);
 
-  // Draw orb
-  noStroke();
-  fill(200);
-  ellipse(orb.x, orb.y, orb.r*2, orb.r*2);
 
-  // Collision detection
-  checkWallCollision();
   for (int i=0; i<segments; i++){
-    checkGroundCollision(ground[i]);
+    orb.checkGroundCollision(ground[i]);
   }
 }
 
 
-void checkWallCollision(){
-  if (orb.x > width-orb.r){
-    orb.x = width-orb.r;
-    velocity.x *= -1;
-    velocity.x *= damping;
-  } 
-  else if (orb.x < orb.r){
-    orb.x = orb.r;
-    velocity.x *= -1;
-    velocity.x *= damping;
-  }
-}
-
-
-void checkGroundCollision(Ground groundSegment) {
-
-  // Get difference between orb and ground
-  float deltaX = orb.x - groundSegment.x;
-  float deltaY = orb.y - groundSegment.y;
-
-  // Precalculate trig values
-  float cosine = cos(groundSegment.rot);
-  float sine = sin(groundSegment.rot);
-
-  /* Rotate ground and velocity to allow 
-   orthogonal collision calculations */
-  float groundXTemp = cosine * deltaX + sine * deltaY;
-  float groundYTemp = cosine * deltaY - sine * deltaX;
-  float velocityXTemp = cosine * velocity.x + sine * velocity.y;
-  float velocityYTemp = cosine * velocity.y - sine * velocity.x;
-
-  /* Ground collision - check for surface 
-   collision and also that orb is within 
-   left/rights bounds of ground segment */
-  if (groundYTemp > -orb.r &&
-    orb.x > groundSegment.x1 &&
-    orb.x < groundSegment.x2 ){
-    // keep orb from going into ground
-    groundYTemp = -orb.r;
-    // bounce and slow down orb
-    velocityYTemp *= -1.0;
-    velocityYTemp *= damping;
-  }
-
-  // Reset ground, velocity and orb
-  deltaX = cosine * groundXTemp - sine * groundYTemp;
-  deltaY = cosine * groundYTemp + sine * groundXTemp;
-  velocity.x = cosine * velocityXTemp - sine * velocityYTemp;
-  velocity.y = cosine * velocityYTemp + sine * velocityXTemp;
-  orb.x = groundSegment.x + deltaX;
-  orb.y = groundSegment.y + deltaY;
-}
+
+