Re-adding Topics to SVN

java/examples/Topics/Interaction/Follow1/Follow1.pde

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+/**
+ * Follow 1. 
+ * Based on code from Keith Peters (www.bit-101.com). 
+ * 
+ * A line segment is pushed and pulled by the cursor.
+ */
+
+float x = 100;
+float y = 100;
+float angle1 = 0.0;
+float segLength = 50;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0);
+  stroke(0, 100);
+}
+
+void draw() {
+  background(226);
+  
+  float dx = mouseX - x;
+  float dy = mouseY - y;
+  angle1 = atan2(dy, dx);  
+  x = mouseX - (cos(angle1) * segLength);
+  y = mouseY - (sin(angle1) * segLength);
+ 
+  segment(x, y, angle1); 
+  ellipse(x, y, 20, 20);
+}
+
+void segment(float x, float y, float a) {
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}

java/examples/Topics/Interaction/Follow2/Follow2.pde

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+/**
+ * Follow 2. 
+ * Based on code from Keith Peters (www.bit-101.com). 
+ * 
+ * A two-segmented arm follows the cursor position. The relative
+ * angle between the segments is calculated with atan2() and the
+ * position calculated with sin() and cos().
+ */
+
+float[] x = new float[2];
+float[] y = new float[2];
+float segLength = 50;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0);
+  stroke(0, 100);
+}
+
+void draw() {
+  background(226);
+  dragSegment(0, mouseX, mouseY);
+  dragSegment(1, x[0], y[0]);
+}
+
+void dragSegment(int i, float xin, float yin) {
+  float dx = xin - x[i];
+  float dy = yin - y[i];
+  float angle = atan2(dy, dx);  
+  x[i] = xin - cos(angle) * segLength;
+  y[i] = yin - sin(angle) * segLength;
+  segment(x[i], y[i], angle);
+}
+
+void segment(float x, float y, float a) {
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}

java/examples/Topics/Interaction/Follow3/Follow3.pde

@@ -0,0 +1,44 @@
+/**
+ * Follow 3. 
+ * Based on code from Keith Peters (www.bit-101.com). 
+ * 
+ * A segmented line follows the mouse. The relative angle from
+ * each segment to the next is calculated with atan2() and the
+ * position of the next is calculated with sin() and cos().
+ */
+
+float[] x = new float[20];
+float[] y = new float[20];
+float segLength = 9;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(5);
+  stroke(0, 100);
+}
+
+void draw() {
+  background(226);
+  dragSegment(0, mouseX, mouseY);
+  for(int i=0; i<x.length-1; i++) {
+    dragSegment(i+1, x[i], y[i]);
+  }
+}
+
+void dragSegment(int i, float xin, float yin) {
+  float dx = xin - x[i];
+  float dy = yin - y[i];
+  float angle = atan2(dy, dx);  
+  x[i] = xin - cos(angle) * segLength;
+  y[i] = yin - sin(angle) * segLength;
+  segment(x[i], y[i], angle);
+}
+
+void segment(float x, float y, float a) {
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}

java/examples/Topics/Interaction/Reach1/Reach1.pde

@@ -0,0 +1,49 @@
+/**
+ * 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;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0);
+  stroke(0, 100);
+}
+
+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); 
+}
+
+void segment(float x, float y, float a) {
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}
+

java/examples/Topics/Interaction/Reach2/Reach2.pde

@@ -0,0 +1,60 @@
+/**
+ * Reach 2. 
+ * Based on code from Keith Peters (www.bit-101.com)
+ * 
+ * The arm follows the position of the mouse by
+ * calculating the angles with atan2(). 
+ */
+
+int numSegments = 10;
+float[] x = new float[numSegments];
+float[] y = new float[numSegments];
+float[] angle = new float[numSegments];
+float segLength = 20;
+float targetX, targetY;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0);
+  stroke(0, 100);
+  x[x.length-1] = 0;     // Set base x-coordinate
+  y[x.length-1] = height;  // Set base y-coordinate
+}
+
+void draw() {
+  background(226);
+  
+  reachSegment(0, mouseX, mouseY);
+  for(int i=1; i<numSegments; i++) {
+    reachSegment(i, targetX, targetY);
+  }
+  for(int i=x.length-1; i>=1; i--) {
+    positionSegment(i, i-1);  
+  } 
+  for(int i=0; i<x.length; i++) {
+    segment(x[i], y[i], angle[i], (i+1)*2); 
+  }
+}
+
+void positionSegment(int a, int b) {
+  x[b] = x[a] + cos(angle[a]) * segLength;
+  y[b] = y[a] + sin(angle[a]) * segLength; 
+}
+
+void reachSegment(int i, float xin, float yin) {
+  float dx = xin - x[i];
+  float dy = yin - y[i];
+  angle[i] = atan2(dy, dx);  
+  targetX = xin - cos(angle[i]) * segLength;
+  targetY = yin - sin(angle[i]) * segLength;
+}
+
+void segment(float x, float y, float a, float sw) {
+  strokeWeight(sw);
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}

java/examples/Topics/Interaction/Reach3/Reach3.pde

@@ -0,0 +1,77 @@
+/**
+ * Reach 3. 
+ * Based on code from Keith Peters (www.bit-101.com)
+ * 
+ * The arm follows the position of the ball by
+ * calculating the angles with atan2().
+ */
+
+int numSegments = 6;
+float[] x = new float[numSegments];
+float[] y = new float[numSegments];
+float[] angle = new float[numSegments];
+float segLength = 15;
+float targetX, targetY;
+
+float ballX = 50;
+float ballY = 50;
+int ballXDirection = 1;
+int ballYDirection = -1;
+
+void setup() {
+  size(200, 200);
+  smooth(); 
+  strokeWeight(20.0);
+  stroke(0, 100);
+  noFill();
+  x[x.length-1] = width/2;     // Set base x-coordinate
+  y[x.length-1] = height;  // Set base y-coordinate
+}
+
+void draw() {
+  background(226);
+  
+  strokeWeight(20);
+  ballX = ballX + 1.0 * ballXDirection;
+  ballY = ballY + 0.8 * ballYDirection;
+  if(ballX > width-25 || ballX < 25) {
+    ballXDirection *= -1; 
+  }
+  if(ballY > height-25 || ballY < 25) {
+    ballYDirection *= -1; 
+  }
+  ellipse(ballX, ballY, 30, 30);
+  
+  reachSegment(0, ballX, ballY);
+  for(int i=1; i<numSegments; i++) {
+    reachSegment(i, targetX, targetY);
+  }
+  for(int i=x.length-1; i>=1; i--) {
+    positionSegment(i, i-1);  
+  } 
+  for(int i=0; i<x.length; i++) {
+    segment(x[i], y[i], angle[i], (i+1)*2); 
+  }
+}
+
+void positionSegment(int a, int b) {
+  x[b] = x[a] + cos(angle[a]) * segLength;
+  y[b] = y[a] + sin(angle[a]) * segLength; 
+}
+
+void reachSegment(int i, float xin, float yin) {
+  float dx = xin - x[i];
+  float dy = yin - y[i];
+  angle[i] = atan2(dy, dx);  
+  targetX = xin - cos(angle[i]) * segLength;
+  targetY = yin - sin(angle[i]) * segLength;
+}
+
+void segment(float x, float y, float a, float sw) {
+  strokeWeight(sw);
+  pushMatrix();
+  translate(x, y);
+  rotate(a);
+  line(0, 0, segLength, 0);
+  popMatrix();
+}

java/examples/Topics/Interaction/Tickle/Tickle.pde

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+/**
+ * Tickle. 
+ * 
+ * The word "tickle" jitters when the cursor hovers over.
+ * Sometimes, it can be tickled off the screen.
+ */
+
+String message = "tickle";
+float x, y; // X and Y coordinates of text
+float hr, vr;  // horizontal and vertical radius of the text
+
+void setup() {
+  size(200, 200);
+  PFont font = loadFont("AmericanTypewriter-24.vlw");
+  textFont(font);
+  textAlign(CENTER, CENTER);
+  hr = textWidth(message) / 2;
+  vr = (textAscent() + textDescent()) / 2;
+  noStroke();
+  x = width / 2;
+  y = height / 2;
+}
+
+void draw() {
+  // instead of clearing the background, fade it by drawing
+  // a semi-transparent rectangle on top
+  fill(204, 120);
+  rect(0, 0, width, height);
+  fill(0);
+  // If the cursor is over the text, change the position
+  if (abs(mouseX - x) < hr &&
+      abs(mouseY - y) < vr) {
+    x += random(-5, 5);
+    y += random(-5, 5);
+  }
+  text("tickle", x, y);
+}