IFD:PhysicalComp2011: Difference between revisions

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Frederic Gmeiner

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 * [http://processing.org/reference/mouseY.html mouseY]
 * [http://processing.org/reference/random_.html random()]
+== 07.11.2011 Processing sketches ==
+=== Exercise I: Bouncing Line (Advanced)===
+<source lang="java">
+/* BOUNCING LINE ADVANCED
+ *
+ * Notice the introduction of the variables
+ * "speed" and "direction to control the speed
+ * and direction of the moving line inependently.
+ *
+ * Frederic Gmeiner 2011
+ */
+// variable to hold the currect x position of the line
+float lineX = 0;
+// variable that controls the speed
+float speed = 2.3f;
+// variable that controls the direction
+// (either 1 or -1)
+int direction = 1;
+void setup(){
+  size(300,300);
+}
+void draw(){
+  background(204);
+   // if the x position of the line exceeds the right border of the window
+   // OR (||) the x position of the line exceeds the left border
+   // of the window:
+  if(lineX > width || lineX < 0){
+    direction = direction * -1; // change the direction
+  }
+  // here the new x-position is calculated by adding the speed and direction onto the
+  // current x-position. if direction is -1, lineX decreases. if direction is 1, lineX
+  // increases:
+  lineX = lineX + (speed * direction);
+  // draw the line based on the calculated x-position:
+  line(lineX,0,lineX,height);
+}
+</source>
+<br /><br />
+=== Exercise II: Solution===
+<source lang="java">
+/* A FRIGHTENED SQUARE
+ *
+ * A little sketch to illustrate the random() function
+ * and a more complex boolean equation to check whether
+ * the mouse pointer is inside a rectangular shape.
+ *
+ * Frederic Gmeiner 2011
+ */
+// the x an y positions of the square:
+float xPos = 200f;
+float yPos = 200f;
+// the width and height of the square:
+int s = 20;
+void setup(){
+   size(400,400);
+}
+void draw(){
+  background(204);
+  // Here we check if the position of the mouse is somewhere inside of the
+  // square. To know this, all these four contitions must be true ( && ):
+  if( mouseX > xPos && mouseX < xPos + s && mouseY > yPos && mouseY < yPos + s){
+      xPos += random(-2,3); // add a random value between -2 and 3 to the xPos
+      yPos += random(-2,3);
+      fill(40);
+  }else{
+    fill(255);
+  }
+  // finally draw the square:
+  rect(xPos, yPos, s, s);
+}
+</source>
+<br /><br />
+=== V for() loops===
+<source lang="java">
+/* DYNAMIC DISTRIBUTION
+ *
+ * This sketch demonstrates the usage of
+ * a for-loop for calculating and drawing
+ * a certain number of ellipses according
+ * to the changing mouseX position.
+ *
+ * Frederic Gmeiner 2011
+ */
+// the number of circles:
+int numCircles = 15;
+void setup(){
+  size(500,200);
+  stroke(255);
+  fill(150);
+  smooth();
+}
+void draw(){
+  background(255);
+  // calculate the distance between the circles
+  // so that in total it results in the mouseX position:
+  float distance = mouseX / (numCircles-1);
+  // for every circle (numCircles) calculate the xPos
+  // and draw it onto the screen:
+  for(int i=0; i < numCircles; i++){
+    float xPos = i*distance;
+    ellipse(xPos,100,10,10);
+  }
+}
+</source>
+<br /><br />
+=== VI The array: a collection of variables===
+<source lang="java">
+/* Random points in an array
+ *
+ * This demonstrates how to store values in
+ * an array. This is useful when working with
+ * many things which share the same parameters.
+ * Here we use two arrays to store the coordinates
+ * of circles.
+ *
+ * Frederic Gmeiner 2011
+ */
+// total number of circles:
+int numCircles = 40;
+// the radius of the circles
+float rad = 20f;
+// initializing two arrays for storing the x and y positions
+// of the circles:
+float[] xPositions = new float[numCircles];
+float[] yPositions = new float[numCircles];
+void setup(){
+  size(500,500);
+  smooth();
+  noStroke();
+  fill(150);
+  // iterating over the arrays to set each position with
+  // a random value based on the screen size:
+  for(int i=0; i< numCircles; i++){
+    xPositions[i] = random(0,width);
+    yPositions[i] = random(0,height);
+  }
+}
+void draw(){
+  background(204);
+  // again iterating over the arrays. but this time we only
+  // get the x and y coordinates to draw the circles:
+  for(int i=0; i< numCircles; i++){
+    ellipse(xPositions[i], yPositions[i], rad, rad);
+  }
+}
+</source>
+<br /><br />
 [[Category:WS11]]