IFD:PhysicalComp2011: Difference between revisions

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 == 14.11.2011 Processing sketches ==
+=== EXERCISE III: SOLUTION ===
+<source lang="java">
+/* PULSING CIRCLES
+ *
+ * Mofification of the example above so that
+ * the circles will shrink and grow by using
+ * a sinewave.
+ *
+ * Frederic Gmeiner 2011
+ */
+int numCircles = 40;
+float rad = 20f;
+// initial angle of 0. this will increase during the
+// runtime of the programm and will be used to calculate
+// the sine based on this value in order so modify the size of
+// circles.
+float angle = 0.0f;
+// how fast the angle will increase is defined by the speed variable:
+float speed = 0.01;
+float[] xPositions = new float[numCircles];
+float[] yPositions = new float[numCircles];
+void setup(){
+  size(500,500);
+  smooth();
+  noStroke();
+  fill(150);
+  for(int i=0; i< numCircles; i++){
+    xPositions[i] = random(0,width);
+    yPositions[i] = random(0,height);
+  }
+}
+void draw(){
+  background(204);
+  // add the speed value to the angle:
+  angle += speed;
+  // calculate the diamater by calculating the sine value of the
+  // angle and scaling it up by the value of 30. This is necessary since
+  // the sin() funtion returns only values between -1 and 1.
+  float diameter = sin(angle)*30;
+  for(int i=0; i< numCircles; i++){
+    // draw the circles:
+    ellipse(xPositions[i], yPositions[i], diameter, diameter);
+  }
+}
+</source>
+<br /><br />
+=== VII.a Another sine and cosine example ===
+<source lang="java">
+/* ELLIPTICAL MOTION
+ *
+ * A little demonstration of the sine and
+ * cosine relation.
+ *
+ * Frederic Gmeiner 2011
+ */
+float speed = 0.1f;  // frequency
+float angle = 0.0f; // you might also call it theta
+void draw(){
+  background(200);
+  angle += speed;
+  point(50,50);
+  point(50+ (cos(angle)/2*50), 50+ (sin(angle)*50));
+}
+</source>
+<br /><br />
+=== VII.b Relation of degrees, PI and sine ===
+<source lang="java">
+int degr= 0;
+println("0° Degrees:");
+println("PI:" + radians(degr) / PI);
+println("sine:" + round(sin(radians(degr))) + "\n");
+degr= 90;
+println("90° Degrees:");
+println("PI:" + radians(degr) / PI);
+println("sine:" + round(sin(radians(degr))) + "\n");
+degr= 180;
+println("180° Degrees:");
+println("PI:" + radians(degr) / PI);
+println("sine:" + round(sin(radians(degr))) + "\n");
+degr= 270;
+println("270° Degrees:");
+println("PI:" + radians(degr) / PI);
+println("sine:" + round(sin(radians(degr))) + "\n");
+degr= 360;
+println("360° Degrees:");
+println("PI:" + radians(degr) / PI);
+println("sine:" + round(sin(radians(degr))) + "\n");
+</source>
+<br /><br />
 === READING DATA FROM A TEXTFILE ===