#javascript-processing-example-topic-interaction-follow3.htm / htm
<!DOCTYPE html> <html><head> <script src="javascript-processing-example-processing.js"></script> <script src="javascript-processing-example-init.js"></script> <link rel="stylesheet" href="javascript-processing-example-style.css"> </head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1> <h2>Follow3</h2> <p>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().</p> <p><a href="http://processing.org/learning/topics/follow3.html"><b>Original Processing.org Example:</b> Follow3</a><br> <script type="application/processing"> 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(); } </script><canvas width="200" height="200"></canvas></p> <div style="overflow: hidden; height: 0px; width: 0px;"></div> <pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a> // unless otherwise stated.</b> 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(); }</pre> </body></html>
(C) Æliens 20/2/2008
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