a port of the Processing Visualization Language

Follow2

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().

Original Processing.org Example: Follow2

// All Examples Written by Casey Reas and Ben Fry

// unless otherwise stated.

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();

}
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