Limb.

The angle of each segment is controlled with the mouseX and
mouseY position. The transformations applied to the first segment
are also applied to the second segment because they are inside
the same pushMatrix() and popMatrix() group.

Created November 21 2006

 
float x = 50;
float y = 100;
float angle1 = 0.0;
float angle2 = 0.0;
float segLength = 50;

void setup() {
  size(200, 200);
  smooth(); 
  strokeWeight(20.0);
  stroke(0, 100);
}

void draw() {
  background(226);
  
  angle1 = (mouseX/float(width) - 0.5) * -PI;
  angle2 = (mouseY/float(height) - 0.5) * PI;
  
  pushMatrix();
  segment(x, y, angle1); 
  segment(segLength, 0, angle2);
  popMatrix();
}

void segment(float x, float y, float a) {
  translate(x, y);
  rotate(a);
  line(0, 0, segLength, 0);
}