This example is for Processing 3+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.

**Follow 2** based on code from Keith Peters.

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().

float[] x = new float[2]; float[] y = new float[2]; float segLength = 50; void setup() { size(640, 360); strokeWeight(20.0); stroke(255, 100); } void draw() { background(0); 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(); }