a port of the Processing Visualization Language

### Reach3

Based on code from Keith Peters (www.bit-101.com) The arm follows the position of the ball by calculating the angles with atan2().

```// All Examples Written by Casey Reas and Ben Fry

// unless otherwise stated.

int numSegments = 6;

float[] x = new float[numSegments];

float[] y = new float[numSegments];

float[] angle = new float[numSegments];

float segLength = 15;

float targetX, targetY;

float ballX = 50;

float ballY = 50;

int ballXDirection = 1;

int ballYDirection = -1;

void setup() {

size(200, 200);

smooth();

strokeWeight(20.0);

stroke(0, 100);

noFill();

x[x.length-1] = width/2;     // Set base x-coordinate

y[x.length-1] = height;  // Set base y-coordinate

}

void draw() {

background(226);

strokeWeight(20);

ballX = ballX + 1.0 * ballXDirection;

ballY = ballY + 0.8 * ballYDirection;

if(ballX > width-25 || ballX < 25) {

ballXDirection *= -1;

}

if(ballY > height-25 || ballY < 25) {

ballYDirection *= -1;

}

ellipse(ballX, ballY, 30, 30);

reachSegment(0, ballX, ballY);

for(int i=1; i<numSegments; i++) {

reachSegment(i, targetX, targetY);

}

for(int i=x.length-1; i>=1; i--) {

positionSegment(i, i-1);

}

for(int i=0; i<x.length; i++) {

segment(x[i], y[i], angle[i], (i+1)*2);

}

}

void positionSegment(int a, int b) {

x[b] = x[a] + cos(angle[a]) * segLength;

y[b] = y[a] + sin(angle[a]) * segLength;

}

void reachSegment(int i, float xin, float yin) {

float dx = xin - x[i];

float dy = yin - y[i];

angle[i] = atan2(dy, dx);

targetX = xin - cos(angle[i]) * segLength;

targetY = yin - sin(angle[i]) * segLength;

}

void segment(float x, float y, float a, float sw) {

strokeWeight(sw);

pushMatrix();

translate(x, y);

rotate(a);

line(0, 0, segLength, 0);

popMatrix();

}```