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().

Original Processing.org Example: Reach3

// 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();

}
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