topical media & game development
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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graphic-processing-site-examples-Topics-Interaction-Follow2-Follow2.pde / pde
Follow 2. 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(). 

  
  
  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();
  }
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 20/2/2008

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