angled_delta.pde

Eye e1;

void setup() {
  size(640, 360);
  noStroke();
  e1 = new Eye(640/2, 360/2, 64);
}

void draw() {
  background(102);
  
  e1.update(mouseX, mouseY);
  e1.display();
}

class Eye {
  int x, y;
  int size;
  
  float angle = 0.0;
  float mouse_angle = 0.0;
  float px = 0.0;
  float pz = 0.0;
  float delta = 0.0;
  
  Eye(int tx, int ty, int ts) {
    x = tx;
    y = ty;
    size = ts;
 }

  void update(int mx, int my) {
    float ex = 0;
    float ez = 0;
    px = -(my-y);
    pz = (mx-x);
    
    float vx = px - ex;
    float vz = pz - ez;
    mouse_angle = atan2(-vz, vx) / (PI / 180.0);
    
    delta = (mouse_angle - angle) % 360.0;
    if      (delta >  180.0) delta -= 360;
    else if (delta < -180.0) delta += 360;
    
    float v = 5.0;
    float mover = delta > v ? v : delta < -v ? -v : delta;
    if (mousePressed) angle += mover;
  }
  
  void display() {
    pushMatrix();
    translate(x, y);
    fill(255);
    ellipse(0, 0, size, size);
    rotate(-((angle+90) / 180 * PI));
    fill(153, 204, 0);
    ellipse(size/4, 0, size/2, size/2);
    popMatrix();
    
    fill(255);
    //text(String.format("cur angle: %.2f", angle), 8, 16);
    //text(String.format("mouse angle: %.2f", mouse_angle), 8, 32);
    //text(String.format("delta angle: %.2f", delta), 8, 48);
    //text(String.format("mouse pos x,z: %.0f, %.0f", px, pz), 8, 64);
  }
}