Lecture 08

Arrays.

---

A case where the arrays are set with specific values at the start:

 
float xPoints[] = {
  280.0, 289.0, 134.0, 64.0, 151.0
};
float yPoints[] = {
  74.0, 205.0, 260.0, 194.0, 61.0
};

void setup() {
  size (400, 400);
  smooth();
}

void draw() {
  background(126);
  beginShape();
  for (int i=0; i<5; i++) {
    float px = xPoints[i] + 30*noise(i + millis()/200.0);
    float py = yPoints[i] + 30*noise(i + millis()/313.0);
    vertex(px,py);

  }
  endShape(CLOSE);
}

---

“Flocking” simulation — actually, 100 drunks:

float   pxArray[]; // declaration
float[] pyArray;
int nDrunks = 100;

void setup() {
  size(400, 400);

  pxArray = new float[nDrunks]; // ALLOCATION
  pyArray = new float[nDrunks];

  for (int i=0; i < ndrunks ; i++) {
    pxArray[i] = width/2; // assignment
    pyArray[i] = height/2;
  }
}

void updateFlockingSimulation() {
  for (int i=0; i < nDrunks; i++) {
    pxArray[i] += random(-4, 4);
    pyArray[i] += random(-4, 4);
  }
}

void renderFlockingSimulation() {
  for (int i=0; i < nDrunks; i++) {
    ellipse(pxArray[i], pyArray[i], 20, 20);
  }
}

void draw() {
  background(128);
  updateFlockingSimulation();
  renderFlockingSimulation();
}

---

A Point Recorder:

ArrayList xPoints;
ArrayList yPoints;

void setup() {
  size(400, 400);
  xPoints = new ArrayList();
  yPoints = new ArrayList();
}

void draw() {
  background(200);
  noFill();

  int n = xPoints.size();
  beginShape();
  for (int i=0; i < n ; i++) {
    float px = ((Float)(xPoints.get(i)));
    float py = ((Float)(yPoints.get(i)));
    vertex(px, py);
  }
  endShape();
}

void mousePressed() {
  xPoints.add((float)mouseX);
  yPoints.add((float)mouseY);
}

void keyPressed() {
  print("float xPoints[] = {");
  int nx = xPoints.size();
  for (int i=0; i < nx; i++) {
    float px = ((Float)(xPoints.get(i)));
    if (i != (nx-1)) {
      print (px + ", ");
    } else {
      print (px);
    }
  }
  println("};");

  print("float yPoints[] = {");
  int ny = yPoints.size();
  for (int i=0; i < ny; i++) {
    float py = ((Float)(yPoints.get(i)));
    if (i != (ny-1)) {
      print (py + ", ");
    } else {
      print (py);
    }
  }
  println("};");
}

---

More on Transforms.

A Rotating Square: Two ways, different advantages.

int drawState = 0;
void setup() {
  size (300, 300);
  smooth();
}

void keyPressed() {
  drawState = (drawState+1)%3;
}

//=========================================================
void draw() {

  fill(255);
  text("Draw State = " + drawState, 15, 20); 

  switch (drawState) {
  case 0:
    draw0();
    break;
  case 1: 
    draw1();
    break;
  case 2: 
    draw2();
    break;
  }

  fill(100, 64); 
  rect(0, 0, width, height);
}

//=========================================================
void draw0() {
  // Use rotate and translate to compute the vertices for us.
  pushMatrix();
  translate(width/2, height/2); 
  rotate (millis()/400.0);
  rect (-50, -50, 100, 100); 
  popMatrix();
}

//=========================================================
void draw1() {
  // Compute the vertices mathematically, ourselves. 
  float cx = width/2;
  float cy = height/2;
  float T = millis()/400.0 - QUARTER_PI;
  float r = 50.0 * sqrt(2.0); 

  beginShape();
  vertex(cx + r*cos(T          ), cy + r*sin(T          ));
  vertex(cx + r*cos(T+HALF_PI*1), cy + r*sin(T+HALF_PI*1));
  vertex(cx + r*cos(T+HALF_PI*2), cy + r*sin(T+HALF_PI*2));
  vertex(cx + r*cos(T+HALF_PI*3), cy + r*sin(T+HALF_PI*3));
  endShape(CLOSE);
}

//=========================================================
void draw2() {
  // Compute the vertices mathematically, ourselves. 
  float cx = width/2;
  float cy = height/2;
  float T = millis()/400.0 - QUARTER_PI;
  float r = 50.0 * sqrt(2.0); 

  float dx = 15*sin(millis()/50.0);
  float dy = 15*cos(millis()/50.0);
  float dT = 0.4 * sin(millis()/80.0);

  beginShape();
  vertex(cx + r*cos(T+dT       ), cy + r*sin(T+dT       ));
  vertex(cx + r*cos(T+HALF_PI*1), cy + r*sin(T+HALF_PI*1));
  vertex(cx + r*cos(T+HALF_PI*2) + dx, cy + r*sin(T+HALF_PI*2) + dy);
  vertex(cx + r*cos(T+HALF_PI*3), cy + r*sin(T+HALF_PI*3));
  endShape(CLOSE);
}

Limbs: Here’s an Arm

void setup() {
  size(500, 500);
}

void draw() {
  background(100); 
  fill(255,255,255, 128); 
  smooth();

  pushMatrix();

  translate(150, 150);
  ellipse(0,0, 10,10);
  rect(0,0, 100, 100); 

  translate(75,75); 
  ellipse(0,0, 10,10);
  rect(0,0, 50,150); 

  translate(25,125); 
  ellipse(0,0, 10,10);
  rect(0,0, 50,50);

  popMatrix();
}

Limbs: Here’s an Arm, Moving

void setup() {
  size(500, 500);
}

void draw() {
  background(100); 
  fill(255,255,255, 128); 
  smooth();

  float ang1 =  0.5 * (sin(millis()/2000.0));
  float ang2 =  0.7 * (sin(millis()/1111.0));
  float ang3 =  1.2 * (sin(millis()/ 313.0));

  pushMatrix();

  translate(150, 150);
  rotate( ang1 );
  ellipse(0,0, 10,10);
  rect(0,0, 100, 100); 

  translate(75,75); 
  rotate( ang2 );
  ellipse(0,0, 10,10);
  rect(0,0, 50,150); 

  translate(25,125); 
  rotate( ang3 );
  ellipse(0,0, 10,10);
  rect(0,0, 50,50);

  popMatrix();
}

Noisy Limb:

void setup() {
  size(500, 500);
}

void draw() {
  background(100); 
  fill(255,255,255, 128); 
  smooth();

  float ang1 =  0.5 * (noise(millis()/2000.0) - 0.5);
  float ang2 =  0.7 * (noise(millis()/1111.0) - 0.5);
  float ang3 =  1.2 * (noise(millis()/ 313.0) - 0.5);

  pushMatrix();

  translate(150, 150);
  rotate( ang1 );
  ellipse(0,0, 10,10);
  rect(0,0, 100, 100); 

  translate(75,75); 
  rotate( ang2 );
  ellipse(0,0, 10,10);
  rect(0,0, 50,150); 

  translate(25,125); 
  rotate( ang3 );
  ellipse(0,0, 10,10);
  rect(0,0, 50,50);

  popMatrix();
}