// Welcome back to CS00b!

// Please share webcams and open VM: www.ktbyte.com/vm

// Please open project from last week!

// GLOBAL VARIABLES
boolean firing = false;
float x;
float y;

float xSpeed;
float ySpeed;

float lastX = -100;  // where did last cannonball land

PImage bombImg;

void setup() {
  size(600, 400);

  bombImg = loadImage("http://findicons.com/files/icons/1332/danger_mouse/256/bomb.png");
}

void draw() {
  background(128, 196, 255);

  fill(0, 128, 0);
  noStroke();  // removes borders
  rect(0, 300, width, 200);
  // 4 inputs: x, y (UL corner), width, height

  stroke(255, 0, 0);  // red
  strokeWeight(9);    // thick line
//  line(lastX - 15, 300 - 15, lastX + 15, 300 + 15);
//  line(lastX + 15, 300 - 15, lastX - 15, 300 + 15);
  fill(255, 0, 0);
  textAlign(CENTER, CENTER);
  textSize(48);
  text("X", lastX, 300);

  drawTrajectory();

  if (firing) {
    // draw cannonball
    noStroke();
    fill(0);  // black
    // ellipse(x, y, 30, 30);
    //imageMode(CENTER);
    drawImage(bombImg, x, y, frameCount*-4, 64, 64);

    x += xSpeed;
    y += ySpeed;

    ySpeed += 0.05;

    if (y > 300) {
      firing = false;
      lastX = x;
    }
  }
}

void mousePressed() {
  // only fire again if not already firing
  if (!firing) {
    firing = true;
    // cannon speed is proportional to distance to center
    //   at ground level
    xSpeed = mouseX - width / 2;
    ySpeed = mouseY - 300;
    float power = dist(mouseX, mouseY, width/2, 300);
    xSpeed /= 50;
    ySpeed /= 50;
    // scales up to power level 5, scales down from original
    //   power level

    x = width / 2;
    y = 300;
  }
}

// i want a function that draws an arc for the cannonball's trajectory
void drawTrajectory() {
  // when you create local variables the same name as global, they
  //   "shadow" the global variables - Java will assume you're talking
  //   about the local variables not the globals w/in this functions
  float x = width / 2;
  float y = 300;

  float xSpeed = mouseX - width / 2;
  float ySpeed = mouseY - 300;
  float power = dist(mouseX, mouseY, width/2, 300);
  xSpeed /= 50;
  ySpeed /= 50;

  // we want to loop through all different cannonball positions
  //   that we'd see if we fired the cannonball, until that position
  //   would hit the ground
  while (y <= 300) {
    float nextX = x + xSpeed;  // position
    float nextY = y + ySpeed;

    stroke(128);  // gray
    strokeWeight(1);
    line(x, y, nextX, nextY);

    x = nextX;
    y = nextY;

    ySpeed += 0.05;  // change in position
  }

  // we know once the loop is over, the ball would have hit the ground
  noStroke();
  fill(0, 0, 0, 100);  // 100/255 opacity means it'll be faded
  ellipse(x, 300, 30, 30);
}

// need a function that draws any image at any position & angle & dimensions
void drawImage(PImage img, float x, float y, float angle, int w, int h) {
  translate(x, y);
  rotate(radians(angle));  // can convert input degrees to radians
  imageMode(CENTER);
  image(img, 0, 0, w, h);
}


// gives the angle in degrees for direction the "cannon" is facing
float firingDirection() {
  return degrees(atan2(width / 2 - mouseX, 300 - mouseY));
  //                   arctangent finds angle based on distances
}

// homework: draw a cannon using the drawImage and firingDirection funcs
//   replace or add one more image (rotated) to the program - be creative