/* @pjs globalKeyEvents="true"; */
/* @pjs pauseOnBlur="true"; */

// Size of the ship
float r = 12;

boolean showarrows = true;

// Draw the ship and other stuff
void display() { 
    translate(0,height);
    scale(1,-1);
//    wrapEdges();
    background(255);
    stroke(0);
    strokeWeight(2);
    fill(0);
    scale(1,-1);
    translate(0,-height);  
    text("Press H to hide the arrows, press U to un-hide",10,10);
    translate(0,height);  
    scale(1,-1);

    image(img,x-15,y,25,25);
    if ( key == 'h') {
    showarrows = false;
    } else if (key == 'u') {
    showarrows = true;
    }
    int tri_width=7;
    if (showarrows) {    
    int x_line=10;
    int y_line=25;
    int line_len=100;
    line(x_line,y_line,x_line,y_line+line_len);
    line(x_line,y_line,x_line+line_len,y_line);
    triangle(x_line-tri_width/2,y_line+line_len,x_line+tri_width/2,y_line+line_len,x_line,y_line+line_len+10);
    triangle(x_line+line_len,y_line-tri_width/2,x_line+line_len,y_line+tri_width/2,x_line+line_len+10,y_line);
    scale(1,-1);
    translate(0,-height);
    text("+x",x_line+line_len+12,height-y_line);
    text("+y",x_line,height-(y_line+line_len+25));
    translate(0,height);
    scale(1,-1);
    }

    // Draw velocity arrow
    float v_scaling=1.0;
    float x_center = x;
    float y_center = y + r; // Make sure the arrow starts from the center of the ship
    stroke(255,0,0); // makes the line red
    strokeWeight(3); // makes the line thicker

    if ( ((vx != 0) || (vy != 0)) && showarrows) {
    line(x_center,y_center,x_center+v_scaling*vx,y_center+v_scaling*vy);
    float vel_angle = -atan2(vy,vx);
    fill(255,0,0); // makes the triangle red
    triangle(x_center+v_scaling*vx+sin(vel_angle)*tri_width/2,y_center+v_scaling*vy+cos(vel_angle)*tri_width/2,x_center+v_scaling*vx-sin(vel_angle)*tri_width/2,y_center+v_scaling*vy-cos(vel_angle)*tri_width/2,x_center+v_scaling*vx+cos(vel_angle)*10,y_center+v_scaling*vy-sin(vel_angle)*10);
    }

    // Draw force arrow
//    float f_scaling=2.25;
    float f_scaling=5.0;
    float Fx = mass*deltaVx/dt;
    float Fy = mass*deltaVy/dt;
    float f_angle = -atan2(Fy,Fx);

    if (((Fx != 0) || (Fy != 0)) && showarrows) {
//    if (((Fx != 0) || (Fy != 0)) && 0 ) {
    stroke(51,102,0); // makes the line green
    line(x_center,y_center,x_center+f_scaling*Fx,y_center+f_scaling*Fy);
    fill(51,102,0); // makes the triangle green
    triangle(x_center+f_scaling*Fx+sin(f_angle)*tri_width/2,y_center+f_scaling*Fy+cos(f_angle)*tri_width/2,x_center+f_scaling*Fx-sin(f_angle)*tri_width/2,y_center+f_scaling*Fy-cos(f_angle)*tri_width/2,x_center+f_scaling*Fx+cos(f_angle)*10,y_center+f_scaling*Fy-sin(f_angle)*10);
    }

//    float a_scaling=f_scaling;
    float a_scaling=2.0;
    float a_angle = f_angle;
    float ax = deltaVx/dt;
    float ay = deltaVy/dt;
    if (((ax != 0) || (ay != 0)) && showarrows) {
    stroke(204,0,204); // makes the line purple
    line(x_center,y_center,x_center+a_scaling*ax,y_center+a_scaling*ay);
    fill(204,0,204); // makes the triangle purple
    triangle(x_center+a_scaling*ax+sin(f_angle)*tri_width/2,y_center+a_scaling*ay+cos(f_angle)*tri_width/2,x_center+a_scaling*ax-sin(f_angle)*tri_width/2,y_center+a_scaling*ay-cos(f_angle)*tri_width/2,x_center+a_scaling*ax+cos(f_angle)*10,y_center+a_scaling*ay-sin(f_angle)*10);
    }

    scale(1,-1);
    translate(0,-height);  
    if (showarrows) {
    textSize(20);
    fill(255,0,0);
    text("Velocity",0.8*width,400);
    fill(51,102,0);
    text("Force",0.8*width,425);
    fill(0,0,255);
    text("Electric Field",0.8*width,450);
    fill(204,0,204);
    text("Acceleration",0.8*width,475);
    }

  stroke(0,0,0); // black
  float y_opening=38;
  line(x_plate_left,0,x_plate_left,0.467*height-y_opening/2);
  line(x_plate_left,0.467*height+y_opening/2,x_plate_left,height);

  line(x_plate_right,0,x_plate_right,0.467*height-y_opening/2);
  line(x_plate_right,0.467*height+y_opening/2,x_plate_right,height);

  int Narrows=8;
  for (int i = 1; i<=Narrows; i+=1)
  {
  fill(0,0,255);
  stroke(0,0,255);
//  float y_arrow = height*i/Narrows-15;
  float y_arrow = height*i/Narrows-43;
  line(x_plate_left+20,y_arrow,x_plate_right-20,y_arrow);
  if (E < 0) {
  triangle(x_plate_left+20,y_arrow-tri_width/2,x_plate_left+20,y_arrow+tri_width/2,x_plate_left+20-10,y_arrow);
  } 
  if (E > 0 ) {
  triangle(x_plate_right-20,y_arrow-tri_width/2,x_plate_right-20,y_arrow+tri_width/2,x_plate_right-20+10,y_arrow);
  }
  }

    fill(0,0,0); //If more text is written elsewhere make sure the default is black
    stroke(0,0,0); // If more lines are drawn elsewhere make sure the default is black


}


void wrapEdges() {
    float buffer = r*2;
    if (x > width +  buffer) x = -buffer;
    else if (x <    -buffer) x = width+buffer;
    if (y > height + buffer) y = -buffer;
    else if (y <    -buffer) y = height+buffer;
}


void drawEllipse(float _x, float _y, float _w, float _h){
  ellipse(_x, height - _y, _w, _h);  
}

void drawLine(float _x1, float _y1, float _x2, float _y2){
  line(_x1, height - _y1, _x2, height - _y2);  
}

void drawPoint(float _x, float _y){
  point(_x, height - _y);  
}

void drawQuad(float _x1, float _y1, float _x2, float _y2, float _x3, float _y3, float _x4, float _y4){
  quad(_x1, height - _y1, _x2, height - _y2, _x3, height - _y3, _x4, height - _y4);  
}

void drawRect(float _x, float _y, float _w, float _h){
  rect(_x, height - _y, _w, _h);  
}

void drawRect(float _x, float _y, float _w, float _h, float _r){
  rect(_x, height - _y, _w, _h, _r);  
}

void drawRect(float _x, float _y, float _w, float _h, float _tl, float _tr, float _br, float _bl){
  rect(_x, height - _y, _w, _h, _tl, _tr, _br, _bl);  
}

void drawTriangle(float _x1, float _y1, float _x2, float _y2, float _x3, float _y3){
  triangle(_x1, height - _y1, _x2, height - _y2, _x3, height - _y3);
}

void drawText(String _str, float _x, float _y) {
  text(_str, _x, height- _y);
}

void drawText(float _num, float _x, float _y) {
  text(_num, _x, height- _y);
}

void drawImage(PImage _img, float _x, float _y) {
  image(_img, _x, height - _y);
}

void drawImage(PImage _img, float _x, float _y, float _w, float _h) {
  image(_img, _x, height - _y, _w, _h);
}