ij-macro-programming-workshop
Exercise 11.02 - user defined functions
Aim:
- understand variable scope and global variables
Turtle graphics consist of a turtle that is placed on an image and that understands the commands
forward(n)right(a)left(a)
Complete the function right below then use the commands to draw a rectangle.
Note: a -= 10 is a short way to write a = a - 10. It works the same way for +=.
var _X = 0;
var _Y = 0;
var _ANGLE = 0;
var _RADIUS = 20;
var _DELAY = 400;
newImage("turle graphics", "8-bit white", 1600, 1200, 1);
setForegroundColor(0,0,0);
initializeTurtle();
Your code starts after this line
forward(100);
right(90);
forward(50);
right(90);
forward(100);
right(90);
forward(50);
right(90);
Your code ends before this line
function initializeTurtle() {
_X = getWidth() / 2;
_Y = getHeight() / 2;
moveTo(_X, _Y);
makeOval(_X - (_RADIUS / 2), _Y - (_RADIUS / 2), _RADIUS, _RADIUS);
Roi.setFillColor("green");
}
function forward(step) {
_X += step * cos(_ANGLE * PI / 180);
_Y += step * sin(_ANGLE * PI / 180);
lineTo(_X, _Y);
Roi.move(_X - (_RADIUS / 2), _Y - (_RADIUS / 2));
wait(_DELAY);
}
function right(delta) {
Your code starts after this line
_ANGLE += delta % 360;
Your code ends before this line
}
function left(delta) {
_ANGLE -= delta % 360;
}
