我不明白为什么我的线要倾斜

Question

I am in this AP class in highschool and we are using the program JAVA or OOP, I don't even know what it is. In the class we don't have a teacher so we basically have to self teach our self from a packet. I am learning how to draw a face and i am kind off struggling.

Well first off, the prompt here- http://mrlanda.com/ecs/unit%205/Happy%20Face.htm

Look at the picture below to see how it looks like.

MY QUESTION-- Well here is what i got so far and it is stressing me out so much, I DON'T KNOW WHY BUT MY LINE KEEPS GOING IN AN ANGLE. Why does it go in an angle when I am not telling it too.. I am also having a problem with the nose i can't seem to find the spot i want to put it at it keeps going into an angle for some reason.

My code so far

import apcslib.*; 
public class DrawSquare 
{ 
    public static void main(String[] args) 
    { 
        DrawingTool marker; 
        SketchPad poster; 

        poster= new SketchPad(600,600); 
        marker= new DrawingTool(poster); 

        //left side of box
        marker.up(); 
        marker.move(0,0); 
        marker.down(); 
        marker.turnRight(180); 
        marker.forward(200); 

        //mouth
        marker.up(); 
        marker.move(40,60); 
        marker.down(); 
        marker.turnRight(90); 
        marker.forward(100); 

        //nose
        marker.up(); 
        marker.move(100,100); 
        marker.down(); 
        marker.turnRight(90); 
        marker.forward(100); 

    }
}    

Answer 1

According to the API docs for DrawingTool the method move(double, double) changes the direction of your drawing tool.

Hence if you perform the move to (40,60) from the endpoint (-200,0) of your previous forward move your new direction vector will be (240,60) . When rotating this by 90 degrees you will head in direction of (60,-240) .

I've made a sketch showing the behaviour (not exactly to scale - I hope I haven't mixed coordinates)...

So you have the following options to fix this:

1. instead moving to (40,60) directly you could move to a temporary point before forcing the move to have your desired direction:

    // mouth marker.up(); marker.move(40,50); marker.move(40,60); // now you have direction "up" marker.down(); marker.forward(100); 

2. or you could just use move instead of `forward

    // mouth marker.up(); marker.move(40,60); marker.down(); marker.move(40,160); // or whatever your expected target is...