moving into object oriented programming

Programming Questions

2bad4you

moving into object oriented programming

in Programming Questions • 2 years ago

Hi,

I am a beginner at Processing so forgive me if my question is stupid/simple.

This is Roger following the mouse:

void setup() {
size (400, 400);
}
void draw() {
background (255);
ellipseMode(CENTER);
noStroke();
fill(156, 109, 203);
//main body
ellipse(mouseX, mouseY, 180, 180);
//ears
ellipse(mouseX-20, mouseY-90, 40, 120);
ellipse(mouseX+20, mouseY-90, 40, 120);
//eyes
fill(0, 0, 0);
ellipse(mouseX-15, mouseY-30, 30, 30);
ellipse(mouseX+15, mouseY-30, 30, 30);
fill(255, 255, 255);
ellipse(mouseX-7, mouseY-24, 10, 10);
ellipse(mouseX+7, mouseY-24, 10, 10);
//lips
smooth();
strokeWeight(10);
stroke(255);
line(mouseX-40, mouseY+20, mouseX+40, mouseY+20);
}

It works just fine. However, when I wanted to translate it into object oriented code something doesn't work and I don't really know why.

Roger roger;
void setup() {
size (500, 500);
background(255);
roger = new Roger(200, 180, 180, 180);
}
void draw() {
roger.display();
roger.rabbitFollowsMouse();
}
class Roger {
float a;
float b;
float c;
float d;
Roger (float a, float b, float c, float d) {
a = a;
b = b;
c = c;
d = d;
}
void display() {
noStroke();
fill(156, 109, 203);
//main body
ellipse(a, b, c, d);
//ears
ellipse(a-20, b-90, c-140, d-60);
ellipse(a+20, b-90, c-140, d-60);
//eyes
fill(0);
ellipse(a-15, b-30, c-150, d-150);
ellipse(a+15, b-30, c-150, d-150);
fill(255);
ellipse(a-7, b-27, c-170, d-170);
ellipse(a+7, b-27, c-170, d-170);
//lips
smooth();
strokeWeight(10);
stroke(255);
line(a-40, b+20, c+60, d+20);
}
void rabbitFollowsMouse() {
a = mouseX;
b = mouseY;
//main body
ellipse(mouseX, mouseY, c, d);
//ears
ellipse(mouseX-20, mouseY-90, c-140, d-60);
ellipse(mouseX+20, mouseY-90, c-140, d-60);
//eyes
ellipse(mouseX-15, mouseY-30, c-150, d-150);
ellipse(mouseX+15, mouseY-30, c-150, d-150);
ellipse(mouseX-7, mouseY-24, c-170, d-170);
ellipse(mouseX+7, mouseY-24, c-170, d-170);
//lips
line (mouseX-40, mouseY+20, c+60, d+20);
}
}

Can anyone see any mistakes?

Thanks is advance!

2bad

Replies(2)

PhiLho

Re: moving into object oriented programming

2 years ago

You don't say goes wrong, so I will address one issue:

Roger (float a, float b, float c, float d) {
a = a;
b = b;
c = c;
d = d;
}

does nothing...
You assign each parameter to itself, then they vanish.
First task: make meaningful variable names. Like x, y for coordinates, w, h for width and height, or such.
Second task: either name differently your class fields or parameters, or use the common idiom this.a = a;

amnon.owed

Re: moving into object oriented programming

2 years ago

On a more general note. Check out this link: http://processing.org/learning/objects/

On a side note. I also recommend the book by Daniel Shiffman where the above tutorial comes from.

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