Newbie-Question about variables

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9egenwind

Newbie-Question about variables

in Programming Questions • 8 months ago

float x;
float y;
int s = 10;

void setup() {
size(400, 400);
background(255, 245, 245);
smooth();
noStroke();

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

void draw() {
fill(200, 0, 0, 10);
x = x + random(-5, 5);
y = y + random(-5, 5);

x = constrain(x, 0, width);
y = constrain(y, 0, height);

ellipse(x, y, s, s);
}

Hi guys,
i need your help. I'm a newbie and im learning processing for a week. I solved
many understanding problems with the time by my own but here is a tutorial-code I don't get.

Why does this code start with:

float x; float y; int s = 10;

??

I have no clue why I can't put this part with …

x = width/2;
y = height/2;

… in the void draw() block?

Thanks for your help!

Replies(1)

GoToLoop

Re: Newbie-Question about variables

8 months ago

I believe you may have noticed that a regular Processing program consists of 3 parts:

Declare "global" field variables at the top.
Initialize necessary things within setup().
Draw things within the "virtual loop" draw().

If you don't declare -> float x; float y; int s = 10; @ the top,
they can't be used across functions.
Only within the function where they were created!

Actually, you're free to put -> x = width/2; y = height/2;
inside the draw() block.
However, that'd be extremely redundant!
B/c both width/2 & height/2 would result the same values always!
And draw() is called 60 FPS. While setup() is called once.

Hope you could figure out my explanations!

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