Processing 1.0 - Processing Discourse - Beginner scope question

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Index › Programming Questions & Help › Syntax Questions › Beginner scope question

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Beginner scope question (Read 220 times)

s3gfault

Beginner scope question
Mar 20^th, 2009, 4:04pm

I've this code in a presentation:
Code:

int i;
void setup() 
{
  i = 50;
  size(400, 400);
  rectMode(CENTER);
}
void draw() {
  background(192, 64, 0);
  stroke(255);
  fill(255);
  rect(200, 200, 50, 50);
  noStroke();
  fill(#3E3AB4, i);
  ellipse(mouseX, mouseY, 75, 75);
}
void mousePressed() {
  i = i + 1;
}

The idea is that when you click the mouse, the circle gets darker, until it's opaque. Clicking the mouse doesn't do anything though. i've tried different variations on line 1, such as "public int i;", "public static int i;" and "static int i;". The second to last line was originally "i++;" and that didn't work either.

Any suggestions? I'm looking for an explanation of why this doesn't work, rather than a different implementation that achieves the same results.

TVS

Re: Beginner scope question
Reply #1 - Mar 20^th, 2009, 4:13pm

In fact it does work, just not fast.

Two things you need to know:
1. opacity goes from 0-255, where 255 is 100% opacity.
2. a change of opacity between 50 and 51 is not visible. Even between 50 and 60 is difficult to see. To save you from RSI, I suggest to raise your steps from 1 to 10 or even bigger.

Soluation for your script:
i=i+1 --> i=i+10 (or i+=10, which is the same)

Now it should work

p.s. You can also already give a value to int i when initializing it, so:
int i; --> int i = 50; (and remove the line 'i=50;' from your setup void)

s3gfault YaBB Newbies Offline Posts: 2	Re: Beginner scope question Reply #2 - Mar 20^th, 2009, 5:11pm AHA! thanks that was driving me crazy. sry for the noise

cloister Full Member Offline Posts: 138	Re: Beginner scope question Reply #3 - Mar 20^th, 2009, 5:32pm Also, you might want to change from mousePressed(), which only gets called when the user _releases_ the mouse button, to mouseDown(), which I believe fires continuously until the user lets go.

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