Processing with mouse click

DeDaymar

Hello,

I have to write a processing program which responds to a left mouseclick only. It's quite simple actually, the background hast to be red, if I click with my mouse the background has to turn green and when I click again it has to turn blue. And then again red etc. I am stuck at the point where I have to make a difference between the mouse clicks, like first mouse click second mouse click. I saw some examples on the internet but those weren't just with the left mousebutton only.

And should I use an void mousePressed() or not at all ?

I hope someone can give me some good directions.

GoToLoop

1. https://OpenProcessing.org/sketch/473642
2. https://Processing.org/reference/mouseButton.html
3. https://Forum.Processing.org/two/discussion/24960/how-to-go-back-to-original-colour-using-if-statements#Item_1

DeDaymar

@GoToLoop great this is exactly what I was looking for, but could you perhaps explain your code with comments? I find it quite a hard code, I don't understand everything. And since it is a school assignment, I should be able to explain what 'wrote'

GoToLoop

The code is about 20 lines only. It'd be easier if you could point out exactly what you don't get it. :\">

kfrajer

You can check in this link: https://processing.org/reference/ as it will answer most of your questions.

Kf

DeDaymar

@GoToLoop yes ofcourse you're right, my bad.

    static final boolean JAVA = 1/2 != 1/2.;  //why 1/2 and static
    static final color[] PALETTE = { #FF0000, #008000, #0000FF }; //this is hex
    int idx;   //what other word would you use here

    void setup() {
      size(300, 200);
      noLoop();
      colorMode(RGB);
    }

    void draw() {
      final color c = PALETTE[idx]; //so [] means it's an array right?
      background(c);
      if (JAVA)  getSurface().setTitle("Color: " + idx + "  -  #" + hex(c, 6)); //Could you explain what happens here precisely?
    }

    void mousePressed() {
      keyPressed();
    }

    void keyPressed() {
      idx = (idx + 1) % PALETTE.length; //and here as well.
      redraw();
    }

It's quite a lot as you can see, I'm really in the beginning of processing. I have a lot discover, so if you think I should be able to figure some lines out myself, I understand that. But I hope you can help me understand this, because I think this a very nice and small program.

GoToLoop

static final boolean JAVA = 1/2 != 1/2.; //why 1/2 and static

1. The expression 1/2 != 1/2. evaluates as true for Java and as false for JS, b/c for the former, the result of a division operation when both operands are integers, the decimal part is removed.
2. A field declared as static isn't instantiated when it's class is instantiated: https://Processing.org/reference/static.html

static final color[] PALETTE = { #FF0000, #008000, #0000FF }; //this is hex

Web-color RGB notation https://Processing.org/reference/color_datatype.html

int idx; //what other word would you use here

Field idx represents the current index of the PALETTE array.

final color c = PALETTE[idx]; //so [] means it's an array right?

Field PALETTE was clearly declared as color[] datatype at the top of the sketch, right?
See [] array access: https://Processing.org/reference/arrayaccess.html

GoToLoop

setTitle("Color: " + idx + " - #" + hex(c, 6)); //Could you explain what happens here precisely?

• That's a String concatenation via operator +.
• Read about hex() here: https://Processing.org/reference/hex_.html
• Method setTitle() changes the current text displayed at the window's top-bar.

GoToLoop

idx = (idx + 1) % PALETTE.length; //and here as well.

Operator % is called modulo or remainder of a division operation:
https://Processing.org/reference/modulo.html

Given the remainder value never reaches the divisor value, instead the remainder cycles back to 0, it is a nice trick to constrain the current index to always stay within an array's valid range length . :ar!

DeDaymar

@GoToLoop you are absolutely amazing, thank you very much for explaining everything to me ! I understand your code much better now