How to apply changes to a particular object of the class in Processing?

Elmpt · January 7, 2021, 10:29am

Hi! I am a little confused with the handling of objects. I have created class “Stone” and then I have created 3 objects Stone stone1, stone2, stone3 in the main scetch. What I need is to make a stone transparent when user moves it. The problem is that when the stone is moved, all 3 stones that I have created become transparent, not the particular stone that was moved. Can you please give me a hint, how can I apply transparency just for the moved stone?
My “Stone” class:

   class Stone {
    Playfield p;
    PImage stone;
    boolean overStone = false;
    boolean locked = false;
    boolean stoneMoved;
    int positionX;
    int positionY;
    int stoneXOld;
    int stoneYOld;
    int stoneSize;
    boolean transparencyOn;

    Stone(int stoneXtemp, int stoneYtemp, int stoneSizeTemp, Playfield pf) {
        stone = loadImage("stone.png");

        positionX = stoneXtemp;
        positionY = stoneYtemp;
        stoneXOld = positionX;
        stoneYOld = positionY;

        imageMode(CENTER);
        stoneSize = stoneSizeTemp;
        p = pf;
    }

    void display() {
        if (transparencyOn == true) {
            tint(255, 126);
        } else {
            noTint();
        }
        image(stone, positionX, positionY, stoneSize, stoneSize);
    }

    void update() {
        if (mouseX > positionX - stoneSize / 2 && mouseX < positionX + stoneSize / 2 &&
                mouseY > positionY - stoneSize / 2 && mouseY < positionY + stoneSize / 2) {
            overStone = true;
            if (!locked) {
                tint(160);
            }
        } else {
            noTint();
            overStone = false;
        }
    }

    void interact() {
        if (overStone && mousePressed) {
            locked = true;
            tint(230);
            positionX = mouseX;
            positionY = mouseY;
        } else {
            locked = false;
            noTint();
        }
    }
    
    boolean stoneMoved() {
        return stoneMoved = (!overStone && !locked && positionX > stoneXOld + 100 && positionY > stoneYOld + 100);
    }

    void afterMove() {
           transparencyOn = true;  

    }
}

My main scetch:

import processing.video.*;
Movie water;
Stone stone1,stone2,stone3;
PImage img;

void setup()
{
size(800,800);
water=new Movie(this,"Water.mp4");
water.loop();

stone1=new Stone(70,70,100,this);
stone2=new Stone(180,70,80,this);
stone3=new Stone(270,70,60,this);

}

void draw(){
background(water);

stone1.display();
stone2.display();
stone3.display();

stone1.update();
stone2.update();
stone3.update();

stone1.interact();
stone2.interact();
stone3.interact();
}

void movieEvent(Movie m){
m.read();
}

void mouseReleased(){
stone1.afterMove();
stone2.afterMove();
stone3.afterMove();
}

glv · January 7, 2021, 10:56am

Hello,

Please provide a minimal example that we can work with.

I was interested but… try the sketch you posted and you will see why.

:)

Chrisir · January 7, 2021, 10:58am

You can’t rely on tint() outside display()

Instead

set transparencyOn correctly everywhere and
evaluate it in display() to set tint / noTint

Elmpt · January 7, 2021, 11:16am

That’s my bad. I tried to delete code that is irrelevant for the issue and didn’t see that some things don’t match. I edited post, thanks

quark · January 7, 2021, 11:16am

As said above only use tint() when you are actually rendering the object. Also you can isolate changes in drawing style using push/pop style like this

    void display() {
        pushStyle();
        if (transparencyOn == true) {
            tint(255, 126);
        } else {
            noTint();
        }
        image(stone, stoneX, stoneY, stoneSize, stoneSize);
        popStyle();
    }

quark · January 7, 2021, 11:20am

You still have a call to tint() inside the interact and update methods which is not good. Create an attribute in the Stone class to store the tint level you want during interaction etc then use it in display method

Elmpt · January 7, 2021, 11:25am

got it, I’m going to try it now

Elmpt · January 7, 2021, 12:33pm

I added 2 attributes:

int tintLevel;
int base;

initialise them in constructor:

base = 255;
tintLevel = 255;

in display() I use tint() with base, tintLevel

tint(base,tintLevel);

and then in code instead of tint(), I change just tintLevel value
e.g: tintLevel=126;

should it be something like that?

quark · January 7, 2021, 12:34pm

Yes and don’t forget the push popStyle calls this will ensure that each stone is rendered without regard to the others.

Chrisir · January 7, 2021, 12:40pm

What did you intend your variable transparencyOn for?

Elmpt · January 7, 2021, 12:43pm

Firstly I wanted to use it to mark when I need the stone to be transparent and when I do not need it. Now I think I would better create method to set transparency, not sure

Chrisir · January 7, 2021, 12:45pm

Well yeah… you made 2 new attributes now, ignoring transparencyOn which already had the job in the first place…

just reread my first post

Chrisir · January 7, 2021, 2:21pm

more complicate than I thought it was

I made a global var drag that tells us when ANY stone is dragged, then the others are ignored.

(bit of house cleaning might be required)



import processing.video.*;

// Movie water;

Stone stone1, stone2, stone3;

PImage img;

boolean drag=false; 

void setup()
{
  size(800, 800);
  //water=new Movie(this,"Water.mp4");
  //water.loop();

  stone1=new Stone(70, 70, 100 );
  stone2=new Stone(180, 70, 80 );
  stone3=new Stone(270, 70, 60 );
}

void draw() {
  background(0); // water 

  stone1.display();
  stone2.display();
  stone3.display();

  stone1.update();
  stone2.update();
  stone3.update();

  stone1.interact();
  stone2.interact();
  stone3.interact();
}

void mousePressed() {
  stone1.initMove();
  stone2.initMove();
  stone3.initMove();
}

void mouseReleased() {

  drag=false; 
  stone1.afterMove();
  stone2.afterMove();
  stone3.afterMove();
}

// ===========================================================================================

class Stone {
  // Playfield p;
  PImage stone;

  boolean overStone = false;
  boolean locked = false;
  boolean stoneMoved;
  int positionX;
  int positionY;
  int stoneXOld;
  int stoneYOld;
  int stoneSize;
  boolean transparencyOn;

  Stone(int stoneXtemp, int stoneYtemp, 
    int stoneSizeTemp) {
    stone = loadImage("stone.jpg");

    positionX = stoneXtemp;
    positionY = stoneYtemp;
    stoneXOld = positionX;
    stoneYOld = positionY;

    imageMode(CENTER);
    stoneSize = stoneSizeTemp;
    //p = pf;
  }

  void display() {
    if (transparencyOn == true) {
      tint(255, 126);
    } else {
      noTint();
    }
    image(stone, 
      positionX, positionY, 
      stoneSize, stoneSize);
  }

  void update() {
    if (mouseX > positionX - stoneSize / 2 &&
      mouseX < positionX + stoneSize / 2 &&
      mouseY > positionY - stoneSize / 2 && 
      mouseY < positionY + stoneSize / 2) {
      overStone = true;
      if (!locked&&!drag) {
        transparencyOn=true;
      }
    } else {
      transparencyOn=false; 
      overStone = false;
    }
  }

  void initMove() {
    if (drag)
      return; // leave

    if (overStone && mousePressed) {
      locked = true;
      drag=true;
    } else {
      locked = false;
    }
  }

  void interact() {
    if (drag&&locked) {
      positionX = mouseX;
      positionY = mouseY;
    }
  }

  boolean stoneMoved() {
    return stoneMoved = (!overStone && !locked && positionX > stoneXOld + 100 && positionY > stoneYOld + 100);
  }

  void afterMove() {
    transparencyOn = true;
    locked = false;
  }
}

Elmpt · January 7, 2021, 2:37pm

Oh, Thanks a lot, I’ll try it now!

Elmpt · January 7, 2021, 2:41pm

Oh! so I can use drag from all the classes in project! That is astonishing!

Elmpt · January 7, 2021, 3:05pm

This is top! I have added some more things that I need, and it seems to be working perfectly!

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How to apply changes to a particular object of the class in Processing?

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