Trying to Reduce the Number of Global Variables

Processing Coding Questions
1 
int x, y;
int xSpeed = 0;
int ySpeed = 0;
int diam = 50;
int xConstr;
int yConstr;

void setup()
{
  size(400,400);
  smooth();
  x = width / 2;
  y = height / 2;
}

void draw()
{
  drawBackground();
  
  drawObject();
  
  moveObject();
  
  addMotion();
}

void drawBackground()
{
  background(255);
}

void drawObject()
{ 
  constrainObject();
  ellipse(xConstr, yConstr, diam, diam);
}

void moveObject()
{ 
  x = x + xSpeed;
  y = y + ySpeed;
}

void addMotion()
{
  
  if(keyPressed)
  {
    if(keyCode == RIGHT)
    {
      xSpeed = 1;
    }
    if(keyCode == LEFT)
    {
      xSpeed = -1;
    }
    if(keyCode == UP)
    {
      ySpeed = -1;
    }
    if(keyCode == DOWN)
    {
      ySpeed = 1;
    }
  }
  else
  {
    xSpeed = 0;
    ySpeed = 0;
  }
}

void constrainObject()
{
  yConstr = constrain(y, diam / 2, height - diam / 2);
  xConstr = constrain(x, diam / 2, width - diam / 2);
}

Thatā€™s the code iā€™m currently working on. I need to reduce the amount of global variables and create more passing arguments but iā€™m not really sure how to go about it.

Thanks!

2

Have a look at this tutorial: https://processing.org/tutorials/objects/
Then attempt to make some changes. If you run into a road block, ask here and provide your attempt.

Kf

3

Hi @QuazArxx,

You can format your code by using the </> button when you paste some in the forum. Try and edit your post !

As for your problem why do you need to get rid of those global variables ? In your case, since you are using them in draw, you canā€™t really do otherwise.

You can use classes as @kfrajer mentioned to order your code a bit more but youā€™ll still have some global variables.

4

I had already attempted to move variables around within functions first and nothing seemed to work so I moved them all to global.

I donā€™t technically HAVE to, but itā€™s for a school project and in order for me to get the maximum grade possible I need to eliminate global variables and use passing arguments in my functions.

5

Based on what is taught in your school, what options do you have?

What have you tried it? Show your attempt.

Kf

6

Iā€™m not sure how to show my attempt if whatever I did I had errors because it couldnā€™t find the variables because they werenā€™t global.

The only option I have otherwise is leave it all global with no arguments in the functions and get a score as high as 8/10****

7 
int x, y;
int xSpeed = 0;
int ySpeed = 0;
int diam = 50;
int xConstr;
int yConstr;

void setup()
{
  size(400,400);
  smooth();
  x = width / 2;
  y = height / 2;
}

void draw()
{
  drawBackground();
  
  drawWin();
  
  drawObject();
  
  moveObject();
  
  resetObject();
  
  addMotion();
}

void drawBackground()
{
  background(0);
  rect(20, 30, 280, 320);
}

void drawWin()
{
  int minHeight = 250;
  int maxHeight = 330;
  
  fill(0, 255, 0);
  noStroke();
  rect(280, 250, 20, 80);
}

void drawObject()
{ 
  fill(255);
  stroke(10);
  constrainObject();
  ellipse(xConstr, yConstr, diam, diam);
}

void moveObject()
{ 
  x = x + xSpeed;
  y = y + ySpeed;
}

void resetObject()
{
  if(x > 300 - diam / 2 || x < 20 + diam / 2)
  {
    x = width / 2;
    y = height / 2;
  }
  if(y > 350 - diam / 2 || y < 30 + diam / 2)
  {
    x = width / 2;
    y = height / 2;
  }
}

String printWin()
{
  if(drawWin.minHeight > y < drawWin.maxHeight)
  {
    text("You win!", 100, 100);
  }
}
    

void addMotion()
{
  
  if(keyPressed)
  {
    if(keyCode == RIGHT)
    {
      xSpeed = 1;
    }
    if(keyCode == LEFT)
    {
      xSpeed = -1;
    }
    if(keyCode == UP)
    {
      ySpeed = -1;
    }
    if(keyCode == DOWN)
    {
      ySpeed = 1;
    }
  }
  else
  {
    xSpeed = 0;
    ySpeed = 0;
  }
}

void constrainObject()
{
  xConstr = constrain(x, 20 + diam / 2, 300 - diam / 2);
  yConstr = constrain(y, 30 + diam / 2, 350 - diam / 2);
}

drawWin() and printWin() are 2 new functions I added. In printWin if I try to call the variables declared in drawWin, I get an error stating ā€œThe variable ā€˜drawWinā€™ does not existā€. Of course it doesnā€™t exist because itā€™s not a variable.

Also yes I know I donā€™t have a return for printWin just yet. I was starting to set it up til i ran into the error stated.

8

You canā€™t use drawWin.minHeight or drawWin.maxHeight, it is not how it works.

You should read about variables scope: https://processing.org/examples/variablescope.html

For your problem you have basically 2 ways of sharing your variables:

  • Declare them in the global scope (outside any function) - wich you try to avoid
  • Use parameters for function

Letā€™s say I want to code an addition function that takes 2 numbers and add them together. Then my function would look something like this:

float addition(float a, float b) {
    return a + b;
}

This way, I can send numbers to that function from another part of the code:

void setup() {
    float num1 = 2.0;
    float num2 = 5.0;

    float result = addition(num1, num2); // Result will be 7.0
}
1 Like
9

I know about scoping but thatā€™s why iā€™m confused Even with what you tell me iā€™m not sure how I can do that with my code. Itā€™s getting difficult to think about this code due today. with all the variables declared in global, iā€™m not sure how to make those available only in the functions that theyā€™re used in.