# Updating global variables inside draw() function

**URL:** <https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945>\
**Category:** Coding Questions\
**Created:** [October 25, 2019, 4:35pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945 "2019-10-25T16:35:17Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ale2200](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@Ale2200](https://discourse.processing.org/u/Ale2200)\
**Post date:** [October 25, 2019, 4:35pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/1 "2019-10-25T16:35:17Z")

</div>

I cannot update global variables in the Draw() function and I think that is because it would be problematic to deal with a variable that gets updated x times per second (I suppose?), sorry but I’m totally new to p5js. How can I update these variables during the running of my program since any attempt to update them inside the draw() has so far been useless? Thanks a lot

Edit: Here’s the source code

//WARNING: SHITCODE AHEAD!!!  
//////////////////////////////////////////////////////////////////////  
var myMatrix = [];  
var humanStats = []  
var humanDiseases = [“none”,“influenza”,“tuberculosis”,“bronchitis”,“typhus”,“salmonella”];  
var humanDiseasesE = [“none”,“cysticFibrosisE”,“duchenneMuscularDystrophyE”,“hypertensionE”,“arthritisE”, “diabetesE”]  
var humanDiseasesResistance = [“none”,“influenza”,“tuberculosis”,“bronchitis”,“typhus”,“salmonella”,“cysticFibrosisE”,“duchenneMuscularDystrophyE”,“hypertensionE”,“arthritisE”, “diabetesE”];  
var humanEnvironmentResistance = [“none”,“cold”,“food”,“danger”];  
var childContainer = [];  
var childN = 0;  
var sideLength = 100;  
var checkStartButton = false;  
var horizontalPositionArray= [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990];  
var verticalPositionArray= [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990];  
var randomSpawnX = undefined;  
var randomSpawnY = undefined;

function createMatrix(sideLength){

for (var i = 0; i \< sideLength; i++) {

```
myMatrix[i] = [];

for (var j = 0; j < sideLength; j++) {

    myMatrix[i][j] = 0;

	}
}

```

}

function randomFromInterval( min, max ){

var random = Math.random() \* ( max - min + 1 ) + min;

if ( random \> max ){

```
random = max;

```

}

return random;  
}

function randomBoolean(){

return Math.random() \>= 0.5;  
}

function initializeRandomStats( sideLength ){

for ( var i = 0; i \< sideLength; i++ ){

humanStats[i]= { id: i, xPos: 0, yPos: 0, strength: randomFromInterval(1,10), agility : randomFromInterval(1,10), sight: randomFromInterval(1,10), hearing: randomFromInterval(1,10), intelligence: randomFromInterval(1,10), disease: Math.floor(randomFromInterval(0,5)), diseaseE: Math.floor(randomFromInterval(0,5)), diseaseResistance: Math.floor(randomFromInterval(0,10)), environmentResistance: Math.floor(randomFromInterval(0,3)), aggressiveness: randomBoolean };

}  
}

function inheritedDiseaseE( id1, id2 ){

if ( humanStats[id1].diseaseE == humanStats[id2].diseaseE ){

```
return humanStats[id1].diseaseE;

```

}

if ( humanStats[id1].diseaseE == 0 ){

```
return humanStats[id2].diseaseE;

```

}

if ( humanStats[id2].diseaseE == 0 ){

```
return humanStats[id1].diseaseE;

```

}

if ( randomBoolean == true ){

```
return humanStats[id1].diseaseE;

```

} else {

```
return humanStats[id2].diseaseE;

```

}  
}

function inheritedDiseaseResistance( id1, id2 ){

if ( humanStats[id1].diseaseResistance == humanStats[id2].diseaseResistance ){

```
return humanStats[id1].diseaseResistance;

```

}

if ( humanStats[id1].diseaseResistance == 0 ){

```
return humanStats[id2].diseaseResistance;

```

}

if ( humanStats[id2].diseaseResistance == 0 ){

```
return humanStats[id1].diseaseResistance;

```

}

if ( randomBoolean == true ){

```
return humanStats[id1].diseaseResistance;

```

} else {

```
return humanStats[id2].diseaseResistance;

```

}  
}

function inheritedEnvironmentResistance( id1, id2 ){

if ( humanStats[id1].environmentResistance == humanStats[id2].environmentResistance ){

```
return humanStats[id1].environmentResistance;

```

}

if ( humanStats[id1].environmentResistance == 0 ){

```
return humanStats[id2].environmentResistance;

```

}

if ( humanStats[id2].environmentResistance == 0 ){

```
return humanStats[id1].environmentResistance;

```

}

if ( randomBoolean == true ){

```
return humanStats[id1].environmentResistance;

```

} else {

```
return humanStats[id2].environmentResistance;

```

}  
}

function inheritedAggressiveness( id1, id2 ){

if ( humanStats[id1].aggressiveness == humanStats[id2].aggressiveness ){

```
return humanStats[id1].aggressiveness;

```

} else {

```
return randomBoolean;

```

}  
}

function checkDiseaseResistanceE( childN ){

if ( childContainer[childN].diseaseE == childContainer[childN].diseaseResistance ){

```
return 0;

```

} else {

```
return childContainer[childN].diseaseE;

```

}  
}

function createChild( id1, id2, childN ){

childContainer[childN]= { id: humanStats.length + childN, strength: (humanStats[id1].strength + humanStats[id2].strength) / 2, agility: (humanStats[id1].agility + humanStats[id2].agility) / 2, sight: (humanStats[id1].sight + humanStats[id2].sight) / 2, hearing: (humanStats[id1].hearing + humanStats[id2].hearing) / 2, intelligence: (humanStats[id1].intelligence + humanStats[id2].intelligence) / 2, disease: 0, diseaseE : inheritedDiseaseE( id1, id2 ), diseaseResistance: inheritedDiseaseResistance( id1, id2 ), environmentResistance: inheritedEnvironmentResistance( id1, id2 ), aggressiveness: inheritedAggressiveness( id1, id2 )};

childContainer[childN].diseaseE = checkDiseaseResistanceE( childN );

childN++;

spawnRandomPosition();

myMatrix[randomSpawnX][randomSpawnY]= childContainer[childN].id;

}

function printRawMatrix( sideLength ){

for ( var i = 0; i \< sideLength; i++ ){

```
document.write("<br>");

for ( var j = 0; j < sideLength; j++ ){

    document.write(myMatrix[i][j]);

}

```

}  
}

function shuffleHeightWidthArrays(){

// Fisher–Yates shuffle  
horizontalPositionArray = \_.shuffle(horizontalPositionArray);  
verticalPositionArray = \_.shuffle(verticalPositionArray);

}

function initializeSimulation(){

createMatrix( sideLength );  
initializeRandomStats( sideLength );  
shuffleHeightWidthArrays();

for ( var i = 0; i \< sideLength; i++ ){

myMatrix[verticalPositionArray[i] / 10 ][horizontalPositionArray[i] / 10 ] = humanStats[i].id;  
humanStats[i].xPos = horizontalPositionArray[i] / 10;  
humanStats[i].yPos = verticalPositionArray[i] / 10;

}  
}

function initializePrinting(){

```
	for ( var i = 0; i < sideLength; i++ ){

	  
	fill(color(0,0,255));
	rect( horizontalPositionArray[i], verticalPositionArray[i] , 10, 10 );  
  
}

```

}

function startPrint(){

```
checkStartButton = true;

```

}

function spawnRandomPosition(){

```
var cycleCheck = false;

while ( cycleCheck == false ){

	randomSpawnX= horizontalPositionArray[Math.floor(randomFromInterval(0,99))];
	randomSpawnY= verticalPositionArray[Math.floor(randomFromInterval(0,99))];

	if ( myMatrix[randomSpawnY][randomSpawnX] != 0 ){

		cycleCheck= true;
	}
}

```

}

var checkChildButton= false;  
function printChild(){

```
checkChildButton= true;

```

}

function printCanvasChild(){

```
fill(color(0,255,0));
rect( randomSpawnX, randomSpawnY, 10, 10 );

```

}  
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

function setup() {

```
createCanvas(1000, 1000); 
background(255);

initializeSimulation();

for (var x = 0; x < width + 10; x = x + (width / sideLength) ) {

		for (var y = 0; y < height + 10 ; y = y + (height / sideLength) ) {

	
			stroke(0);
			strokeWeight(1);
			line(x, 0, x, height);
			line(0, y, width, y);
	
    	}   
  }

```

}

function draw() {

```
if ( checkStartButton == true ){

	initializePrinting();
	checkStartButton= false;
	document.getElementById("startButton").disabled = true;
}

if ( checkChildButton == true ){

	spawnRandomPosition();///
	createChild(0,1, childN);///
	printCanvasChild();
	checkChildButton= false;
	document.getElementById("childButton").disabled = true;
	console.log(randomSpawnX);

}

```

}

---

<div class="post-metadata">

**Author:** ![earthbound](https://avatars.discourse-cdn.com/v4/letter/e/8c91f0/32.png) [@earthbound](https://discourse.processing.org/u/earthbound)\
**Post date:** [October 25, 2019, 4:55pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/2 "2019-10-25T16:55:23Z")

</div>

Post the source code? Then maybe someone can diagnose what is going on.

---

<div class="post-metadata">

**Author:** ![Ale2200](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@Ale2200](https://discourse.processing.org/u/Ale2200)\
**Post date:** [October 25, 2019, 5:28pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/3 "2019-10-25T17:28:41Z")

</div>

Thanks, I’ve posted it right now

---

<div class="post-metadata">

**Author:** ![Ale2200](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@Ale2200](https://discourse.processing.org/u/Ale2200)\
**Post date:** [October 27, 2019, 3:38pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/4 "2019-10-27T15:38:23Z")

</div>

Problem solved, It was due to some variables not having a value assigned to them, that’s why the program would block. The array cell which were being called weren’t initialized at all.

---

<div class="post-metadata">

**Author:** ![Chrisir](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/chrisir/32/45_2.png) [@Chrisir](https://discourse.processing.org/u/Chrisir)\
**Post date:** [October 27, 2019, 4:12pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/5 "2019-10-27T16:12:50Z")

</div>

> [@Ale2200](#):
>
> it would be problematic to deal with a variable that gets updated x times per second

Not at all.

On the contrary, the purpose of a running program is to handle and to work with changing variables.

When you think of a game, everything changes fast

---

<div class="post-metadata">

**Author:** ![Ale2200](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@Ale2200](https://discourse.processing.org/u/Ale2200)\
**Post date:** [October 27, 2019, 4:17pm UTC](https://discourse.processing.org/t/updating-global-variables-inside-draw-function/14945/6 "2019-10-27T16:17:14Z")

</div>

Yeah, that makes sense, thanks for the response ^^