# Twist in the Dark : An animation of the shapes in polar coordinates.

## Description of how to make this creative coding animation.

It's a creative coding animation made with Processing. It draws some shapes that are calculated in polar coordinates.

I used to do not use global variables in my code. But I tried to use global variables to make an animation this time on a whim.

### It calculates some wave shape with this code.

float fX = width * iRatio;float fY = height * (0.5 + 0.4 * waveCalc(iRatio, radians));

### Then, it translates the wave shape into polar coordinates.

float x = fY * cos(fX) * 0.5;float y = fY * sin(fX) * 0.5;

### I used beginShape() to draw.

beginShape(TRIANGLES);

beginShape(LINES);

## Processing example code.

Please feel free to use this example code.To see other works based on my code is my pleasure. And my honor.

```
/**
* Twist in the Dark.
* trying to use global variables to make an animation.
*
* Processing 3.5.3
* @author @deconbatch
* @version 0.1
* created 0.1 2020.06.27
*/
int frmMax = 24 * 3;
int ptnMax = 6;
int initPlot = floor(random(100));
float initHue = random(360.0);
float initRad = 0.0;
public void setup() {
size(720, 720);
colorMode(HSB, 360, 100, 100, 100);
rectMode(CENTER);
smooth();
frameRate(24);
}
public void draw() {
int frmCnt = frameCount - 1; // because of frameCount start from 1
if (frmCnt >= frmMax * ptnMax - 1) {
exit();
}
if (frmCnt % frmMax == 0) {
resetPtn();
}
// moving factor
float radians = initRad + easeInOutCosine(map(frmCnt % frmMax, 0, frmMax, 0.0, 1.0)) * TWO_PI * 2;
translate(width * 0.5, height * 0.5);
background(initHue % 360.0, 40.0, 90.0, 100.0);
strokeWeight(3.0);
stroke(initHue % 360.0, 40.0, 90.0, 100.0);
fill((initHue + 90) % 360.0, 90, 10, 100);
// draw shapes
beginShape(TRIANGLE_FAN);
vertex(0.0, 0.0);
int plotNum = initPlot + 120;
for (int i = 0; i < plotNum; i++) {
float iRatio = map(i, 0, plotNum, 0.0, 1.0);
float fX = width * iRatio;
float fY = height * (0.5 + 0.4 * waveCalc(iRatio, radians));
// translate wave shape into polar coordinates
float x = fY * cos(fX) * 0.5;
float y = fY * sin(fX) * 0.5;
vertex(x, y);
}
vertex(0.0, 0.0);
endShape(CLOSE);
// draw casing
casing();
}
/**
* waveCalc calculate the wave shape.
* @param _ratio : any value.
* @param _rad : any value.
* @return float -1.0 - 1.0 : calculated value.
*/
public float waveCalc(float _ratio, float _rad) {
return cos(_ratio * _rad) * sin(_ratio + _rad * 0.5);
}
/**
* resetPtn reset pattern parameters (global variables).
*/
public void resetPtn() {
initPlot += 39; //
initPlot %= 100;
initHue += 90.0;
initRad = random(-TWO_PI, TWO_PI) * 2.0;
}
/**
* casing : draw fancy casing
*/
public void casing() {
fill(0.0, 0.0, 0.0, 0.0);
strokeWeight(26.0);
stroke(0.0, 0.0, 0.0, 100.0);
rect(0.0, 0.0, width, height);
strokeWeight(20.0);
stroke(0.0, 0.0, 100.0, 100.0);
rect(0.0, 0.0, width, height);
}
/**
* easeInOutCosine easing function.
* @param _t 0.0 - 1.0 : linear value.
* @return float 0.0 - 1.0 : eased value.
*/
public float easeInOutCosine(float _t) {
return 0.5 - cos(PI * _t) * 0.5;
}
/*
Copyright (C) 2020- deconbatch
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>
*/
```

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